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Effects of kidney transplantation on the renin-angiotensin systems of the recipients
Kidney International, Vol. 46 (1994), pp. 1536—1538
Effects of kidney transplantation on the renin-angiotensin systems of the recipients RAINER RETTIG, MARINA BUCH, RUDIGER GERSTBERGER, PETER SCHNATFERBECK, and MARTIN PAUL Depamnent of Pharmacology University of Heidelberg Heidelberg, and Max-Planck-Institute for Physiological and Clinical Research, Kerckhoff Institute, Bad Nauheim, Germany
Effects of kidney transplantation on the renin-angiotensin systems of the recipients. To investigate the effects of renal transplantation on the plasma and local kidney renin-angiotensin systems of the recipients the left kidneys of 13 adult male Wistar-Kyoto rats (WKY) and 13 strokeprone spontaneously hypertensive rats (SHRSP) were transplanted to bilaterally nephrectomized (WKYxSHRSP)-F1 hybrids. Nine unilaterally nephrectomized WKY and nine SHRSP served as controls. Four weeks after surgery recipients of an SHRSP kidney but not recipients of a WKY kidney had significant post-transplantation hypertension. Plasma renin activity (PRA) was higher in SHRSP than in WKY. Transplanted rats had lower PRAs than nontranspianted controls. Plasma ACE activity was lowest in SHRSP, intermediate in transplanted Fl hybrids and highest in WKY. Plasma Ang I and Ang II concentrations closely paralleled each other. They were not significantly different between WKY and SHRSP and lower in transplanted than in nontransplanted rats. ACE and renin mRNA were lower in transplanted than in nontransplanted kidneys. Glomerular angiotensin II receptor density was higher in transplanted than in nontransplanted kidneys with no significant differences between strains. We conclude that renal transplantation has profound long-term
Methods The left kidneys of 13 adult male WKY and 13 SHRSP were transplanted as previously described [4] to bilaterally nephrecto-
mized Fl hybrids bred from WKY and SHRSP parents. Nine
unilaterally nephrectomized SHRSP served as controls. Animals were maintained under standard conditions with access to standard laboratory rat food and tape water ad libitum. Four weeks after surgery, rats were sacrificed by rapid bleeding under ether
anesthesia. Blood was centrifuged and plasma was stored at —20°C for later determinations of plasma renin activity (PRA), angiotensin I converting enzyme (ACE) activity, angiotensin I (Ang I) concentration, and angiotensin II (Ang II) concentration. Renal grafts and nontransplanted solitary control kidneys were rapidly removed without perfusion and cut in halves. One half was
immediately processed for Ang II receptor binding studies in
isolated glomeruli using increasing concentrations of [1251]Ang II. effects on the recipients' plasma and local kidney renin-angiotensin The other half was frozen in liquid nitrogen and stored at —80°C systems. These do not appear to be involved in the pathogenesis of for later determinations of specific mRNAs for angiotensinogen, post-transplantation hypertension in recipients of an SHRSP kidney, but may reflect a role for the intrarenal renin-angiotensin system in long-term renal adaptation and repair processes after transplantation.
renin, and ACE. Total RNA was extracted using the acid guanidinium-thiocyanate-phenol-chloroform method. Specific mRNAs were detected by Southern blot analysis following reverse transcription and PCR amplification using semiquantitative techniques.
Results Four weeks after transplantation systolic blood pressure was
In renal transplantation experiments with stroke-prone sponta-
neously hypertensive rats (SHRSP) and normotensive WistarKyoto rats (WKY) as kidney donors, recipients of an SHRSP kidney developed post-transplantation hypertension [1]. This effect was not due to the procedure of renal transplantation as such since recipients of a WKY kidney remained normotensive. Further renal transplantation studies with young prehypertensive SHRSP [2] indicated that a genetically determined alteration to the kidney likely contributed to post-transplantation hypertension. The nature of this alteration remains unclear. The reninangiotensin system could be a possible candidate since it is known to be intricately involved in renal physiology and pathophysiology [3]. The present study was designed to investigate the effects of transplantation of WKY and SHRSP kidneys, respectively, on the recipients' plasma and local renin-angiotensin systems.
© 1994 by the International Society of Nephrology
126 7 mm Hg in Fl hybrids that had received a WKY kidney and 184 8 mm Hg in recipients of an SHRSP kidney (P < 0.01). These values corresponded well to the systolic blood pressures in unilaterally nephrectomized rats of the donor strains (WKY, 118
5 mm Hg; SHRSP, 193 7 mm Hg). Glomerular Ang II receptor density increased from 136 31 fmollmg protein in nontransplanted solitary WKY kidneys to 276 49 fmol/mg protein in transplanted WKY kidneys (P < 0.05) and from 147 24 fmol/mg protein in nontranspianted SHRSP kidneys to 332 54 fmol/mg protein in transplanted SHRSP kidneys (P < 0.05). There were no significant differences in glomerular Ang II receptor density between nontranspianted WKY and SHRSP kidneys and between renal grafts from both strains. [1251]Ang II binding affinity was similar in all groups regardless of strain and transplantation. PRA (Fig. 1) was higher in SHRSP than in WKY. Bilaterally nephrectomized rats with a renal graft had significantly lower PRAs than nontransplanted rats. PRA was higher in recipients of
1536
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Rettig et a!: RAS and transplantation
8
1000
C Angiotensiri I
x E C)
E 0
4
500
E
1
0 E
a 0
0
WKY SHRSP
F1H
F1H
WKY SHRSP
Hh F1H
F1H
(WKY) (SHRSP)
(WKY) (SHRSP)
50
800 B ACE activity
Angiotensin II
x E a) -J
I0
E
*
400
0 E
() E
C
0
H
WKY SHRSP
*
25
0 F1H
F1H
(WKY) (SHRSP)
WKY SHRSP
H F1H
F1H
(WKY) (SHRSP)
Fig. 1. Plasma renin activity (A), plasma ACE activity (B), plasma angiotensin I concentration (C), and plasma angiotensin II concentration (D) in unilaterally nephrectomized WKY and SHRSP and in Fl hybrids (F1H) with a solitaty transplanted kidney from WKY and SHRSP donors, respectively, four weeks after surgely. # P < 0.05 versus WKY; * P < 0.05 versus donor strain group. N = 9 to 13 for each measure.
The finding that bilateral nephrectomy and transplantation of an SHRSP kidney than in recipients of a WKY kidney. Plasma ACE activity (Fig. 1) was highest in WKY, lowest in SHRSP and an SHRSP kidney resulted in severe post-transplantation hyperintermediate in Fl hybrids. There were no significant differences tension is in keeping with previous reports [reviewed in 1]. The in plasma ACE activity between recipients of an WKY and same holds true for the observation that blood pressure did not SHRSP kidney. Plasma Ang I and Ang II concentrations (Fig. 1) change significantly in recipients of a WKY kidney. The mechaclosely paralleled each other. There were no significant differ- nisms by which a transplanted SHRSP kidney causes hypertension ences in both parameters between WKY and SHRSP. Fl hybrid in the recipient are currently unknown. The local kidney reninrecipients had lower plasma Ang I and Ang II concentrations than angiotensin system may be involved in hypertension by various rats in the donor strain groups with no significant differences mechanisms [5]. between recipients of a WKY and SHRSP kidney. In the present study the only statistically significant difference Renal angiotensinogen mRNA (Fig. 2) was not significantly between WKY and SHRSP with respect to the renal renindifferent between WKY and SHRSP and between transplanted angiotensin system was a higher renin mRNA in SHRSP than in and nontransplanted kidneys. Renal renin mRNA (Fig. 2) was WKY kidneys. This finding corresponds well to our observation of higher in SHRSP than in WKY. It decreased in both strains in a significantly elevated PRA in adult SHRSP compared to WKY. transplanted versus nontranspianted kidneys. There were no It has recently been shown that circulating renin in SHRSP significant differences between transplanted WKY and SHRSP increases with age and that it is significantly elevated over kidneys. Renal ACE mRNA (Fig. 2) was not significantly different circulating renin in WKY in animals aged 18 weeks and older [6}. between WKY and SHRSP. It decreased significantly in trans- All other parameters of the plasma and local kidney reninplanted versus nontranspianted kidneys in both strains. angiotensin systems measured in this study were not significantly different between WKY and SHRSP. However, some were proDiscussion foundly affected by renal transplantation. Renal renin and ACE mRNA were significantly lower in The major finding of the present study is that renal transplantation has profound effects on the recipients' plasma and local transplanted than in nontransplanted kidneys of either strain. This kidney renin-angiotensin systems with no significant differences does not reflect a general down-regulation of the local reninbetween recipients of a WKY and SHRSP kidney. angiotensin system after transplantation since angiotensinogen
1538
Rettig et a!: RAS and transplantation
9
6 C
3
0
5 4
0
3
C
2
0
mRNA was not significantly altered and Ang II receptor density was increased in grafted versus native kidneys. The decrease in renal renin mRNA was associated with a lower PRA in transplanted than in nontranspianted rats. Interestingly, the difference in PRA between WKY and SHRSP was maintained in recipients of kidneys from these strains. As expected, plasma ACE activity in transplanted rats did not follow the alterations of renal ACE mRNA, but reflected the genetic background of the recipients.
The alterations of the components of the renin-angiotensin system as described above led to a significant decrease in the plasma concentration of the effector peptide Ang II in transplanted versus nontransplanted rats. This observation together with the finding that plasma Ang II concentrations were similar in recipients of a WKY and SHRSP kidney exclude the circulating renin-angiotensin system as a causative factor for post-transplantation hypertension in recipients of an SHRSP kidney.
Taken together, our data indicate that neither the circulating nor the local kidney renin-angiotensin system contribute to posttransplantation hypertension in recipients of an SFIRSP kidney. The alterations of renal renin and ACE mRNA as well as Ang II receptor density after transplantation may reflect a role for the intrarenal renin-angiotensin system in long-term adaptation and repair processes in renal grafts.
Reprint requests to Rainer Rettig, M.D., Department of Physiology, ErnstMoritz-Arndt-University, Rubenowstrasse 3, D-17487 Greifswald, Germany.
6 References
4 0 C
2
1. RerriG R, SCHM!Tr B, PELZL B, SPECK T: The kidney and primary hypertension. Contributions from renal transplantation studies in animals and humans. J Hypertens 11:883—891, 1993 2. KOPF D, WALDFIERR R, RErrIG R: Source of kidney determines blood pressure in young renal transplanted rats. Am JPhysiol 265:F104—F1 11, 1993
3. JOHNSTON CI, FuRis B, JANDELEIT K: Intrarenal renin-angiotensin system in renal physiology and pathophysiology. Kidney mt 44(Suppl
0 Control Transplanted 2. Angiotensinogen mRNA, renin mRNA, and ACE mRNA in nonFig. transplanted and transplanted solitary WKY (Dl) and SHRSP ( kidneys four weeks after surgery for contralateral nephrectomy or renal transplantation, respectively. # P < 0.05 versus WKY; * P < 0.05 versus nontransplanted control kidneys of the same strain. N = 9 to 13.
42):S-59—S-63, 1993 4. Gits.s' C, MASER-GLUTH C, DE MUINCK KEIZER W, RETFIG R: Renal
sodium retention in posttransplant hypertensive recipients of SHRSP kidneys. Hypertension 21:724—730, 1993 5. KRIEGER JE, DZAU VJ: Molecular biology of hypertension. Hypertension 18(Suppl I):I-3—I-17, 1991 6. KIM 5, TOKUYAMA M, Hosoi M, YArvi.&rvioTo K: Adrenal and circulating renin-angiotensin system in stroke-prone hypertensive rats. Hypertension 20:280—291, 1992
Effects of kidney transplantation on the renin-angiotensin systems of the recipients RAINER RETTIG, MARINA BUCH, RUDIGER GERSTBERGER, PETER SCHNATFERBECK, and MARTIN PAUL Depamnent of Pharmacology University of Heidelberg Heidelberg, and Max-Planck-Institute for Physiological and Clinical Research, Kerckhoff Institute, Bad Nauheim, Germany
Effects of kidney transplantation on the renin-angiotensin systems of the recipients. To investigate the effects of renal transplantation on the plasma and local kidney renin-angiotensin systems of the recipients the left kidneys of 13 adult male Wistar-Kyoto rats (WKY) and 13 strokeprone spontaneously hypertensive rats (SHRSP) were transplanted to bilaterally nephrectomized (WKYxSHRSP)-F1 hybrids. Nine unilaterally nephrectomized WKY and nine SHRSP served as controls. Four weeks after surgery recipients of an SHRSP kidney but not recipients of a WKY kidney had significant post-transplantation hypertension. Plasma renin activity (PRA) was higher in SHRSP than in WKY. Transplanted rats had lower PRAs than nontranspianted controls. Plasma ACE activity was lowest in SHRSP, intermediate in transplanted Fl hybrids and highest in WKY. Plasma Ang I and Ang II concentrations closely paralleled each other. They were not significantly different between WKY and SHRSP and lower in transplanted than in nontransplanted rats. ACE and renin mRNA were lower in transplanted than in nontransplanted kidneys. Glomerular angiotensin II receptor density was higher in transplanted than in nontransplanted kidneys with no significant differences between strains. We conclude that renal transplantation has profound long-term
Methods The left kidneys of 13 adult male WKY and 13 SHRSP were transplanted as previously described [4] to bilaterally nephrecto-
mized Fl hybrids bred from WKY and SHRSP parents. Nine
unilaterally nephrectomized SHRSP served as controls. Animals were maintained under standard conditions with access to standard laboratory rat food and tape water ad libitum. Four weeks after surgery, rats were sacrificed by rapid bleeding under ether
anesthesia. Blood was centrifuged and plasma was stored at —20°C for later determinations of plasma renin activity (PRA), angiotensin I converting enzyme (ACE) activity, angiotensin I (Ang I) concentration, and angiotensin II (Ang II) concentration. Renal grafts and nontransplanted solitary control kidneys were rapidly removed without perfusion and cut in halves. One half was
immediately processed for Ang II receptor binding studies in
isolated glomeruli using increasing concentrations of [1251]Ang II. effects on the recipients' plasma and local kidney renin-angiotensin The other half was frozen in liquid nitrogen and stored at —80°C systems. These do not appear to be involved in the pathogenesis of for later determinations of specific mRNAs for angiotensinogen, post-transplantation hypertension in recipients of an SHRSP kidney, but may reflect a role for the intrarenal renin-angiotensin system in long-term renal adaptation and repair processes after transplantation.
renin, and ACE. Total RNA was extracted using the acid guanidinium-thiocyanate-phenol-chloroform method. Specific mRNAs were detected by Southern blot analysis following reverse transcription and PCR amplification using semiquantitative techniques.
Results Four weeks after transplantation systolic blood pressure was
In renal transplantation experiments with stroke-prone sponta-
neously hypertensive rats (SHRSP) and normotensive WistarKyoto rats (WKY) as kidney donors, recipients of an SHRSP kidney developed post-transplantation hypertension [1]. This effect was not due to the procedure of renal transplantation as such since recipients of a WKY kidney remained normotensive. Further renal transplantation studies with young prehypertensive SHRSP [2] indicated that a genetically determined alteration to the kidney likely contributed to post-transplantation hypertension. The nature of this alteration remains unclear. The reninangiotensin system could be a possible candidate since it is known to be intricately involved in renal physiology and pathophysiology [3]. The present study was designed to investigate the effects of transplantation of WKY and SHRSP kidneys, respectively, on the recipients' plasma and local renin-angiotensin systems.
© 1994 by the International Society of Nephrology
126 7 mm Hg in Fl hybrids that had received a WKY kidney and 184 8 mm Hg in recipients of an SHRSP kidney (P < 0.01). These values corresponded well to the systolic blood pressures in unilaterally nephrectomized rats of the donor strains (WKY, 118
5 mm Hg; SHRSP, 193 7 mm Hg). Glomerular Ang II receptor density increased from 136 31 fmollmg protein in nontransplanted solitary WKY kidneys to 276 49 fmol/mg protein in transplanted WKY kidneys (P < 0.05) and from 147 24 fmol/mg protein in nontranspianted SHRSP kidneys to 332 54 fmol/mg protein in transplanted SHRSP kidneys (P < 0.05). There were no significant differences in glomerular Ang II receptor density between nontranspianted WKY and SHRSP kidneys and between renal grafts from both strains. [1251]Ang II binding affinity was similar in all groups regardless of strain and transplantation. PRA (Fig. 1) was higher in SHRSP than in WKY. Bilaterally nephrectomized rats with a renal graft had significantly lower PRAs than nontransplanted rats. PRA was higher in recipients of
1536
1537
Rettig et a!: RAS and transplantation
8
1000
C Angiotensiri I
x E C)
E 0
4
500
E
1
0 E
a 0
0
WKY SHRSP
F1H
F1H
WKY SHRSP
Hh F1H
F1H
(WKY) (SHRSP)
(WKY) (SHRSP)
50
800 B ACE activity
Angiotensin II
x E a) -J
I0
E
*
400
0 E
() E
C
0
H
WKY SHRSP
*
25
0 F1H
F1H
(WKY) (SHRSP)
WKY SHRSP
H F1H
F1H
(WKY) (SHRSP)
Fig. 1. Plasma renin activity (A), plasma ACE activity (B), plasma angiotensin I concentration (C), and plasma angiotensin II concentration (D) in unilaterally nephrectomized WKY and SHRSP and in Fl hybrids (F1H) with a solitaty transplanted kidney from WKY and SHRSP donors, respectively, four weeks after surgely. # P < 0.05 versus WKY; * P < 0.05 versus donor strain group. N = 9 to 13 for each measure.
The finding that bilateral nephrectomy and transplantation of an SHRSP kidney than in recipients of a WKY kidney. Plasma ACE activity (Fig. 1) was highest in WKY, lowest in SHRSP and an SHRSP kidney resulted in severe post-transplantation hyperintermediate in Fl hybrids. There were no significant differences tension is in keeping with previous reports [reviewed in 1]. The in plasma ACE activity between recipients of an WKY and same holds true for the observation that blood pressure did not SHRSP kidney. Plasma Ang I and Ang II concentrations (Fig. 1) change significantly in recipients of a WKY kidney. The mechaclosely paralleled each other. There were no significant differ- nisms by which a transplanted SHRSP kidney causes hypertension ences in both parameters between WKY and SHRSP. Fl hybrid in the recipient are currently unknown. The local kidney reninrecipients had lower plasma Ang I and Ang II concentrations than angiotensin system may be involved in hypertension by various rats in the donor strain groups with no significant differences mechanisms [5]. between recipients of a WKY and SHRSP kidney. In the present study the only statistically significant difference Renal angiotensinogen mRNA (Fig. 2) was not significantly between WKY and SHRSP with respect to the renal renindifferent between WKY and SHRSP and between transplanted angiotensin system was a higher renin mRNA in SHRSP than in and nontransplanted kidneys. Renal renin mRNA (Fig. 2) was WKY kidneys. This finding corresponds well to our observation of higher in SHRSP than in WKY. It decreased in both strains in a significantly elevated PRA in adult SHRSP compared to WKY. transplanted versus nontranspianted kidneys. There were no It has recently been shown that circulating renin in SHRSP significant differences between transplanted WKY and SHRSP increases with age and that it is significantly elevated over kidneys. Renal ACE mRNA (Fig. 2) was not significantly different circulating renin in WKY in animals aged 18 weeks and older [6}. between WKY and SHRSP. It decreased significantly in trans- All other parameters of the plasma and local kidney reninplanted versus nontranspianted kidneys in both strains. angiotensin systems measured in this study were not significantly different between WKY and SHRSP. However, some were proDiscussion foundly affected by renal transplantation. Renal renin and ACE mRNA were significantly lower in The major finding of the present study is that renal transplantation has profound effects on the recipients' plasma and local transplanted than in nontransplanted kidneys of either strain. This kidney renin-angiotensin systems with no significant differences does not reflect a general down-regulation of the local reninbetween recipients of a WKY and SHRSP kidney. angiotensin system after transplantation since angiotensinogen
1538
Rettig et a!: RAS and transplantation
9
6 C
3
0
5 4
0
3
C
2
0
mRNA was not significantly altered and Ang II receptor density was increased in grafted versus native kidneys. The decrease in renal renin mRNA was associated with a lower PRA in transplanted than in nontranspianted rats. Interestingly, the difference in PRA between WKY and SHRSP was maintained in recipients of kidneys from these strains. As expected, plasma ACE activity in transplanted rats did not follow the alterations of renal ACE mRNA, but reflected the genetic background of the recipients.
The alterations of the components of the renin-angiotensin system as described above led to a significant decrease in the plasma concentration of the effector peptide Ang II in transplanted versus nontransplanted rats. This observation together with the finding that plasma Ang II concentrations were similar in recipients of a WKY and SHRSP kidney exclude the circulating renin-angiotensin system as a causative factor for post-transplantation hypertension in recipients of an SHRSP kidney.
Taken together, our data indicate that neither the circulating nor the local kidney renin-angiotensin system contribute to posttransplantation hypertension in recipients of an SFIRSP kidney. The alterations of renal renin and ACE mRNA as well as Ang II receptor density after transplantation may reflect a role for the intrarenal renin-angiotensin system in long-term adaptation and repair processes in renal grafts.
Reprint requests to Rainer Rettig, M.D., Department of Physiology, ErnstMoritz-Arndt-University, Rubenowstrasse 3, D-17487 Greifswald, Germany.
6 References
4 0 C
2
1. RerriG R, SCHM!Tr B, PELZL B, SPECK T: The kidney and primary hypertension. Contributions from renal transplantation studies in animals and humans. J Hypertens 11:883—891, 1993 2. KOPF D, WALDFIERR R, RErrIG R: Source of kidney determines blood pressure in young renal transplanted rats. Am JPhysiol 265:F104—F1 11, 1993
3. JOHNSTON CI, FuRis B, JANDELEIT K: Intrarenal renin-angiotensin system in renal physiology and pathophysiology. Kidney mt 44(Suppl
0 Control Transplanted 2. Angiotensinogen mRNA, renin mRNA, and ACE mRNA in nonFig. transplanted and transplanted solitary WKY (Dl) and SHRSP ( kidneys four weeks after surgery for contralateral nephrectomy or renal transplantation, respectively. # P < 0.05 versus WKY; * P < 0.05 versus nontransplanted control kidneys of the same strain. N = 9 to 13.
42):S-59—S-63, 1993 4. Gits.s' C, MASER-GLUTH C, DE MUINCK KEIZER W, RETFIG R: Renal
sodium retention in posttransplant hypertensive recipients of SHRSP kidneys. Hypertension 21:724—730, 1993 5. KRIEGER JE, DZAU VJ: Molecular biology of hypertension. Hypertension 18(Suppl I):I-3—I-17, 1991 6. KIM 5, TOKUYAMA M, Hosoi M, YArvi.&rvioTo K: Adrenal and circulating renin-angiotensin system in stroke-prone hypertensive rats. Hypertension 20:280—291, 1992