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Renal and Systemic, Circulatory and Metabolic Alterations after Intravenous Glucose Loads in Baboons
Vol. 101, Apr· Printed in U.S.A·
THE JOURNAL OF UROLOGY
Copyright © 1969 by The Williams & Wilkins Co.
RENAL AND SYSTEMIC, CIRCULATORY AND METABOLIC ALTERATIONS AFTER INTRAVENOUS GLUCOSE LOADS IN BABOONS G. F. ROHM, C. P. RETIEF, G. s. JOHNSTON, J. A. VAN ZYL, J. J. w. VAN ZYL, J. N. DEKLERK AND G. P. MURPHY* From the Family of lvI eclicine, University of Stellenbosch, Karl Breiner H Ospital, Bellville, South Africa; the Radioisotope Service, Waller Reecl General Hospital, Washington, D. C. and the Regional Kidney Center, Roswell Park Memorial Institute, Buffalo, New York
Renal function studies were performed with intravenous glucose loads to facilitate diuresis in a renal allotransplantation project jointly undertaken by the University of Stellenbosch and the Johns Hopkins Hospital. Glucose given by intravenous infusion over a short period can produce marked alterations in systemic and renal circulatory and electrolyte metabolism. This effect has been partially described in other species1 and until now the accepted explanation has been that the glucose infusion induces a sudden increase in plasma osmolality. The consequent shift of water from the intracellular to the extracellular fluid compartment was thought to result in an increase in plasma volume. The observed reductions in plasma sodium and chloride levels were attributed to the dilution which occurs. In addition, owing to the osmotic effect of the resulting glucosuria and the increased plasma volume, a diuresis occurs which can result in further salt loss. This phenomenon may have clinical significance. It has been observed that patients in a state of diabetic hyperglycemia, azotemia or patients in whom glucose or other osmotically active particles have been acutely administered1- 4 respond in an apparently similar manner. Accepted for publication March 4, 1968. This study was supported by the Council for Scientific and Industrial Research, the Cape Provincial Administration, the University of Stellenbosch, and private donations from the Brady Urological Institute, Johns Hopkins Hospital and from the Baxter Laboratories, JVIorton Grove, Illinois. * Reprint Requests: 666 Elm Street, Buffalo, New York 14203. 1 Seldin, D. W. and Tarail, R.: Effect of hypertonic solutions on metabolism and excretion of electrolytes. Amer. J. Physiol., 159: 160, 1949. 2 Goldberger, E.: A Primer of Water, Electrolyte and Acid-Base Syndromes. Philadelphia: Lea & Febiger, 3rd ed., 1965. 3 Hoffman, W. S.: The Biochemistry of Clinical Medicine. Chicago: The Year Book Medical Publishers, 3rd ed., 1964. 4 Weisberg, H. F.: Pitfalls in fluid and electrolyte therapy. Yena,, 1: 107, 1964.
The series of experiments reported herein were performed on baboons which were either intact or had been subjected to adrenalectomy or bilateral nephrectomy. The object was to determine the precise cause of the sequential electrolyte shifts which occur after the administration of glucose loads and to relate these shifts to the observed alterations in renal and systemic hemodynamics. MATERIALS AND METHODS
Twenty-four healthy, adult male and female baboons (Papio ursinus or Chacma baboon) weighing 8.1 to 28.7 kg., were divided into 5 experimental groups. The baboons were given phencyclidine hydrochloridet (1 mg./kg.) and a urethral catheter was inserted. During an observation period each animal received an intravenous infusion of 700 ml. 5 per cent glucose in water (35 gm.). Blood specimens were taken by femoral or peripheral vein puncture. Group 1 (17 animals): After obtaining basal blood and urine specimens within 10 to 20 minutes, the intravenous glucose infusion was given over a period of 45 minutes. Three further blood and urine samples were taken at 15-minute intervals. Group 2 (3 animals): In addition to the samples drawn as described in group 1, 10 ml. heparinized femoral vein blood was obtained and centrifuged. The erythrocytes from each animal were labeled with 10 to 30 µc 51 chromiurn (51 Cr). Free or excess 51 Cr was removed by repeated washing, and the labeled red cells were again suspended in the plasma obtained on centrifugation. This sample was then injected intravenously and after a 20-minute mixing period, 5 ml. venous blood was withdrawn and the red cell mass, plasma and total blood volumes were calculated using a well counter.t Sixty minutes after infusion of the
460
t Sernylan, Parke Davis, Co., Detroit, Michigan. t Picker well counter, donated by S. A. Atomic Energy Board.
461
INTRAVENOUS GLUCOSE IN BABOONS
initial glucose load was completed, these estimations were repeated. Hemoglobin concentration and mean cell hemoglobin concentration (MCHC) were recorded. Urine samples were collected before and for a 2;!,'i-hour period after the glucose infusion. Group 3 (1 animal) : This animal was studied for 3 consecutive days with repeated intravenous glucose loads similar to those given the animals in group 1. On the fourth morning a bilateral adrenalectomy was done. On that day and for 2 additional days the studies were repeated. Group 4 (1 animal): This animal was initially subjected to tests similar to those used on the animals in group 1. On the following day bilateral nephrectomy was performed and on 2 subsequent days the same studies were repeated, except for the urine collections. Group 5 (2 animals): The studies described for group 1 were again carried out, except hourly blood and urine samples were collected up to 8 hours after the infusion. In all groups except group 4, blood serum and urine specimens were obtained for clearance of para-aminohippuric acid (CPAH), endogenous creatinine clearance (CcR), osmolar clearance (CosM) and free water clearance. Sodium, chloride, potassium, protein, glucose, urea and cholesterol levels were also determined. To minimize the blood losB resulting from the many samples withdrawn, micro-chemical methods of determination were used. On an average 8 ml. blood was withdrawn for each sample. PAH levels were maintained by the infusion of 5 per cent glucose in water at a rate of 3 ml. per minute. Renal plasma flows were calculated with the usual correction for hematocrit. Determination of blood gases p02, pC02 and pH were performed in some instances. All data were statistically evaluated with the aid of a desk top computer.* The principles and practices of the South African Animal Welfare Society and American National Society for Medical Research were observed throughout these experiments. RESULTS
Table 1 shows the changes that occur in the blood and urine of baboons after a high dose of intravenous glucose over a short period. An osmotic diuresis is associated with a fall in * Olivetti Programma Town, South Africa.
101 computer,
Cape
1. Renal and systemic alterations after intravenous glucose loads in intact baboons. (Group 1 and preoperative groups 3 and 4- Total 19 animals.)*
TABLE
Basal
15 Mins. 30 Mins. 45 Mins. After After After Glucose Glucose Glucose
43.4 ±5.5 300. 4 ±11.9 3.2 ±0.6 147.8 ±6.6 100.2 ±6.0 95. 3 ±23.6 45. 7 ±12.6
45.6 ±5.5 301.5 ±10.4 3.0 ±0.8 136.5 ±10.5 90.2 ±7.1 491.2 ±230.9 42.1 ±17.2
45.2 ±6.0 296. 7 ±10.8 3.3 ±0.6 136.1 ±7.3 93.2 ±13.4 408.4 ±206.1 38. 4 ±11.2
46.5 ±6.0 294.3 ±11.0 3.4 ±0.7 136.5 ±7.3 89.6 ±6.1 405.6 ±248.6 37.2 ±9.9
3. 7 ±2.8 4.5 ±3.4 1.8 ±1.8 18.8 ±21.2 0.5 ±0.5 0.9 ±1.0 51. 9 ±37.9 94. 8 ±44.3 89. 0 ±66.6
5.9 ±3.5 4.4 ±1.8 2.5 ±1.8 11.2 ±5.4 1.0 ±0.9 1. 6 ±1.5 32.4 ±16.5 56.4 ±33.4 183.8 ±92.7
3. 7 ±3.1 3.1 ±1. 7 1.6 ±1.5 8.0 ±6.9 0. 7 ±0.9 1.1 ±1.5 23.6 ±11.2 37.4 ±20.5 140.5 ±83.6
2. 6 ±2.6
Blood: Hematocrit (per cent) Osmolality (mosm./kg.) Potassium (meq./L) Sodium (meq./L) Chloride (meq./L) Glucose (mg./100 ml.) Urea (mg./100 ml.) Urine: Volume (ml./min.) Osmolar clearance (ml./min.) Free water clearance (ml./min.) Potassium clearance (ml./min.) Sodium clearance (ml./min.) Chloride clearance (ml./min.) Urea clearance (ml./ min.) Endogenous creatinine clearance (ml./min.) P AH clearance (ml./ min.)
* Values expressed are
mean and
2. 7 ±1. 7 1. 6 ±1.3 8.9 ±8.6 0.5 ±0.6 0. 7 ±1.0 21.1 ±10.4 40.1 ±33. 7 165.3 ±121. 8
± one standard deviation.
serum sodium and chloride levels. The venous hematocrit levels show a rise following the glucose load. Transient alterations are seen in osmolar, free water, potassium, sodium and chloride clearances. Renal plasma flow shows a sustained rise associated with a reduction in glomerular filtration rate (GFR) as measured by both the endogenous creatinine clearance and urea clearance. A concomitant fall in serum urea concentration was also noted. A remarkable feature of these sequential changes is the constancy of the serum osmolality, despite the measured hypertonicity of the infused glucose. Table 2 illustrates the results obtained in 3 baboons (group 2) in which 51 Cr labeled red cells were used to determine blood volume changes. The serum protein and cholesterol levels and the serum urea concentration show a definite drop indicating a dilution of these substances. A rise
462
ROHlVI AND ASSOCIATES
is noted in the femoral hematocrit but no alteration occurred in the MCHC. Thus no acute changes in red cell morphology or intracellular water content occur owing to the glucose infusion. In contrast both the red cell mass and plasma volume increased as reflected in the increase in total blood volume measured during this time. Therefore, other body erythrocyte stores must be acutely mobilized into the directly measurable circulating blood volume. The remaining renal and electrolyte alterations are TABLE
2. Blood volume studies in animals given glucose loads (group 2) * 30Mins. Mixing 60 120 180 Period Mins. Mins. Mins. of After After After Glucose Glucose Glucose Glucose Load --- --- --- - - --Basal
Blood: Hemoglobin (gm.
%) MCHC Total red blood cell mass (units) (cc/ kg.) Total plasma volume (units) (cc/ kg.) Total blood volume (cc/kg.) Hematocrit vols. % Osmolality mosm./kg. Potassium (meq./ L) Sodium (meq./L) Chloride (meq./L) Glucose (mg./100 ml.) Urea (mg./100 ml.) Urine: Volume (ml./min.)
Osmolar clearance (ml./min.) Free water clearance (ml./min.) Potassium clearance (ml./min.) Sodium clearance (ml./min.) Chloride clearance (ml./rnin.) Urea clearance (ml./min.) Creatinine clearance (ml./rnin.)
14.4 ±1.1 35.0 ±1.0 21.5 ±5.4
12.8 ±1.4 33.7 ±2.1
40.8 ±5.6
15.3 ±1.9 35.0 ±1.0 29.8 ±7.7
15.3 ±1.8 35.0 ±1.0
14.6 ±0.9 36.0 ±0.0
44.6 ±11.3
62.2 77.4 ±10.1 ±23.1 39.3 38.0 40.0 43.6 43.3 ±2.3 ±2.0 ±2.5 ±3.1 ±2.6 299.3 300.3 290.0 285. 7 286. 7 ±10.0 ±13.4 ±1.5 ±4.2 ±7.2 3.0 3.4 3.1 3.2 3.2 ±0.8 ±0.7 ±0.2 ±0.5 ±0.7 121.0 132.0 147. 7 132. 7 132. 7 ±2.5 ±8.l ±7.5 ±9.0 ±9.6 101.0 80.0 84.0 85. 7 83.0 ±4.5 ±7.0 ±7.0 ±5.7 ±4.4 131. 7 664.3 370.3 353.0 340.0 ±15.0 ±240.4 ±120.7 ±281.0 ±233. 7 52.3 42.0 45. 7 45.3 43.4 ±12.5 ±9.5 ±10.8 ±9.9 ±10.0 0.1 ±0.1 0.1 ±0.2 0.04 ±0.04 1.0 ±1.5 0.02 ±0.03 0.05 ±0.02
-
2.6 ±0.8 3.8 ±1.0 1.2 ±0.7 16.4 ±4.6 0.6 ±0.3 1.5 ±0.5 44.1 ±19.1 48.5 ±22.4
4.1 ±1.1 4.9 ±0.7 0.8 ±0.4 12.8 ±1.8 1.3 ±0.5 2.5 ±0,5 27.6 ±10.4 27.2 ±14.2
1.1 ±0.7 1.8 ±1.2 0.6 ±0.4 5.4 ±4.7 0.2 ±0.2 0.5 ±0.4 11.4 ±8.8 13.4 ±13.2
0,6 ±0.4 1.2 ±0.7 0.6 ±0.4 4.1 ±2.1 0.1 ±0.0 0.2 ±0.1 8.5 ±5.2 13.3 ±9.6
• Values expressed are mean and ± one standard deviation.
TABLE
3. Dose of glucose administered intravenou.sly to baboons Mean*
Group 1 Group 2 Group 5 Groups 1, 3 & 4
2.33 3.59 1.89 2.28
• Gm. per kg. body weight.
similar to those observed in the animals from group 1. The animal in group 3 was studied before and after adrenalectomy. Glucose loading on 3 consecutive preoperative days demonstrated no adaptive change in the blood and urine alterations in this animal. The adrenalectomy did not result in significant differences in these alterations when compared to the preoperative status. The animal in group 4 was handled in the same manner as the one from group 3, but was subjected to bilateral nephrectomy instead of adrenalectomy. In this animal the systemic electrolyte levels before and after nephrectomy were qualitatively and quantitatively similar, indicating that the kidneys may play but a minor role in the serum changes observed following intravenous glucose loading. This observation seems to confirm the theory that serum dilution is the major factor responsible for the fall in the serum sodium and chloride concentrations. The 2 animals in group 5 were followed for 8 hours after the glucose administration. As may be anticipated a gradual return of all parameters, including glucose, sodium and chloride, to basal levels was observed. In addition serial measurement of blood pH, pC02 and p02 before, during and up to 8 hours after the glucose infusion were all within normal limits. Systemic alkalosis or acidosis was therefore not associated with the aforementioned renal and serum electrolyte changes. Table 3 illustrates that despite the wide range in body size, the volumes of glucose (ml./kg. body weight) administered within each experimental group were comparable DISCUSSION
Seldin and Tarail performed similar experiments with glucose loading in dogs and obtained results which correspond to those herein described.1 They ascribed the profound fall in the serum sodium and chloride levels to plasma dilu-
INTRAVENOUS GLUCOSE lN BABOONS
tion resulting from the alteration in the distribution of body water between the intracellular and extracellular spaces. considered that the high osmolality of the glucose was responsible for this phenomenon. The infused glucose solution itself is, however, insufficient to cause the degree of plasma dilution observed and it seems more probable that a. redistribution of the intracellular water is responsible for the observed effects. Goldberger 2 and Hoffman' support the theory of intracellular water shift as a major cause of the electrolyte changes observed when the serum glucose level is suddenly increased as occurs in diabetic ketosis. Alternative or perhaps additional reasons for the alterations in the serum sodium and chloride levels may be 1) water loss because of diuresis and 2) a shift of electrolytes into the cells. These mechanisms may come into play in a teleological attempt to compensate for the sudden rise in plasma. osmolality caused by the glucose. Weisberg states that glucose does not move across cell membranes as easily as do electrolytes. 4 Hence, a constant osm.olality of the extracellular fluid is maintained mainly by redistribution of electrolytes between the various fluid compartments of the body. This occurs in azotemia and diabetic ketosis where large un-ionized particles tend to raise the osrnolality of the extracellular fluid. The data summarized m table l demonstrate that the serum osmolality show~ little alteration following the administration of glucose. This finding supports the theory of the constancy of osrnolality after glucose loading. The fall in the serum urea level is indicative of plasma dilution, but the unchanged serum potassium level is not in keeping with plasma dilution. Seldin and Tarail noted this anomaly in dogs and felt that it emphasizes the importance of the combined effects of cellular transfers, urinary excretion and sodium dilution on each plasma constituant. 1 In a comprehensive review Gauer and Henry describe how increases in serum electrolyte concentration and/or osmola.lity expand the blood volume which will bring about 2. diuresis. 5 The alterations in blood volume are reflected by increases in cardiac output, stroke volume and renal plasma flow. 5 In the present study (table l) Gauer . 0. H. and Henry, .J. P.: Circulatory basis of fluid volume control. Physiol. Rev., 43: 423, 195;:1.
4. Significance of mean values al basal level and following inlravenou.s aluco.sc wlminis .. /ration (T-tes;")
TAHU;
------------------
Degrees T-Value of Freedom
p -
Blood: Hema.tocrit Osmolality Sodium Chloride
Potassium Glucose Urine:
Volume per minute Osmolality clearance Free water clearance
Potassium clearance Sodium clearance Chloride clearance Ure a clearance Creatinine clearance P.AH clearance
-~--
0.13 0.2J .5. 34 6. 30 0. 97
46 46 •16
8. 96
46
2.182 0. 080
3fi
Yes
33 33
None None
1. 057
1. 533 2.407 I. 732 1. 905 3. 901 1. 893
46
<0.45 <0.45 <0. 0005 <0. 0005 <0.2/J <0. 0005
•J6
<0.025 <0. •175 <0.15 :34 <0.l 36 <0.0125 :36 <0.05 31 <0.05 35 <0. 0005 18 <0.05 --------
None None
Highly Highly None Highly
.None Yes J:~{~S
Ye8 JligJ,ly Yes
5. Correla.lion of gl1.tcose and socl-ium and of glucose and chloride, i'Jefore ancl after inlravenou.s aclminislralion of glucose (product-moment correlation co~fficienl)
T,1.Bu;
Degrees
T-Value
of Free-
r
dom Before administration of glucose: Sodium: Glucose Chloride:Glucose After administration of glucose: S0di11m:Glucose Chloride:Glucose
0.13:0.291 0. 08:0.188
2,1
<0.40 <0.45
None,
24
0.66:25, 75 0.58:19.19
24 24
<0.001 <0.001
Yes Yes
None
----·--··-·
increases in Cp AH and renal plasma fl.ow were ob .. served. However, the GFR measured by 2 different methods demonstrated a. consistent fall a.fter the acute glucose loads despite the rise in From this observation it must he concluded i.haJ redistribution of blood flow within the must take place. The associated rise in electrolyte clearances seems to indicate tha.t a. occurs in the counter-current handling of saHs by the vasa-recta or, alternatively, by a decrease in proximal tubular sodium tion. In this series all the baboons had and polyuria following the intravenous infusion, indicating an osmotic diuresis. The spleen is not large in the baboon a.nd not the source of the increased red cell ma.s,.
464
ROHM AND ASSOCIATES
noted after glucose infusion. This phenomenon is at first perplexing, although Williams and Rodbard and Reeve and associates have shown that red cells can be sequestrated in the viscera of chickens and of splenectomized dogs and when returned to the circulation a rise in the hematocrit results. 6- 8 Murphy and associates found that the administration of dibenzyline produced a similar increase of total red cell mass. 9 It is also likely that in the baboon red cells are also sequestrated in visceral capillary beds. The expansion of the plasma volume by the administration of intravenous glucose brings about a mobilization of the sequestrated red cells. The rise of the hematocrit, total red blood cell volume and hemoglobin levels can, therefore, occur despite an expanding plasma volume. Student's T-tests were done on the results shown in table 4. The product-moment correlation coefficient tests are shown in table 5. It has already been indicated in the results and subsequent discussion that a statistically significant decrease in serum sodium and chloride concentrations occurs in response to glucose loads. This effect is purely dilutional and is unaltered by nephrectomy or adrenalectomy or by serially repeated infusions. Statistically significant renal circulatory changes can also be demonstrated. These changes are characterized by increased renal plasma flow, reduction in GFR and increased clearance of salt. This pattern of renal circulatory response indi6 Williams, F. L. and Rodbard, S.: Increased circulating plasma volume following phenoxybenzamine (dibenzyline). Amer. J. Physiol., 198: 169, 1960. 7 Reeve, E. B., Gregersen, M. I., Allen, T. H. and Sear, H.: Distribution of cells and plasma in the normal and splenectomized dog and its influence on blood volume estimates with P32 and T-1824. Amer. J. Physiol., 175: 195, 1953. 8 Reeve, E. B., Gregersen, M. I., Allen, T. H., Sear, H. and Walcott, W.W.: Effects of alteration in blood volume and venous hematocrit in splenectomized dogs on estimates of total blood volume with P32 and T-1824. Amer. J. Physiol., 176: 204, 1953. 9 Murphy, G. P., Gagnon, J. A. and Ewald, R. A.: Renal and systemic hemodynamic effects of dibenzyline in normotension and hemorrhagic hypotension. Surgery, 67: 856, 1965.
cated that an acute glucose load produces a redistribution of total renal blood flow and an associated decrease in the reabsorption of sodium in the proximal tubule. The series of physiologic responses to glucose loads are therefore not dependent on simple dilutional effects. The increased turnover of red cell stores, taken in concert with the manifestations previously mentioned represent important systemic and renal compensatory reactions. A statistically significant interaction occurs between the serum sodium chloride and glucose levels (table 5) after even relatively small glucose infusions, when rapidly administered. The importance of these observations becomes apparent when clinical situations requiring prolonged or intermittent intravenous therapy are considered. They become even more important when acute alterations in the extracellular fluid volume occur or can be anticipated during cardio-pulmonary bypass procedures or other major operative procedures. SUMMARY
In a series of experiments designed to clarify the acute effects of varying doses of intravenous glucose, 24 baboons were tested with acute glucose loads. The results demonstrate that there is a profound decrease in the serum sodium and chloride levels. These effects result from directly measurable increases in the blood volume caused by mobilization of erythrocytes from visceral capillary beds and from a shift of fluid from the intracellular to the extracellular compartments. The result is an expansion and dilution of the intravascular volume. The decreases in the sodium and chloride levels are aggravated by an associated saline diuresis. The latter effect is brought about by a rise in the renal plasma flow and decrease in the GFR as well as a reduction in tubular sodium reabsorption. This pattern of responses is unaltered by adrenalectomy or by repeated infusions. The systemic effects are not abolished by bilateral nephrectomy.
THE JOURNAL OF UROLOGY
Copyright © 1969 by The Williams & Wilkins Co.
RENAL AND SYSTEMIC, CIRCULATORY AND METABOLIC ALTERATIONS AFTER INTRAVENOUS GLUCOSE LOADS IN BABOONS G. F. ROHM, C. P. RETIEF, G. s. JOHNSTON, J. A. VAN ZYL, J. J. w. VAN ZYL, J. N. DEKLERK AND G. P. MURPHY* From the Family of lvI eclicine, University of Stellenbosch, Karl Breiner H Ospital, Bellville, South Africa; the Radioisotope Service, Waller Reecl General Hospital, Washington, D. C. and the Regional Kidney Center, Roswell Park Memorial Institute, Buffalo, New York
Renal function studies were performed with intravenous glucose loads to facilitate diuresis in a renal allotransplantation project jointly undertaken by the University of Stellenbosch and the Johns Hopkins Hospital. Glucose given by intravenous infusion over a short period can produce marked alterations in systemic and renal circulatory and electrolyte metabolism. This effect has been partially described in other species1 and until now the accepted explanation has been that the glucose infusion induces a sudden increase in plasma osmolality. The consequent shift of water from the intracellular to the extracellular fluid compartment was thought to result in an increase in plasma volume. The observed reductions in plasma sodium and chloride levels were attributed to the dilution which occurs. In addition, owing to the osmotic effect of the resulting glucosuria and the increased plasma volume, a diuresis occurs which can result in further salt loss. This phenomenon may have clinical significance. It has been observed that patients in a state of diabetic hyperglycemia, azotemia or patients in whom glucose or other osmotically active particles have been acutely administered1- 4 respond in an apparently similar manner. Accepted for publication March 4, 1968. This study was supported by the Council for Scientific and Industrial Research, the Cape Provincial Administration, the University of Stellenbosch, and private donations from the Brady Urological Institute, Johns Hopkins Hospital and from the Baxter Laboratories, JVIorton Grove, Illinois. * Reprint Requests: 666 Elm Street, Buffalo, New York 14203. 1 Seldin, D. W. and Tarail, R.: Effect of hypertonic solutions on metabolism and excretion of electrolytes. Amer. J. Physiol., 159: 160, 1949. 2 Goldberger, E.: A Primer of Water, Electrolyte and Acid-Base Syndromes. Philadelphia: Lea & Febiger, 3rd ed., 1965. 3 Hoffman, W. S.: The Biochemistry of Clinical Medicine. Chicago: The Year Book Medical Publishers, 3rd ed., 1964. 4 Weisberg, H. F.: Pitfalls in fluid and electrolyte therapy. Yena,, 1: 107, 1964.
The series of experiments reported herein were performed on baboons which were either intact or had been subjected to adrenalectomy or bilateral nephrectomy. The object was to determine the precise cause of the sequential electrolyte shifts which occur after the administration of glucose loads and to relate these shifts to the observed alterations in renal and systemic hemodynamics. MATERIALS AND METHODS
Twenty-four healthy, adult male and female baboons (Papio ursinus or Chacma baboon) weighing 8.1 to 28.7 kg., were divided into 5 experimental groups. The baboons were given phencyclidine hydrochloridet (1 mg./kg.) and a urethral catheter was inserted. During an observation period each animal received an intravenous infusion of 700 ml. 5 per cent glucose in water (35 gm.). Blood specimens were taken by femoral or peripheral vein puncture. Group 1 (17 animals): After obtaining basal blood and urine specimens within 10 to 20 minutes, the intravenous glucose infusion was given over a period of 45 minutes. Three further blood and urine samples were taken at 15-minute intervals. Group 2 (3 animals): In addition to the samples drawn as described in group 1, 10 ml. heparinized femoral vein blood was obtained and centrifuged. The erythrocytes from each animal were labeled with 10 to 30 µc 51 chromiurn (51 Cr). Free or excess 51 Cr was removed by repeated washing, and the labeled red cells were again suspended in the plasma obtained on centrifugation. This sample was then injected intravenously and after a 20-minute mixing period, 5 ml. venous blood was withdrawn and the red cell mass, plasma and total blood volumes were calculated using a well counter.t Sixty minutes after infusion of the
460
t Sernylan, Parke Davis, Co., Detroit, Michigan. t Picker well counter, donated by S. A. Atomic Energy Board.
461
INTRAVENOUS GLUCOSE IN BABOONS
initial glucose load was completed, these estimations were repeated. Hemoglobin concentration and mean cell hemoglobin concentration (MCHC) were recorded. Urine samples were collected before and for a 2;!,'i-hour period after the glucose infusion. Group 3 (1 animal) : This animal was studied for 3 consecutive days with repeated intravenous glucose loads similar to those given the animals in group 1. On the fourth morning a bilateral adrenalectomy was done. On that day and for 2 additional days the studies were repeated. Group 4 (1 animal): This animal was initially subjected to tests similar to those used on the animals in group 1. On the following day bilateral nephrectomy was performed and on 2 subsequent days the same studies were repeated, except for the urine collections. Group 5 (2 animals): The studies described for group 1 were again carried out, except hourly blood and urine samples were collected up to 8 hours after the infusion. In all groups except group 4, blood serum and urine specimens were obtained for clearance of para-aminohippuric acid (CPAH), endogenous creatinine clearance (CcR), osmolar clearance (CosM) and free water clearance. Sodium, chloride, potassium, protein, glucose, urea and cholesterol levels were also determined. To minimize the blood losB resulting from the many samples withdrawn, micro-chemical methods of determination were used. On an average 8 ml. blood was withdrawn for each sample. PAH levels were maintained by the infusion of 5 per cent glucose in water at a rate of 3 ml. per minute. Renal plasma flows were calculated with the usual correction for hematocrit. Determination of blood gases p02, pC02 and pH were performed in some instances. All data were statistically evaluated with the aid of a desk top computer.* The principles and practices of the South African Animal Welfare Society and American National Society for Medical Research were observed throughout these experiments. RESULTS
Table 1 shows the changes that occur in the blood and urine of baboons after a high dose of intravenous glucose over a short period. An osmotic diuresis is associated with a fall in * Olivetti Programma Town, South Africa.
101 computer,
Cape
1. Renal and systemic alterations after intravenous glucose loads in intact baboons. (Group 1 and preoperative groups 3 and 4- Total 19 animals.)*
TABLE
Basal
15 Mins. 30 Mins. 45 Mins. After After After Glucose Glucose Glucose
43.4 ±5.5 300. 4 ±11.9 3.2 ±0.6 147.8 ±6.6 100.2 ±6.0 95. 3 ±23.6 45. 7 ±12.6
45.6 ±5.5 301.5 ±10.4 3.0 ±0.8 136.5 ±10.5 90.2 ±7.1 491.2 ±230.9 42.1 ±17.2
45.2 ±6.0 296. 7 ±10.8 3.3 ±0.6 136.1 ±7.3 93.2 ±13.4 408.4 ±206.1 38. 4 ±11.2
46.5 ±6.0 294.3 ±11.0 3.4 ±0.7 136.5 ±7.3 89.6 ±6.1 405.6 ±248.6 37.2 ±9.9
3. 7 ±2.8 4.5 ±3.4 1.8 ±1.8 18.8 ±21.2 0.5 ±0.5 0.9 ±1.0 51. 9 ±37.9 94. 8 ±44.3 89. 0 ±66.6
5.9 ±3.5 4.4 ±1.8 2.5 ±1.8 11.2 ±5.4 1.0 ±0.9 1. 6 ±1.5 32.4 ±16.5 56.4 ±33.4 183.8 ±92.7
3. 7 ±3.1 3.1 ±1. 7 1.6 ±1.5 8.0 ±6.9 0. 7 ±0.9 1.1 ±1.5 23.6 ±11.2 37.4 ±20.5 140.5 ±83.6
2. 6 ±2.6
Blood: Hematocrit (per cent) Osmolality (mosm./kg.) Potassium (meq./L) Sodium (meq./L) Chloride (meq./L) Glucose (mg./100 ml.) Urea (mg./100 ml.) Urine: Volume (ml./min.) Osmolar clearance (ml./min.) Free water clearance (ml./min.) Potassium clearance (ml./min.) Sodium clearance (ml./min.) Chloride clearance (ml./min.) Urea clearance (ml./ min.) Endogenous creatinine clearance (ml./min.) P AH clearance (ml./ min.)
* Values expressed are
mean and
2. 7 ±1. 7 1. 6 ±1.3 8.9 ±8.6 0.5 ±0.6 0. 7 ±1.0 21.1 ±10.4 40.1 ±33. 7 165.3 ±121. 8
± one standard deviation.
serum sodium and chloride levels. The venous hematocrit levels show a rise following the glucose load. Transient alterations are seen in osmolar, free water, potassium, sodium and chloride clearances. Renal plasma flow shows a sustained rise associated with a reduction in glomerular filtration rate (GFR) as measured by both the endogenous creatinine clearance and urea clearance. A concomitant fall in serum urea concentration was also noted. A remarkable feature of these sequential changes is the constancy of the serum osmolality, despite the measured hypertonicity of the infused glucose. Table 2 illustrates the results obtained in 3 baboons (group 2) in which 51 Cr labeled red cells were used to determine blood volume changes. The serum protein and cholesterol levels and the serum urea concentration show a definite drop indicating a dilution of these substances. A rise
462
ROHlVI AND ASSOCIATES
is noted in the femoral hematocrit but no alteration occurred in the MCHC. Thus no acute changes in red cell morphology or intracellular water content occur owing to the glucose infusion. In contrast both the red cell mass and plasma volume increased as reflected in the increase in total blood volume measured during this time. Therefore, other body erythrocyte stores must be acutely mobilized into the directly measurable circulating blood volume. The remaining renal and electrolyte alterations are TABLE
2. Blood volume studies in animals given glucose loads (group 2) * 30Mins. Mixing 60 120 180 Period Mins. Mins. Mins. of After After After Glucose Glucose Glucose Glucose Load --- --- --- - - --Basal
Blood: Hemoglobin (gm.
%) MCHC Total red blood cell mass (units) (cc/ kg.) Total plasma volume (units) (cc/ kg.) Total blood volume (cc/kg.) Hematocrit vols. % Osmolality mosm./kg. Potassium (meq./ L) Sodium (meq./L) Chloride (meq./L) Glucose (mg./100 ml.) Urea (mg./100 ml.) Urine: Volume (ml./min.)
Osmolar clearance (ml./min.) Free water clearance (ml./min.) Potassium clearance (ml./min.) Sodium clearance (ml./min.) Chloride clearance (ml./rnin.) Urea clearance (ml./min.) Creatinine clearance (ml./rnin.)
14.4 ±1.1 35.0 ±1.0 21.5 ±5.4
12.8 ±1.4 33.7 ±2.1
40.8 ±5.6
15.3 ±1.9 35.0 ±1.0 29.8 ±7.7
15.3 ±1.8 35.0 ±1.0
14.6 ±0.9 36.0 ±0.0
44.6 ±11.3
62.2 77.4 ±10.1 ±23.1 39.3 38.0 40.0 43.6 43.3 ±2.3 ±2.0 ±2.5 ±3.1 ±2.6 299.3 300.3 290.0 285. 7 286. 7 ±10.0 ±13.4 ±1.5 ±4.2 ±7.2 3.0 3.4 3.1 3.2 3.2 ±0.8 ±0.7 ±0.2 ±0.5 ±0.7 121.0 132.0 147. 7 132. 7 132. 7 ±2.5 ±8.l ±7.5 ±9.0 ±9.6 101.0 80.0 84.0 85. 7 83.0 ±4.5 ±7.0 ±7.0 ±5.7 ±4.4 131. 7 664.3 370.3 353.0 340.0 ±15.0 ±240.4 ±120.7 ±281.0 ±233. 7 52.3 42.0 45. 7 45.3 43.4 ±12.5 ±9.5 ±10.8 ±9.9 ±10.0 0.1 ±0.1 0.1 ±0.2 0.04 ±0.04 1.0 ±1.5 0.02 ±0.03 0.05 ±0.02
-
2.6 ±0.8 3.8 ±1.0 1.2 ±0.7 16.4 ±4.6 0.6 ±0.3 1.5 ±0.5 44.1 ±19.1 48.5 ±22.4
4.1 ±1.1 4.9 ±0.7 0.8 ±0.4 12.8 ±1.8 1.3 ±0.5 2.5 ±0,5 27.6 ±10.4 27.2 ±14.2
1.1 ±0.7 1.8 ±1.2 0.6 ±0.4 5.4 ±4.7 0.2 ±0.2 0.5 ±0.4 11.4 ±8.8 13.4 ±13.2
0,6 ±0.4 1.2 ±0.7 0.6 ±0.4 4.1 ±2.1 0.1 ±0.0 0.2 ±0.1 8.5 ±5.2 13.3 ±9.6
• Values expressed are mean and ± one standard deviation.
TABLE
3. Dose of glucose administered intravenou.sly to baboons Mean*
Group 1 Group 2 Group 5 Groups 1, 3 & 4
2.33 3.59 1.89 2.28
• Gm. per kg. body weight.
similar to those observed in the animals from group 1. The animal in group 3 was studied before and after adrenalectomy. Glucose loading on 3 consecutive preoperative days demonstrated no adaptive change in the blood and urine alterations in this animal. The adrenalectomy did not result in significant differences in these alterations when compared to the preoperative status. The animal in group 4 was handled in the same manner as the one from group 3, but was subjected to bilateral nephrectomy instead of adrenalectomy. In this animal the systemic electrolyte levels before and after nephrectomy were qualitatively and quantitatively similar, indicating that the kidneys may play but a minor role in the serum changes observed following intravenous glucose loading. This observation seems to confirm the theory that serum dilution is the major factor responsible for the fall in the serum sodium and chloride concentrations. The 2 animals in group 5 were followed for 8 hours after the glucose administration. As may be anticipated a gradual return of all parameters, including glucose, sodium and chloride, to basal levels was observed. In addition serial measurement of blood pH, pC02 and p02 before, during and up to 8 hours after the glucose infusion were all within normal limits. Systemic alkalosis or acidosis was therefore not associated with the aforementioned renal and serum electrolyte changes. Table 3 illustrates that despite the wide range in body size, the volumes of glucose (ml./kg. body weight) administered within each experimental group were comparable DISCUSSION
Seldin and Tarail performed similar experiments with glucose loading in dogs and obtained results which correspond to those herein described.1 They ascribed the profound fall in the serum sodium and chloride levels to plasma dilu-
INTRAVENOUS GLUCOSE lN BABOONS
tion resulting from the alteration in the distribution of body water between the intracellular and extracellular spaces. considered that the high osmolality of the glucose was responsible for this phenomenon. The infused glucose solution itself is, however, insufficient to cause the degree of plasma dilution observed and it seems more probable that a. redistribution of the intracellular water is responsible for the observed effects. Goldberger 2 and Hoffman' support the theory of intracellular water shift as a major cause of the electrolyte changes observed when the serum glucose level is suddenly increased as occurs in diabetic ketosis. Alternative or perhaps additional reasons for the alterations in the serum sodium and chloride levels may be 1) water loss because of diuresis and 2) a shift of electrolytes into the cells. These mechanisms may come into play in a teleological attempt to compensate for the sudden rise in plasma. osmolality caused by the glucose. Weisberg states that glucose does not move across cell membranes as easily as do electrolytes. 4 Hence, a constant osm.olality of the extracellular fluid is maintained mainly by redistribution of electrolytes between the various fluid compartments of the body. This occurs in azotemia and diabetic ketosis where large un-ionized particles tend to raise the osrnolality of the extracellular fluid. The data summarized m table l demonstrate that the serum osmolality show~ little alteration following the administration of glucose. This finding supports the theory of the constancy of osrnolality after glucose loading. The fall in the serum urea level is indicative of plasma dilution, but the unchanged serum potassium level is not in keeping with plasma dilution. Seldin and Tarail noted this anomaly in dogs and felt that it emphasizes the importance of the combined effects of cellular transfers, urinary excretion and sodium dilution on each plasma constituant. 1 In a comprehensive review Gauer and Henry describe how increases in serum electrolyte concentration and/or osmola.lity expand the blood volume which will bring about 2. diuresis. 5 The alterations in blood volume are reflected by increases in cardiac output, stroke volume and renal plasma flow. 5 In the present study (table l) Gauer . 0. H. and Henry, .J. P.: Circulatory basis of fluid volume control. Physiol. Rev., 43: 423, 195;:1.
4. Significance of mean values al basal level and following inlravenou.s aluco.sc wlminis .. /ration (T-tes;")
TAHU;
------------------
Degrees T-Value of Freedom
p -
Blood: Hema.tocrit Osmolality Sodium Chloride
Potassium Glucose Urine:
Volume per minute Osmolality clearance Free water clearance
Potassium clearance Sodium clearance Chloride clearance Ure a clearance Creatinine clearance P.AH clearance
-~--
0.13 0.2J .5. 34 6. 30 0. 97
46 46 •16
8. 96
46
2.182 0. 080
3fi
Yes
33 33
None None
1. 057
1. 533 2.407 I. 732 1. 905 3. 901 1. 893
46
<0.45 <0.45 <0. 0005 <0. 0005 <0.2/J <0. 0005
•J6
<0.025 <0. •175 <0.15 :34 <0.l 36 <0.0125 :36 <0.05 31 <0.05 35 <0. 0005 18 <0.05 --------
None None
Highly Highly None Highly
.None Yes J:~{~S
Ye8 JligJ,ly Yes
5. Correla.lion of gl1.tcose and socl-ium and of glucose and chloride, i'Jefore ancl after inlravenou.s aclminislralion of glucose (product-moment correlation co~fficienl)
T,1.Bu;
Degrees
T-Value
of Free-
r
dom Before administration of glucose: Sodium: Glucose Chloride:Glucose After administration of glucose: S0di11m:Glucose Chloride:Glucose
0.13:0.291 0. 08:0.188
2,1
<0.40 <0.45
None,
24
0.66:25, 75 0.58:19.19
24 24
<0.001 <0.001
Yes Yes
None
----·--··-·
increases in Cp AH and renal plasma fl.ow were ob .. served. However, the GFR measured by 2 different methods demonstrated a. consistent fall a.fter the acute glucose loads despite the rise in From this observation it must he concluded i.haJ redistribution of blood flow within the must take place. The associated rise in electrolyte clearances seems to indicate tha.t a. occurs in the counter-current handling of saHs by the vasa-recta or, alternatively, by a decrease in proximal tubular sodium tion. In this series all the baboons had and polyuria following the intravenous infusion, indicating an osmotic diuresis. The spleen is not large in the baboon a.nd not the source of the increased red cell ma.s,.
464
ROHM AND ASSOCIATES
noted after glucose infusion. This phenomenon is at first perplexing, although Williams and Rodbard and Reeve and associates have shown that red cells can be sequestrated in the viscera of chickens and of splenectomized dogs and when returned to the circulation a rise in the hematocrit results. 6- 8 Murphy and associates found that the administration of dibenzyline produced a similar increase of total red cell mass. 9 It is also likely that in the baboon red cells are also sequestrated in visceral capillary beds. The expansion of the plasma volume by the administration of intravenous glucose brings about a mobilization of the sequestrated red cells. The rise of the hematocrit, total red blood cell volume and hemoglobin levels can, therefore, occur despite an expanding plasma volume. Student's T-tests were done on the results shown in table 4. The product-moment correlation coefficient tests are shown in table 5. It has already been indicated in the results and subsequent discussion that a statistically significant decrease in serum sodium and chloride concentrations occurs in response to glucose loads. This effect is purely dilutional and is unaltered by nephrectomy or adrenalectomy or by serially repeated infusions. Statistically significant renal circulatory changes can also be demonstrated. These changes are characterized by increased renal plasma flow, reduction in GFR and increased clearance of salt. This pattern of renal circulatory response indi6 Williams, F. L. and Rodbard, S.: Increased circulating plasma volume following phenoxybenzamine (dibenzyline). Amer. J. Physiol., 198: 169, 1960. 7 Reeve, E. B., Gregersen, M. I., Allen, T. H. and Sear, H.: Distribution of cells and plasma in the normal and splenectomized dog and its influence on blood volume estimates with P32 and T-1824. Amer. J. Physiol., 175: 195, 1953. 8 Reeve, E. B., Gregersen, M. I., Allen, T. H., Sear, H. and Walcott, W.W.: Effects of alteration in blood volume and venous hematocrit in splenectomized dogs on estimates of total blood volume with P32 and T-1824. Amer. J. Physiol., 176: 204, 1953. 9 Murphy, G. P., Gagnon, J. A. and Ewald, R. A.: Renal and systemic hemodynamic effects of dibenzyline in normotension and hemorrhagic hypotension. Surgery, 67: 856, 1965.
cated that an acute glucose load produces a redistribution of total renal blood flow and an associated decrease in the reabsorption of sodium in the proximal tubule. The series of physiologic responses to glucose loads are therefore not dependent on simple dilutional effects. The increased turnover of red cell stores, taken in concert with the manifestations previously mentioned represent important systemic and renal compensatory reactions. A statistically significant interaction occurs between the serum sodium chloride and glucose levels (table 5) after even relatively small glucose infusions, when rapidly administered. The importance of these observations becomes apparent when clinical situations requiring prolonged or intermittent intravenous therapy are considered. They become even more important when acute alterations in the extracellular fluid volume occur or can be anticipated during cardio-pulmonary bypass procedures or other major operative procedures. SUMMARY
In a series of experiments designed to clarify the acute effects of varying doses of intravenous glucose, 24 baboons were tested with acute glucose loads. The results demonstrate that there is a profound decrease in the serum sodium and chloride levels. These effects result from directly measurable increases in the blood volume caused by mobilization of erythrocytes from visceral capillary beds and from a shift of fluid from the intracellular to the extracellular compartments. The result is an expansion and dilution of the intravascular volume. The decreases in the sodium and chloride levels are aggravated by an associated saline diuresis. The latter effect is brought about by a rise in the renal plasma flow and decrease in the GFR as well as a reduction in tubular sodium reabsorption. This pattern of responses is unaltered by adrenalectomy or by repeated infusions. The systemic effects are not abolished by bilateral nephrectomy.