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Captopril or prostaglandin E1 ameliorate adverse renal hemodynamic effects of indomethacin in uninephrectomized rats
TOXICOLOGY
AND
APPLIED
PHARMACOLOGY
98,3 1-38 (1989)
Captopril or Prostaglandin El Ameliorate Adverse Renal Hemodynamic Effects of lndomethacin in Uninephrectomized Rats MARTINJ.FETTMANAND Comparative
Nephrology Colorado
Received
W. LEE WILKE
Unit, College of Veterinary Medicine and Biomedical State University, Fort Collins, Colorado 80523
June 6, 1988; accepted
November
Sciences,
14, 1988
Captopril or Prostaglandin E, Ameliorate Adverse Renal Hemodynamic Effects of Indomethacin in Uninephrectomized Rats. FETTMAN, M. J. AND WILKE, W. L. (1989). Toxicol. Appl. Pharmacol. 98,3 l-38. Nonsteroidal anti-inflammatory drugs like indomethacin and angiotensin converting enzyme inhibitors like captopril have contrasting effects on compensatory changes in glomerular filtration rate and renal blood flow following partial nephrectomy. Conjoint treatment has been little studied. Effects of 7 days of treatment with captopril, indomethatin, or captopril + indomethacin in drinking water were studied in 50% nephrectomized Sprague-Dawley rats. Urinary protein excretion, glomerular filtration rate, effective renal plasma flow (ERPF), mean arterial pressure, renal vascular resistance, and remnant kidney weight were measured. Renal clearance studies were performed using a double-isotope, singleinjection method, in conscious rats infused with either saline or saline + prostaglandin E, . Indomethacin induced significant (p < 0.05) increases in renal vascular resistance (RVR) which were attenuated by either concurrent treatment with captopril or infusion of PGE, at the time of study. Compensatory growth of the remnant kidney appeared not to be dependent on increments in renal blood flow; captopril decreased RVR and increased ERPF but had no effect on kidney weight, while indomethacin had no effect on ERPF and augmented remnant kidney weight. It appears effects of captopril and indomethacin on intrarenal hemodynamics in the residual kidney were counteractive, and that conjoint therapy in renal disease should be ag proached with caution. o 1989 Academic PKSS, IX.
Renal blood flow and glomerular ultrafiltration are significantly influenced by alterations in both locally produced and systemic vasoactive humors. Drugs which influence the release or action of these humoral factors may be beneficial while modifying compensatory mechanisms in the remnant kidney following partial nephrectomy or other injury (Hall et al., 1985, 1986a, 1986b; Radin et al., 1986a, 1987). Angiotensin II affects renal blood flow and glomerular filtration rate through its vasoconstrictive effects, predominantly on the efferent arteriole, and through its contractile effects on the mesangial cells, thereby reducing ultrafiltration coefficient (Blantz and Pel-
ayo, 1983; Navar and Rosiwall, 1984; Kastner et al., 1984). Through the inhibition of angiotensin-converting enzyme and kininase activities, drugs like captopril may promote renal blood flow and glomerular ultrafiltration in normal and remnant kidneys (Clappison et al., 198 1; Hall et al., 1985). In addition, through concurrent reductions in intraglomerular hypertension associated with compensatory nephron hypertrophy, these drugs may reduce proteinuria and retard progressive glomerular deterioration in remnant kidney models (Hall et al., 1985; Beukers et al., 1987; Heeg et al., 1987). Vasodilatory and vasoconstrictive prostanoids regulate renal blood flow and glomeru31
0041-008X/89
$3.00
Copyright 0 1989 by Academic Press. Inc. All rights of reproduction m any form resew&
32
FETTMAN
lar ultrafiltration through their effects on preand postglomerular arterioles and glomerulotubular balance (Chrysant, 1978; Jackson et al., 1982; Yoshida et al., 1986). The latter is influenced by effects on renal tubular solute absorption and distal nephron water kinetics (Chrysant, 1978). In the normal kidney, nonsteroidal anti-inflammatory drugs like indomethacin may reduce renal blood flow, osmolal clearance, and free water clearance, with or without effects on glomerular filtration rate (Chrysant, 1978). In remnant kidneys, these effects are extended to significant reductions in glomerular ultrafiltration as well (Dunn and Zabraski, 1980; Stahl et al., 1986). Replacement of vasodilators (PGE, , PGE*, or PGI*) or selective inhibition of thromboxane synthesis may reverse these effects (Jackson et al., 1982; Stahl et al., 1986). Systemic administration of vasodilatory prostanoids at doses having no effect on mean arterial blood pressure may significantly reduce renal vascular resistance in normal kidneys (Yoshida et al., 1986). While the mechanisms of action of many vasoactive drugs have been well studied following solitary administration, data regarding effects of conjoint administration on remnant nephron function are limited. This is of particular clinical relevance in those individuals with compromised renal function who, by necessity, must receive nonsteroidal antiinflammatory drug therapy. One may hypothesize that concurrent treatment with an angiotensin-converting enzyme inhibitor or substitute vasodilatory prostaglandin therapy may alleviate potential untoward effects. In addition, the effects of experimental single and conjoint drug regimens may be confounded by anesthetic methods required for quantitative clearance studies to be performed (Walker et al., 1986). Specifically, captopril was shown to prevent reductions in glomerular filtration rate and effective renal plasma flow otherwise induced by pentobarbital anesthesia in rats (Walker et al., 1986). The objectives of this study were to document the effects, if any, of indomethacin, cap-
AND WILKE
topril, PGEi , or a combination of the former two, on renal hemodynamics in an acute, “subclinical” model of reduced renal function, unencumbered by the potential confounding effects of anesthesia.
METHODS Experiments were performed on male Sprague-Dawley rats (Charles River Breeding Laboratories, Wilmington, MA), weighing 350-400 g at the time of surgery. Commercial rat chow (Ralston Purina Co., St. Louis, MO) and drinking water were given ad libitum throughout the experiments. All rats were housed in pairs in an environment with a 12-hr photoperiod and 2 1°C temperature control. Right uninephrectomy (Day 0) and catheterization (Day 5) surgeries were performed under general anesthesia using intramuscular ketamine (67 mp/kg) and xylazine (6.7 mg/kg). The aorta was catheterized via the left external carotid artery with PESO polyethylene material. Catheters were filled with heparinized saline, sealed, coiled, and sutured to the dorsal cervical region. Effects of 7 days of treatment with captopril(60 mg/ kg/day) (E. R. Squibb and Sons, Inc., Princeton, NJ), indomethacin (4.7 mg/kg/day) (Sigma Chemical Co., St. Louis, MO), or captopril + indomethacin in drinking water were studied in 14 control and 44 50% nephrectomized rats. After 5 days, rats were placed in metabolic cages for quantitative, timed urine collections. Urinary protein (mg/24 hr) was measured using the Coomassie brilliant blue dye binding method (Bio-Rad Laboratories, Richmond, CA). Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured in conscious rats, using a single-injection, double-isotope method. The former was quantitated through the clearance of ‘H-inulin (New England Nuclear, MA), and latter through the clearance of “C-tetraethylammonium bromide (TEA) (New England Nuclear, MA) as we have previously described (Radin et al., 1986b). During the clearance study, rats were either infused with sterile isotonic saline to replace sampled blood volume or infused with saline containing ( 11ol, 13E, 15S)- 11,15-dihydroxy-9-oxoprost- 13en- 1-oic acid (PGE,) (Aloprostadil; The Upjohn Co., Kalamazoo, MI) to deliver 200 ng/kg/min. This dose has previously been shown to have no effect on systemic blood pressure, while significantly altering renal hemodynamics (Jackson et al., 1982; Yoshida et al., 1986). Mean arterial blood pressure (MAP) was measured before and after the clearance studies in these conscious rats using a transducer (Statham Instruments, Inc.) attached to the carotid arterial catheter. At the end of each study, the rats were euthanatized with an intraarterial overdose
INDOMETHACIN
AND CAPTOPRIL TABLE
33
ON NEPHRECTOMY
1
EFFECTSOF 50% NEPHRECTOMY, CAPTOPRIL, INDOMETHACIN, AND/OR PROSTAGLANDIN E, ON 24-hr URINARY PROTEIN EXCRETION AND MEAN ARTERIAL BLOOD PRESSUREIN RATS
Treatment
n
Control Uninephrectomy (Nx) Nx + captopril Nx + indomethacin Nx + captopril + indomethacin Control + PGE, Nx + PGE, Nx + indomethacin + PGE,
7 8 8 7 7 7 7 7
24-hr Urinary protein excretion (w) 222 34+ 38k 22k 27k 22k 4Ok 36rt
3 12 18 10 11 4 16 18
Mean arterial pressure (mm J&l 94+23 87r21 76 + 15* 97 ‘- 25 89k 19 99 + 22 101 + 24 89k 17
* p < 0.05 compared to control group.
of sodium pentobarbital. Kidneys and heart were removed and weighed. Differences between all treatment groups in 24-hr water intake, urine output, and urinary protein excretion, and GFR, ERPF, filtration fraction (FF), MAP, left ventricle/interventricular septal weight, and remnant kidney weight were evaluated by analysis of variance (Steel and Torrie, 1980). Means were ranked using Fisher’s least significant difference test to determine differences among all groups, including intact, nephrectomized, and drugtreated animals (Steel and Torrie, 1980). Differences in remnant kidney weight for pooled dam between all indomethacin and non-indomethacin-treated rats were evaluated by unpaired t test (Steel and Torrie, 1980). Data are reported as means f standard deviation.
RESULTS In this short-term study, body weight and water intake were not affected by treatment. After 5 days, urinary protein excretion (mg/ 24 hr) was numerically increased in all nephrectomized rats, with no significant differences between any of the groups. After 7 days, GFR (3H-inulin), ERPF (14C-TEA), and arterial pressure were measured in conscious rats infused with saline or PGE, . MAP (mm Hg) was unaffected by nephrectomy, with or without indomethacin, and with or without PGE, , or in nephrectomized rats treated with indomethacin and captopril (Table 1). MAP was reduced in nephrectomized rats treated
with captopril alone (76 * 15) vs control (94 f 23) (Table 1). GFR and ERPF per kilogram body weight (ml/min/kg) were reduced by nephrectomy (4.86 + 1.19 and 22.04 & 4.65) compared to controls (7.22 rt 1.84 and 30.02 + 6.92), but unaffected by treatment (Fig. 1). ERPF per gram kidney weight (ml/min/g) was unaffected by nephrectomy with or without indomethacin, and with or without PGE, , vs control (3.82 f 0.49) (Fig. 2). ERPF per gram kidney weight was increased in nephrectomized rats receiving captopril (4.79 f 0.90) compared to that in controls and to that in indomethacin-treated nephrectomized rats (3.84 + 0.89) (Fig. 2). Filtration fraction (%) in nephrectomized rats (0.22 + 0.07) was not affected by captopril (0.21 + 0.04) but was increased by indomethacin (0.27 f 0.06). Renal vascular resistance (RVR) (MAP/ERPF per gram kidney weight; mm Hg (ml/min/g)-‘)) was reduced in captop&-treated nephrectomized rats ( 15.96) vs controls (25.33) (Fig. 3). RVR in indomethatin-treated nephrectomized rats (26.83) was higher than that in untreated nephrectomized rats ( 19.13) (Fig. 3). Nephrectomized rats receiving both captopril and indomethatin had renal vascular resistance values intermediate to the above groups (19.79) and similar to the untreated nephrectomized rats
34
FETTMAN
control
50%
Nx
Nx+cap
AND WILKE
Nx+lnd
Nx+cap +Ind
conlrol +PG
Nx+PG
Nx+ind +PG
Treatment FIG. 1. Effects of 50% nephrectomy, captopril, indomethacin, and/or prostaglandin E, on effective renal plasma flow (ERPF) (Cm,) and glomerular filtration rate (C+,&, expressed per kilogram body weight, in rats. All nephrectomy groups experienced a significant (p i 0.05) decrease in ERPF compared to control groups (*). Control, sham opetated, 50% Nx, uninephrectomy; cap, captropril; ind, indomethacin; PG, effective renal plasma flow; I, glomerular filtration area.
(Fig. 3). Residual kidney weight was greater in nephrectomized rats given indomethacin, and in nephrectomized rats given indomethacin with captopril, than that in untreated nephrectomized rats (5.39 f 0.65 and 5.50 +- 0.8 1 vs 4.85 + 0.48 g, respectively), but was not affected by captopril alone (Fig. 4). DISCUSSION It appears that effects of indomethacin on intrarenal vascular resistance in the residual kidney were counteracted by captopril. There was apparently a trend toward decreased renal vascular resistance in untreated nephrectomized rats compared to controls, as reported in young, uninephrectomized rats (Chevalier and Kaiser, 1985; Chevalier et al., 1987) and in adult rats with nephrotoxic serum nephritis (Kaizu et al., 1985). Captopril
reduced renal vascular resistance in nephrectomized rats significantly (p < 0.05), compared to control rats; ERPF per gram kidney weight was increased (p < 0.05) and mean arterial pressure was decreased (p < 0.05). This effect has been observed in young uninephrectomized rats treated with another angiotensin-converting enzyme inhibitor (Chevalier et al., 1987) and in rats with nephrotoxic serum nephritis (Kaizu et al., 1985). Indomethacin alone increased renal vascular resistance in nephrectomized rats, as was reported for nephrotoxic serum nephritis (Kaizu et al., 1985). In young, uninephrectomized rats, RVR at normal systemic blood pressure was unaffected following acute treatment with indomethacin and meclofenamate, but decreased at lower renal perfusion pressures (Chevalier et al., 1987). This effect was attributed to reductions in prostaglandin-stimulated renin release and subsequent
INDGMETHACIN
AND CAPTOPRIL
ON NEPHRECTOMY
-I Control
50%
Nx
-I Nx+cap
Nx+ind
Nx+cap +ind
control +PG
Nx+PG
Nx+ind +PG
Treatment FIG. 2. Effects of 50% nephrectomy, captopril, indomethacin, and/or prostaglandin E, on effective renal plasma flow (ERPF) (CT& and glomerular filtration rate (Cinulln) , expressed per gram kidney weight, in rats. Captopril-treated nephrectomized rats experienced a significant (p < 0.05) increase (*) in ERPF compared to the control group. Control, sham operated; 50% Nx, uninephrectomy; cap, captopril: ind. indomethacin; PG, prostaglandin E, ; effective renal plasma flow: I, glomerular filtration rate.
+ ContrOt
50%
Nx NX+Cap
Nx+ind
Nx+cap +Ind
control Nx+PG +PG
4 NX+lnd +PG
Treatment
FIG. 3. Effects of 50% nephrectomy, captopril, indomethacin, and/or prostaglandin E, on renal vascular resistance (RVR) in rats. Captopril-treated nephrectomized rats experienced a significant (p < 0.05) decrease (*) in RVR compared to the control group. Indomethacin-treated nephrectomized rats experienced a significant (p < 0.05) increase (t) in RVR compared to the uninephrectomy group. Control. sham operated: 50% Nx, uninephrectomy: cap, captopril; ind, indomethacin; PC, prostaglandin E,
36
FETTMAN
AND WILKE
z
6.0
z m
6.0
3
5.0
z
6.0
4.0
p” :: i0
4.0
CD
6 2 Ya 9 E m %
3.0
9 E
3.0
2.0
_a D
2.0
ff
1 .o
f
1 .o
B
s
0.0
0.0 NX and
Nx+lnd and
Nx+PG
Nx+ind+PG
Nx+cap+ind
Nx+cap Treatment
Treatment
FIG. 4. Effects of captopril and/or indomethacin on remnant kidney weight in 50% nephrectomized rats. Data from rats receiving PGE, infusion are pooled with those who did not, as this would not have affected residual renal hypertrophy. Nx, uninephrectomy; ind, indomethacin; cap, captopril; PG, prostaglandin El.
angiotensin II activation, following cyclooxygenase inhibition (Chevalier et al., 1987). In the present study of adult rats at normal systemic blood pressure, indomethacin-induced increases in RVR were muted by acute infusion of prostaglandin El. This occurred despite the inevitable stimulation of renin release by the infused prostaglandin (Suzuki et al., 198 1). Indomethacin’s effect on RVR was attenuated by conjoint treatment with captopril. In anesthetized, sodium-restricted dogs, indomethacin increased RVR and systemic arterial blood pressure and decreased ERPF and GFR (Carmines et al., 198 3). Subsequent captopril treatment was shown to decrease RVR and systemic blood pressure and to increase ERPF and GFR, suggesting the renal response to captopril is not mediated by alterations in prostaglandin synthesis, but due to reductions in angiotensin II (Carmines et al., 1983). Likewise, in conscious dogs pretreated with indomethacin, ERPF, GFR, urinary sodium excretion, and plasma renin activity were increased following conjoint captopril administration (DeForrest et al., 1982). Together with the present study, these findings support concurrent and opposite roles for angiotensin II and vasodilatory prostanoids in the control of remnant kidney vascular resis-
tance in unanesthetized, 50% nephrectomized rats. Alterations in FF concur with this interpretation; indomethacin increased FF, while captopril counteracted this effect. Indomethacin enhanced compensatory renal growth, but despite increased ERPF, captopril had no such effect. Thus, in this shortterm model, renal compensatory growth appeared not to be dependent on renal vasodilation or increments in blood flow. The clinical relevance of this observation is speculative. Absence of other significant effects of indomethacin or PGE, in normal and nephrectomized rats in this study conflicts in part with previous findings in anesthetized animals following removal of larger amounts of kidney and studied for a longer period of time. This may be attributed to confounding effects of anesthesia in other studies, where reduced arterial pressure, increased renal vascular resistance, and increased renal prostanoid release have been documented (Walker et al., 1986), and/or to insufficient dosage of drugs in the present study. In the nephrectomized rats, minimal drug effects may additionally have been due to the minimal remnant nephron damage following only 50% nephrectomy and/or 7 days of compensatory changes. Subtle physiological changes ob-
INDOMETHACIN
AND CAPTOPRIL
served in this study may chronically accentuate or advance renal dysfunction. Adverse effects of indomethacin in rats with minimal renal compromise demonstrate the propensity for exacerbation of subclinical renal disease in human beings receiving nonsteroidal anti-inflammatory drugs. One may speculate that longer term treatment would elicit more overt signs of renal dysfunction. Likewise, the apparent ameliorative effects of concurrent captopril treatment might delay those effects over a longer period of time, but this should be studied further. Additional studies should address the potential problems identified above, particularly effects of anesthesia on clearance functions and greater remnant nephron damage following 75% nephrectomy and/or longer periods of compensation. Concurrent therapy with angiotensin-converting enzyme inhibitors and nonsteroidal anti-inflammatory drugs should be approached with caution in renal disease, owing to inhibition of beneficial effects of the former by the latter. Conversely, and most importantly, angiotensinconverting enzyme inhibitors may moderate adverse renal effects of nonsteroidal anti-inflammatory drugs administered by necessity to patients with renal disease. ACKNOWLEDGMENTS The investigators express appreciation to E. R. Squibb and Sons, Inc., for the donation of captopril and to the Upjohn Co. for the donation of Prostin VR (alprostadil) for use in these studies.
REFERENCES BEUKERS, J. J. B., VAN DER WAL, A., HOEDEMAEKER, P. J., AND WEENING, J. J. (1987). Converting enzyme inhibition and progressive glomerulosclerosis in the rat. Kidney Int. 32,794-800. BLANTZ, R., AND PELAYO, J. C. (1983). In vivo actions of angiotensin II on glomerular function. Fed. Proc. 42,307 l-3074. CARMINES, P. K., ROSIVALL, L., TILL, M. F., AND NAVAR, L. G. (1983). Renal hemodynamic effects of captopril in anesthetized sodium-restricted dogs. Relative
ON NEPHRECTOMY
37
contributions of prostaglandin stimulation and suppressed angiotensin activity. Renal Physiol. 6, 281287. CHEVALIER. R. L., CAREY, R. M., AND KAISER, D. L. ( 1987). Endogenous prostaglandins modulate autoregulation of renal blood flow in young rats. Amer. J. Physiol. 253, F66-F75. CHEVALIER, R. L., AND KAISER, D. L. (1985). Effects of acute uninephrectomy and age on renal blood flow autoregulation in the rat. Amer. J. Physiol. 249, F672F679. CHRYSANT, S. G. (1978). Renal functional changes induced by prostaglandin E 1 and indomethacin on the anesthetized dog. Arch. Int. Pharmacodyn. Ther. 234, 156-163. CLAPPISON, B. H., ANDERSON, W. P., AND JOHNSTON, C. I. (198 I). Renal hemodynamics and renal kinins after angiotensin converting enzyme inhibition. Kidney Int. 20,6 15-620. DEFORREST, J. M., WALDRON, T. L.. AND ANTONACCIO, M. J. (1982). Renal response to captopril in conscious dogs pretreated with indomethacin. Amer J Physiol.
243, G543-G548.
DUNN, M. J., AND ZABRASKI, E. J. (1980). Renal effects of drugs that inhibit prostaglandin synthesis. Kidney Int. l&609-622.
HALL, R. L., WILKE, W. L., AND FETTMAN, M. J. (1985). Captopril slows the progression of chronic renal disease in partially nephrectomized rats. Toxicol. .4ppl. Pharmacol. 80,5 17-526. HALL, R. L., WILKE, W. L., AND FETTMAN, M. J. ( 1986a). The progression of adriamycin-induced nephrotic syndrome in rats and the effect of captopril. Toxicol. Appl. Pharmacol. 82, 164- 174. HALL, R. L., WILKE, W. L., AND FETTMAN, M. J. (1986b). Effect of captopril on the progression of experimentally-induced pyelonephritis in the rat. Amer. J. Vet. Res. 47, 1085-1088.
HEEG, J. E.. DE JONG, P. E., VAN DER HEM, G. K., AND DE ZEEUW, D. (1987). Reduction of proteinuria by angiotensin converting enzyme inhibition. Kidney Int. 32,78-83. JACKSON, E. K., HEIDEMANN. H. T., BRANCH, R. A., AND GERKENS, J. F. (1982). Low dose intrarenal infusions of PGEZ, PGI2, and 6-keto-PGEI vasodilate the in vivo rat kidney. Circ. Res. S&67-72. KAIZU. K., MARSH, D.. ZIPSER, R., AND GLASSOCK, R. J. (1985). Role of prostanoids and angiotensin II in experimental glomerulonephritis. Kidney Int. 28. 629-635. KASTNER, P. R., HALL, J. E., AND GUYTON, A. C. (1984). Control of glomerular filtration rate: Role of intrarenally formed angiotensin II. Amer. J. Physiol. 246, F897-F906. NAVAR, I. G., AND ROSIWALL, L. ( 1984). Contribution of the renin-angiotensin system to the control of intrarenal hemodynamics. Kidney Int. 25,857-868.
38
FETTMAN
RADIN, M. J., WILKE, W. L., AND FETTMAN, M. J. (1986a). Effects of captopril on chronic puromycin aminonucleoside nephrosis in rats. Rex Commun. Chem. Pathol. Pharmacol. 54,219-282. RADIN, M. J., FETTMAN, M. J., AND WILKE, W. L. (1986b). Single injection method for evaluation of renal function with 3H-inulin and ‘%-tetraethylammonium bromide in conscious, unrestrained SpragueDawley rats. J. Amer. Vet. Med. Assoc. 189, 10441046. RADIN, M. J., WILKE, W. L., AND FETTMAN, M. J. (I 987). Effect ofpropranolol on progression of chronic renal disease in partially nephrectomized rats. Res. Commun. Chem. Pathol. Pharmacol. 57,3- 13. STAHL, R. A. K., KUDELKA, S., PARAVICINI, M., AND SCHOLLMEYER, P. (1986). Prostaglandin and throm-
AND WILKE boxane formation in glomeruli form rats with reduced renal mass. Nephron 42,252-257. STEEL, R. G. D., AND TORRIE, J. H. ( 1980). In Principles and Procedures of Statistics, 2nd ed. McGraw-Hill, New York. SUZUKI, S., FRANCO-SAENZ, R., TAN, S. Y., AND MUL ROW, P. J. (198 1). Effects of indomethacin on plasma renin activity in the conscious rat. Amer. J. Physiol. 240, E286-E289. WALKER, L. A., GELLAI, M., AND VALTIN, H. (1986). Renal response to pentobarbital anesthesia in rats: Effect of interrupting the renin-angiotensin system. J. Pharmacol. Exp. Ther. 236,72 l-728. YOSHIDA, M., UEDA, S., SOEJIMA, H., TSURUTA, K., AND IREGAMI, K. ( 1986). Effects of prostaglandin E2 and I2 on renal cortical and medulhuy blood flow in rabbits. Arch. Int. Pharmacodyn. Ther. 282,108-l 1I.
AND
APPLIED
PHARMACOLOGY
98,3 1-38 (1989)
Captopril or Prostaglandin El Ameliorate Adverse Renal Hemodynamic Effects of lndomethacin in Uninephrectomized Rats MARTINJ.FETTMANAND Comparative
Nephrology Colorado
Received
W. LEE WILKE
Unit, College of Veterinary Medicine and Biomedical State University, Fort Collins, Colorado 80523
June 6, 1988; accepted
November
Sciences,
14, 1988
Captopril or Prostaglandin E, Ameliorate Adverse Renal Hemodynamic Effects of Indomethacin in Uninephrectomized Rats. FETTMAN, M. J. AND WILKE, W. L. (1989). Toxicol. Appl. Pharmacol. 98,3 l-38. Nonsteroidal anti-inflammatory drugs like indomethacin and angiotensin converting enzyme inhibitors like captopril have contrasting effects on compensatory changes in glomerular filtration rate and renal blood flow following partial nephrectomy. Conjoint treatment has been little studied. Effects of 7 days of treatment with captopril, indomethatin, or captopril + indomethacin in drinking water were studied in 50% nephrectomized Sprague-Dawley rats. Urinary protein excretion, glomerular filtration rate, effective renal plasma flow (ERPF), mean arterial pressure, renal vascular resistance, and remnant kidney weight were measured. Renal clearance studies were performed using a double-isotope, singleinjection method, in conscious rats infused with either saline or saline + prostaglandin E, . Indomethacin induced significant (p < 0.05) increases in renal vascular resistance (RVR) which were attenuated by either concurrent treatment with captopril or infusion of PGE, at the time of study. Compensatory growth of the remnant kidney appeared not to be dependent on increments in renal blood flow; captopril decreased RVR and increased ERPF but had no effect on kidney weight, while indomethacin had no effect on ERPF and augmented remnant kidney weight. It appears effects of captopril and indomethacin on intrarenal hemodynamics in the residual kidney were counteractive, and that conjoint therapy in renal disease should be ag proached with caution. o 1989 Academic PKSS, IX.
Renal blood flow and glomerular ultrafiltration are significantly influenced by alterations in both locally produced and systemic vasoactive humors. Drugs which influence the release or action of these humoral factors may be beneficial while modifying compensatory mechanisms in the remnant kidney following partial nephrectomy or other injury (Hall et al., 1985, 1986a, 1986b; Radin et al., 1986a, 1987). Angiotensin II affects renal blood flow and glomerular filtration rate through its vasoconstrictive effects, predominantly on the efferent arteriole, and through its contractile effects on the mesangial cells, thereby reducing ultrafiltration coefficient (Blantz and Pel-
ayo, 1983; Navar and Rosiwall, 1984; Kastner et al., 1984). Through the inhibition of angiotensin-converting enzyme and kininase activities, drugs like captopril may promote renal blood flow and glomerular ultrafiltration in normal and remnant kidneys (Clappison et al., 198 1; Hall et al., 1985). In addition, through concurrent reductions in intraglomerular hypertension associated with compensatory nephron hypertrophy, these drugs may reduce proteinuria and retard progressive glomerular deterioration in remnant kidney models (Hall et al., 1985; Beukers et al., 1987; Heeg et al., 1987). Vasodilatory and vasoconstrictive prostanoids regulate renal blood flow and glomeru31
0041-008X/89
$3.00
Copyright 0 1989 by Academic Press. Inc. All rights of reproduction m any form resew&
32
FETTMAN
lar ultrafiltration through their effects on preand postglomerular arterioles and glomerulotubular balance (Chrysant, 1978; Jackson et al., 1982; Yoshida et al., 1986). The latter is influenced by effects on renal tubular solute absorption and distal nephron water kinetics (Chrysant, 1978). In the normal kidney, nonsteroidal anti-inflammatory drugs like indomethacin may reduce renal blood flow, osmolal clearance, and free water clearance, with or without effects on glomerular filtration rate (Chrysant, 1978). In remnant kidneys, these effects are extended to significant reductions in glomerular ultrafiltration as well (Dunn and Zabraski, 1980; Stahl et al., 1986). Replacement of vasodilators (PGE, , PGE*, or PGI*) or selective inhibition of thromboxane synthesis may reverse these effects (Jackson et al., 1982; Stahl et al., 1986). Systemic administration of vasodilatory prostanoids at doses having no effect on mean arterial blood pressure may significantly reduce renal vascular resistance in normal kidneys (Yoshida et al., 1986). While the mechanisms of action of many vasoactive drugs have been well studied following solitary administration, data regarding effects of conjoint administration on remnant nephron function are limited. This is of particular clinical relevance in those individuals with compromised renal function who, by necessity, must receive nonsteroidal antiinflammatory drug therapy. One may hypothesize that concurrent treatment with an angiotensin-converting enzyme inhibitor or substitute vasodilatory prostaglandin therapy may alleviate potential untoward effects. In addition, the effects of experimental single and conjoint drug regimens may be confounded by anesthetic methods required for quantitative clearance studies to be performed (Walker et al., 1986). Specifically, captopril was shown to prevent reductions in glomerular filtration rate and effective renal plasma flow otherwise induced by pentobarbital anesthesia in rats (Walker et al., 1986). The objectives of this study were to document the effects, if any, of indomethacin, cap-
AND WILKE
topril, PGEi , or a combination of the former two, on renal hemodynamics in an acute, “subclinical” model of reduced renal function, unencumbered by the potential confounding effects of anesthesia.
METHODS Experiments were performed on male Sprague-Dawley rats (Charles River Breeding Laboratories, Wilmington, MA), weighing 350-400 g at the time of surgery. Commercial rat chow (Ralston Purina Co., St. Louis, MO) and drinking water were given ad libitum throughout the experiments. All rats were housed in pairs in an environment with a 12-hr photoperiod and 2 1°C temperature control. Right uninephrectomy (Day 0) and catheterization (Day 5) surgeries were performed under general anesthesia using intramuscular ketamine (67 mp/kg) and xylazine (6.7 mg/kg). The aorta was catheterized via the left external carotid artery with PESO polyethylene material. Catheters were filled with heparinized saline, sealed, coiled, and sutured to the dorsal cervical region. Effects of 7 days of treatment with captopril(60 mg/ kg/day) (E. R. Squibb and Sons, Inc., Princeton, NJ), indomethacin (4.7 mg/kg/day) (Sigma Chemical Co., St. Louis, MO), or captopril + indomethacin in drinking water were studied in 14 control and 44 50% nephrectomized rats. After 5 days, rats were placed in metabolic cages for quantitative, timed urine collections. Urinary protein (mg/24 hr) was measured using the Coomassie brilliant blue dye binding method (Bio-Rad Laboratories, Richmond, CA). Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured in conscious rats, using a single-injection, double-isotope method. The former was quantitated through the clearance of ‘H-inulin (New England Nuclear, MA), and latter through the clearance of “C-tetraethylammonium bromide (TEA) (New England Nuclear, MA) as we have previously described (Radin et al., 1986b). During the clearance study, rats were either infused with sterile isotonic saline to replace sampled blood volume or infused with saline containing ( 11ol, 13E, 15S)- 11,15-dihydroxy-9-oxoprost- 13en- 1-oic acid (PGE,) (Aloprostadil; The Upjohn Co., Kalamazoo, MI) to deliver 200 ng/kg/min. This dose has previously been shown to have no effect on systemic blood pressure, while significantly altering renal hemodynamics (Jackson et al., 1982; Yoshida et al., 1986). Mean arterial blood pressure (MAP) was measured before and after the clearance studies in these conscious rats using a transducer (Statham Instruments, Inc.) attached to the carotid arterial catheter. At the end of each study, the rats were euthanatized with an intraarterial overdose
INDOMETHACIN
AND CAPTOPRIL TABLE
33
ON NEPHRECTOMY
1
EFFECTSOF 50% NEPHRECTOMY, CAPTOPRIL, INDOMETHACIN, AND/OR PROSTAGLANDIN E, ON 24-hr URINARY PROTEIN EXCRETION AND MEAN ARTERIAL BLOOD PRESSUREIN RATS
Treatment
n
Control Uninephrectomy (Nx) Nx + captopril Nx + indomethacin Nx + captopril + indomethacin Control + PGE, Nx + PGE, Nx + indomethacin + PGE,
7 8 8 7 7 7 7 7
24-hr Urinary protein excretion (w) 222 34+ 38k 22k 27k 22k 4Ok 36rt
3 12 18 10 11 4 16 18
Mean arterial pressure (mm J&l 94+23 87r21 76 + 15* 97 ‘- 25 89k 19 99 + 22 101 + 24 89k 17
* p < 0.05 compared to control group.
of sodium pentobarbital. Kidneys and heart were removed and weighed. Differences between all treatment groups in 24-hr water intake, urine output, and urinary protein excretion, and GFR, ERPF, filtration fraction (FF), MAP, left ventricle/interventricular septal weight, and remnant kidney weight were evaluated by analysis of variance (Steel and Torrie, 1980). Means were ranked using Fisher’s least significant difference test to determine differences among all groups, including intact, nephrectomized, and drugtreated animals (Steel and Torrie, 1980). Differences in remnant kidney weight for pooled dam between all indomethacin and non-indomethacin-treated rats were evaluated by unpaired t test (Steel and Torrie, 1980). Data are reported as means f standard deviation.
RESULTS In this short-term study, body weight and water intake were not affected by treatment. After 5 days, urinary protein excretion (mg/ 24 hr) was numerically increased in all nephrectomized rats, with no significant differences between any of the groups. After 7 days, GFR (3H-inulin), ERPF (14C-TEA), and arterial pressure were measured in conscious rats infused with saline or PGE, . MAP (mm Hg) was unaffected by nephrectomy, with or without indomethacin, and with or without PGE, , or in nephrectomized rats treated with indomethacin and captopril (Table 1). MAP was reduced in nephrectomized rats treated
with captopril alone (76 * 15) vs control (94 f 23) (Table 1). GFR and ERPF per kilogram body weight (ml/min/kg) were reduced by nephrectomy (4.86 + 1.19 and 22.04 & 4.65) compared to controls (7.22 rt 1.84 and 30.02 + 6.92), but unaffected by treatment (Fig. 1). ERPF per gram kidney weight (ml/min/g) was unaffected by nephrectomy with or without indomethacin, and with or without PGE, , vs control (3.82 f 0.49) (Fig. 2). ERPF per gram kidney weight was increased in nephrectomized rats receiving captopril (4.79 f 0.90) compared to that in controls and to that in indomethacin-treated nephrectomized rats (3.84 + 0.89) (Fig. 2). Filtration fraction (%) in nephrectomized rats (0.22 + 0.07) was not affected by captopril (0.21 + 0.04) but was increased by indomethacin (0.27 f 0.06). Renal vascular resistance (RVR) (MAP/ERPF per gram kidney weight; mm Hg (ml/min/g)-‘)) was reduced in captop&-treated nephrectomized rats ( 15.96) vs controls (25.33) (Fig. 3). RVR in indomethatin-treated nephrectomized rats (26.83) was higher than that in untreated nephrectomized rats ( 19.13) (Fig. 3). Nephrectomized rats receiving both captopril and indomethatin had renal vascular resistance values intermediate to the above groups (19.79) and similar to the untreated nephrectomized rats
34
FETTMAN
control
50%
Nx
Nx+cap
AND WILKE
Nx+lnd
Nx+cap +Ind
conlrol +PG
Nx+PG
Nx+ind +PG
Treatment FIG. 1. Effects of 50% nephrectomy, captopril, indomethacin, and/or prostaglandin E, on effective renal plasma flow (ERPF) (Cm,) and glomerular filtration rate (C+,&, expressed per kilogram body weight, in rats. All nephrectomy groups experienced a significant (p i 0.05) decrease in ERPF compared to control groups (*). Control, sham opetated, 50% Nx, uninephrectomy; cap, captropril; ind, indomethacin; PG, effective renal plasma flow; I, glomerular filtration area.
(Fig. 3). Residual kidney weight was greater in nephrectomized rats given indomethacin, and in nephrectomized rats given indomethacin with captopril, than that in untreated nephrectomized rats (5.39 f 0.65 and 5.50 +- 0.8 1 vs 4.85 + 0.48 g, respectively), but was not affected by captopril alone (Fig. 4). DISCUSSION It appears that effects of indomethacin on intrarenal vascular resistance in the residual kidney were counteracted by captopril. There was apparently a trend toward decreased renal vascular resistance in untreated nephrectomized rats compared to controls, as reported in young, uninephrectomized rats (Chevalier and Kaiser, 1985; Chevalier et al., 1987) and in adult rats with nephrotoxic serum nephritis (Kaizu et al., 1985). Captopril
reduced renal vascular resistance in nephrectomized rats significantly (p < 0.05), compared to control rats; ERPF per gram kidney weight was increased (p < 0.05) and mean arterial pressure was decreased (p < 0.05). This effect has been observed in young uninephrectomized rats treated with another angiotensin-converting enzyme inhibitor (Chevalier et al., 1987) and in rats with nephrotoxic serum nephritis (Kaizu et al., 1985). Indomethacin alone increased renal vascular resistance in nephrectomized rats, as was reported for nephrotoxic serum nephritis (Kaizu et al., 1985). In young, uninephrectomized rats, RVR at normal systemic blood pressure was unaffected following acute treatment with indomethacin and meclofenamate, but decreased at lower renal perfusion pressures (Chevalier et al., 1987). This effect was attributed to reductions in prostaglandin-stimulated renin release and subsequent
INDGMETHACIN
AND CAPTOPRIL
ON NEPHRECTOMY
-I Control
50%
Nx
-I Nx+cap
Nx+ind
Nx+cap +ind
control +PG
Nx+PG
Nx+ind +PG
Treatment FIG. 2. Effects of 50% nephrectomy, captopril, indomethacin, and/or prostaglandin E, on effective renal plasma flow (ERPF) (CT& and glomerular filtration rate (Cinulln) , expressed per gram kidney weight, in rats. Captopril-treated nephrectomized rats experienced a significant (p < 0.05) increase (*) in ERPF compared to the control group. Control, sham operated; 50% Nx, uninephrectomy; cap, captopril: ind. indomethacin; PG, prostaglandin E, ; effective renal plasma flow: I, glomerular filtration rate.
+ ContrOt
50%
Nx NX+Cap
Nx+ind
Nx+cap +Ind
control Nx+PG +PG
4 NX+lnd +PG
Treatment
FIG. 3. Effects of 50% nephrectomy, captopril, indomethacin, and/or prostaglandin E, on renal vascular resistance (RVR) in rats. Captopril-treated nephrectomized rats experienced a significant (p < 0.05) decrease (*) in RVR compared to the control group. Indomethacin-treated nephrectomized rats experienced a significant (p < 0.05) increase (t) in RVR compared to the uninephrectomy group. Control. sham operated: 50% Nx, uninephrectomy: cap, captopril; ind, indomethacin; PC, prostaglandin E,
36
FETTMAN
AND WILKE
z
6.0
z m
6.0
3
5.0
z
6.0
4.0
p” :: i0
4.0
CD
6 2 Ya 9 E m %
3.0
9 E
3.0
2.0
_a D
2.0
ff
1 .o
f
1 .o
B
s
0.0
0.0 NX and
Nx+lnd and
Nx+PG
Nx+ind+PG
Nx+cap+ind
Nx+cap Treatment
Treatment
FIG. 4. Effects of captopril and/or indomethacin on remnant kidney weight in 50% nephrectomized rats. Data from rats receiving PGE, infusion are pooled with those who did not, as this would not have affected residual renal hypertrophy. Nx, uninephrectomy; ind, indomethacin; cap, captopril; PG, prostaglandin El.
angiotensin II activation, following cyclooxygenase inhibition (Chevalier et al., 1987). In the present study of adult rats at normal systemic blood pressure, indomethacin-induced increases in RVR were muted by acute infusion of prostaglandin El. This occurred despite the inevitable stimulation of renin release by the infused prostaglandin (Suzuki et al., 198 1). Indomethacin’s effect on RVR was attenuated by conjoint treatment with captopril. In anesthetized, sodium-restricted dogs, indomethacin increased RVR and systemic arterial blood pressure and decreased ERPF and GFR (Carmines et al., 198 3). Subsequent captopril treatment was shown to decrease RVR and systemic blood pressure and to increase ERPF and GFR, suggesting the renal response to captopril is not mediated by alterations in prostaglandin synthesis, but due to reductions in angiotensin II (Carmines et al., 1983). Likewise, in conscious dogs pretreated with indomethacin, ERPF, GFR, urinary sodium excretion, and plasma renin activity were increased following conjoint captopril administration (DeForrest et al., 1982). Together with the present study, these findings support concurrent and opposite roles for angiotensin II and vasodilatory prostanoids in the control of remnant kidney vascular resis-
tance in unanesthetized, 50% nephrectomized rats. Alterations in FF concur with this interpretation; indomethacin increased FF, while captopril counteracted this effect. Indomethacin enhanced compensatory renal growth, but despite increased ERPF, captopril had no such effect. Thus, in this shortterm model, renal compensatory growth appeared not to be dependent on renal vasodilation or increments in blood flow. The clinical relevance of this observation is speculative. Absence of other significant effects of indomethacin or PGE, in normal and nephrectomized rats in this study conflicts in part with previous findings in anesthetized animals following removal of larger amounts of kidney and studied for a longer period of time. This may be attributed to confounding effects of anesthesia in other studies, where reduced arterial pressure, increased renal vascular resistance, and increased renal prostanoid release have been documented (Walker et al., 1986), and/or to insufficient dosage of drugs in the present study. In the nephrectomized rats, minimal drug effects may additionally have been due to the minimal remnant nephron damage following only 50% nephrectomy and/or 7 days of compensatory changes. Subtle physiological changes ob-
INDOMETHACIN
AND CAPTOPRIL
served in this study may chronically accentuate or advance renal dysfunction. Adverse effects of indomethacin in rats with minimal renal compromise demonstrate the propensity for exacerbation of subclinical renal disease in human beings receiving nonsteroidal anti-inflammatory drugs. One may speculate that longer term treatment would elicit more overt signs of renal dysfunction. Likewise, the apparent ameliorative effects of concurrent captopril treatment might delay those effects over a longer period of time, but this should be studied further. Additional studies should address the potential problems identified above, particularly effects of anesthesia on clearance functions and greater remnant nephron damage following 75% nephrectomy and/or longer periods of compensation. Concurrent therapy with angiotensin-converting enzyme inhibitors and nonsteroidal anti-inflammatory drugs should be approached with caution in renal disease, owing to inhibition of beneficial effects of the former by the latter. Conversely, and most importantly, angiotensinconverting enzyme inhibitors may moderate adverse renal effects of nonsteroidal anti-inflammatory drugs administered by necessity to patients with renal disease. ACKNOWLEDGMENTS The investigators express appreciation to E. R. Squibb and Sons, Inc., for the donation of captopril and to the Upjohn Co. for the donation of Prostin VR (alprostadil) for use in these studies.
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ON NEPHRECTOMY
37
contributions of prostaglandin stimulation and suppressed angiotensin activity. Renal Physiol. 6, 281287. CHEVALIER. R. L., CAREY, R. M., AND KAISER, D. L. ( 1987). Endogenous prostaglandins modulate autoregulation of renal blood flow in young rats. Amer. J. Physiol. 253, F66-F75. CHEVALIER, R. L., AND KAISER, D. L. (1985). Effects of acute uninephrectomy and age on renal blood flow autoregulation in the rat. Amer. J. Physiol. 249, F672F679. CHRYSANT, S. G. (1978). Renal functional changes induced by prostaglandin E 1 and indomethacin on the anesthetized dog. Arch. Int. Pharmacodyn. Ther. 234, 156-163. CLAPPISON, B. H., ANDERSON, W. P., AND JOHNSTON, C. I. (198 I). Renal hemodynamics and renal kinins after angiotensin converting enzyme inhibition. Kidney Int. 20,6 15-620. DEFORREST, J. M., WALDRON, T. L.. AND ANTONACCIO, M. J. (1982). Renal response to captopril in conscious dogs pretreated with indomethacin. Amer J Physiol.
243, G543-G548.
DUNN, M. J., AND ZABRASKI, E. J. (1980). Renal effects of drugs that inhibit prostaglandin synthesis. Kidney Int. l&609-622.
HALL, R. L., WILKE, W. L., AND FETTMAN, M. J. (1985). Captopril slows the progression of chronic renal disease in partially nephrectomized rats. Toxicol. .4ppl. Pharmacol. 80,5 17-526. HALL, R. L., WILKE, W. L., AND FETTMAN, M. J. ( 1986a). The progression of adriamycin-induced nephrotic syndrome in rats and the effect of captopril. Toxicol. Appl. Pharmacol. 82, 164- 174. HALL, R. L., WILKE, W. L., AND FETTMAN, M. J. (1986b). Effect of captopril on the progression of experimentally-induced pyelonephritis in the rat. Amer. J. Vet. Res. 47, 1085-1088.
HEEG, J. E.. DE JONG, P. E., VAN DER HEM, G. K., AND DE ZEEUW, D. (1987). Reduction of proteinuria by angiotensin converting enzyme inhibition. Kidney Int. 32,78-83. JACKSON, E. K., HEIDEMANN. H. T., BRANCH, R. A., AND GERKENS, J. F. (1982). Low dose intrarenal infusions of PGEZ, PGI2, and 6-keto-PGEI vasodilate the in vivo rat kidney. Circ. Res. S&67-72. KAIZU. K., MARSH, D.. ZIPSER, R., AND GLASSOCK, R. J. (1985). Role of prostanoids and angiotensin II in experimental glomerulonephritis. Kidney Int. 28. 629-635. KASTNER, P. R., HALL, J. E., AND GUYTON, A. C. (1984). Control of glomerular filtration rate: Role of intrarenally formed angiotensin II. Amer. J. Physiol. 246, F897-F906. NAVAR, I. G., AND ROSIWALL, L. ( 1984). Contribution of the renin-angiotensin system to the control of intrarenal hemodynamics. Kidney Int. 25,857-868.
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RADIN, M. J., WILKE, W. L., AND FETTMAN, M. J. (1986a). Effects of captopril on chronic puromycin aminonucleoside nephrosis in rats. Rex Commun. Chem. Pathol. Pharmacol. 54,219-282. RADIN, M. J., FETTMAN, M. J., AND WILKE, W. L. (1986b). Single injection method for evaluation of renal function with 3H-inulin and ‘%-tetraethylammonium bromide in conscious, unrestrained SpragueDawley rats. J. Amer. Vet. Med. Assoc. 189, 10441046. RADIN, M. J., WILKE, W. L., AND FETTMAN, M. J. (I 987). Effect ofpropranolol on progression of chronic renal disease in partially nephrectomized rats. Res. Commun. Chem. Pathol. Pharmacol. 57,3- 13. STAHL, R. A. K., KUDELKA, S., PARAVICINI, M., AND SCHOLLMEYER, P. (1986). Prostaglandin and throm-
AND WILKE boxane formation in glomeruli form rats with reduced renal mass. Nephron 42,252-257. STEEL, R. G. D., AND TORRIE, J. H. ( 1980). In Principles and Procedures of Statistics, 2nd ed. McGraw-Hill, New York. SUZUKI, S., FRANCO-SAENZ, R., TAN, S. Y., AND MUL ROW, P. J. (198 1). Effects of indomethacin on plasma renin activity in the conscious rat. Amer. J. Physiol. 240, E286-E289. WALKER, L. A., GELLAI, M., AND VALTIN, H. (1986). Renal response to pentobarbital anesthesia in rats: Effect of interrupting the renin-angiotensin system. J. Pharmacol. Exp. Ther. 236,72 l-728. YOSHIDA, M., UEDA, S., SOEJIMA, H., TSURUTA, K., AND IREGAMI, K. ( 1986). Effects of prostaglandin E2 and I2 on renal cortical and medulhuy blood flow in rabbits. Arch. Int. Pharmacodyn. Ther. 282,108-l 1I.