The half-life of exogenous gastrin in the circulation

1. A method of gastrin bio-assay is described which can be used on as little as 30 ng synthetic human gastrin I at a minimum concentration of 2.5 ng/ml.2. Pentagastrin or synthetic human gastrin I added to cat plasma can be stored on ice or at 4 degrees C, for periods up to 27 hr without apparent loss of gastrin activity.3. Between 1(1/2) and 13 min after the rapid I.V. injection of pentagastrin in the anaesthetized cat and between 1(1/2) and 15 min after the injection of synthetic human gastrin I, there is a rapid reduction of the gastrin concentration in the arterial plasma. The data relating log(10) gastrin concentration in arterial plasma with time can be fitted by a single term.4. Studies in vitro show that over the periods of time involved in the in vivo studies, both pentagastrin and synthetic human gastrin I are stable in cat plasma at 37 degrees C in concentrations which occurred in the circulating plasma.5. The half-life of pentagastrin in the circulating arterial plasma of the anaesthetized cat is 1.50 min (S.E. +/- 0.08) and the half-life of synthetic human gastrin I is 2.65 min (S.E. +/- 0.09).     

Testosterone affects formalin-induced responses differently in male and female rats

To evaluate the role of testosterone in pain modulation, we subcutaneously injected male and female rats with testosterone propionate (TP, 5 mg/kg in oil) or oil for 6 days; on the seventh day, all rats were subjected to the formalin test (10%, 50 microl). Behaviours were recorded in an open field (60 min). At the end of the formalin test, the rats were anaesthetized to collect blood from the abdominal aorta. Among the formalin-induced responses, licking was higher in females than males and was decreased by TP in females; jerking and flexing were only slightly affected by treatment. TP increased testosterone plasma levels in both sexes. These results indicate a role of testosterone in modulating formalin-induced responses. The effects appear to be different in males and females.     

Aspects of bile secretion in the rabbit.

1. Bile secretion was studied in anaesthetized rabbits from whom hepatic bile was collected by cannulation of the common bile duct. 2. The flow and composition of bile formed by rabbits anaesthetized with urethane differed significantly from that formed by rabbits anaesthetized with pentobarbitone sodium. 3. The I.P. injection of a hypertonic solution of sucrose (3 M) decreased bile flow and produced changes in the ionic composition of bile and of plasma. 4. The infusion of sodium taurodeoxycholate (1-5-20 mumole/min I.V.) gave higher rates of bile flow than did equimolar infusions of sodium taurocholate, and unlike taurocholate, increased the bicarbonate concentration of bile. 5. Acetazolamide (10-100 mg/kg) increased the concentration of bicarbonate both in bile and in plasma, and had little effect on bile flow. 6. The infusion of bromsulphthalein (5 mg/kg I.V.) decreased the excretion of bicarbonate into bile, and was associated with the formation of a hypotonic bile. 7. The implications of these results in relation to the mechanisms of bile secretion are discussed.     

Factors modifying renal tubular bicarbonate reabsorption in the dog

1. Acute experiments were carried out on anaesthetized dogs during metabolic alkalosis produced by I.V. administration of NaHCO(3). Partial constriction of one ureter led to a significant rise in the HCO(3) (-) threshold, beyond the simultaneous value for the other kidney. The magnitude of the increase was not correlated with the reduction of glomerular filtration.2. Stop-flow analysis, following complete unilateral obstruction of urine flow, demonstrated proximal as well as distal tubular reabsorption of bicarbonate. At any given plasma P(co2) the detailed configuration of the concentration changes which developed depended on (a) the presence and concentration of mannitol, (b) the duration of urinary stasis, and (c) the plasma concentration of HCO(3) (-).3. If a solution containing 15% (w/v) mannitol was infused I.V., the HCO(3) (-) concentration in free flow urine was lower than in plasma, and it fell further during arrest of flow in the entire column of trapped fluid. If less mannitol was infused, or none at all, interruption of urine flow led to a striking increase of HCO(3) (-) concentration in the distal portion of the occluded column, and to a fall in the fluid arrested in the proximal segments.4. It was demonstrated that the HCO(3) (-) concentration attained after 2(1/2), 6, or 15 min of urinary stasis at any point in the trapped fluid column was due to the combined effects of water reabsorption and HCO(3) (-) reabsorption which proceeded independently, and with a different time course.5. If mannitol was administered the lowest urinary HCO(3) (-) concentration in the series moved progressively to a more distal location with increasing duration of urinary stasis. When HCO(3) (-) concentration peaks were present in distal fluid they were conspicuous only after short interruptions of urine flow; during extended stop-flow periods they became attenuated, or disappeared. If no mannitol was administered this did not occur.6. Provided the plasma level of HCO(3) (-) was sufficiently elevated, mannitol (15%, w/v) was administered, and the time available for reabsorption was lengthened by ureter obstruction, much larger concentration differences between plasma and trapped fluid developed than the largest that are ever found between the plasma and freely draining urine. The magnitude of the largest plasma-urine (P-U) concentration difference for HCO(3) (-) increased with intratubular ;contact time', and no limiting value was found.7. Potassium concentration in distal occluded fluid fell with prolonged duration of stasis. This was related to the slow and progressive diminution of distal HCO(3) (-) concentration. But if instead of bicarbonate a nonreabsorbable anion, such as phosphate, was the dominant distal anion, K(+) concentration in distal fractions remained high and rose further with time.     

The relationship of age, sex, and glomerular location to the development of spontaneous lesions in the canine kidney: analysis of a life-span study

It is well documented that the presence of spontaneous renal disease and renal dysfunction increases with age in many species of mammals. Such alterations in renal structure and function may significantly affect the interpretation of long-term toxicology studies. The purpose of the present study was to assess the temporal evolution of selected renal lesions (cysts, interstitial inflammation, interstitial fibrosis, and glomerulosclerosis) in laboratory Beagle dogs, an important animal model in chronic toxicology studies. We examined representative sections of the kidneys from 159 purpose-bred and laboratory housed Beagle dogs and analyzed the extent and distribution of spontaneous lesions using the World Health Organization classification system for renal lesions. All dogs examined had renal lesions of varying severities. In the youngest dogs (up to 2 years of age), the density and severity of lesions were minimal, but were more severe by middle age (defined as 3-7 years). The density and severity of interstitial fibrosis and inflammation progressed with advancing age (p < 0.0001 for both) in both sexes. The density of tubular cysts increased linearly with advancing age in females (p = 0.0006), but not in males (p = 0.49). The cortical distribution of glomeruli and advancing age of dogs were significantly related to the development of glomerulosclerosis. As age increased, the presence of glomerulosclerosis increased (p = 0.0008). These data indicate that the development of renal lesions is progressive over the lifetime of a genetically similar population of laboratory Beagle dogs maintained under optimal standard environmental conditions. This information may be useful in the interpretation of compound effects during chronic toxicology studies in the dog.     

Effects of sex and ovarian hormones on the initial renal sympathetic nerve activity response to myocardial infarction

The physiological mechanisms contributing to sex differences following myocardial infarction (MI) are poorly understood. Given the strong relationship between sympathetic nerve activity (SNA) and outcome, we hypothesized there may be a sex difference in SNA responses to MI. In anaesthetized, open-chest male, female and ovariectomized (OVX) female Wistar rats, mean arterial pressure, heart rate and renal SNA were recorded in response to ligation of the left coronary artery. In males, renal SNA increased by 30 ± 6% in the first minute of coronary occlusion (P < 0.05) and remained elevated at 18 ± 7% above baseline (P < 0.05) at 2 h following MI. In response to MI, ovary-intact females displayed no change in renal SNA, whereas OVX females displayed a significant increase, similar to that seen in the males (increases of 43 ± 11% at 1 min and 21 ± 7% at 2 h post-MI, P < 0.05 versus intact females). Arterial baroreflex control of renal SNA had a smaller range in females (ovary intact and OVX) than males; no changes in arterial baroreflex responses were observed 1 h post-MI in males or females. Denervating the arterial baroreceptors abolished the renal SNA response to MI in the males, whereas in ovary-intact females and OVX females the response was unaltered. These findings suggest that ovarian hormones are able to blunt the initial sympathetic activation post-MI in females and that the importance of the arterial baroreflex in mediating initial sympathetic activation post-MI is different between the sexes.     

Morphology of the lumbar spinal canal in normal adult Turks

Pathological changes can occur in the diameters of the lumbar spinal canal. Therefore, assessing the canal size an important diagnostic procedure. Two hundred plain anterioposterior radiographs of the lumbar spine were examined. The sample consisted of 100 males and 100 females. The transverse diameter of the bony spinal canal (interpedicular distance), which was measured as the minimum distance between the medial surfaces of the pedicles of a given vertebra, was measured. In addition, the transverse diameter of the vertebral body, which was measured as the minimum distance across the waist of the vertebra, was measured. The distances were measured to the nearest one tenth of a millimetere using a Vernier caliper. At all levels (L1 - L5) the transverse diameters of the lumbar spinal canal were approximately 1 - 1.5 mm higher in males than in females. The intersegmental differences increased proximodistally, in both sexes. The ratio of the transverse diameter canal to the width of the vertebra ranged from 0.55 to 0.60 mm in both sexes. The distribution of the different lumbar canal types were 47% A, 42% B, 11% C. Additionally, subtypes were determined and classified.     

Renal venous and urinary PGE2 output during intrarenal arachidonic acid infusion in dogs

Inferences about total renal (venous and urinary) PGE₂ output from determinations of urinary excretion rates (U_PGE2V) cannot be made unless the distribution of PGE₂ between renal venous plasma and urine is known. Therefore, in the present study on intact kidneys of anesthetized dogs both urinary excretion of PGE₂ and the renal venous output (the product of plasma flow and venous concentration of PGE₂) was determined during low and high rates of renal PGE₂ synthesis. PGE₂ was measured in urine and arterial and renal venous plasma by radioimmunoassay during the following conditions: (1) Hydropenia. In the control condition U_PGE2V averaged 0.041±0.012 pmol/g·min and varied between 4 and 70% of the total PGE₂ output. With infusion of arachidonic acid (AA, 160 μg/kg·min) into the renal artery total PGE₂ output increased from 0.18±0.03 to 3.23±0.51 pmol/g·min, whereas arterial concentrations of PGE₂ were unchanged. The urinary fraction still varied between 6 and 46% of total renal PGE₂ output. (2) High urine flows caused by mannitol, saline or saline and ethacrynic acid (ECA) infusion. These procedures did not stimulate total renal PGE₂ output and the urinary fraction varied between 4 and 49%. ECA combined with saline infusion increased the urinary fraction significantly to 34.7±4.0%. AA increased the total PGE₂ output as during hydropenia, but the urinary fraction fell to 13% in 13 dogs and was unchanged at about 8% in six dogs. On average the urinary fraction of total PGE₂ output was significantly lower than in hydropenia. Thus, the urinary fraction of total renal PGE₂ output is not constant, and urinary excretion of PGE₂ does not give reliable information about renal synthetic rates of prostaglandins.     

Serum iron, total iron-binding capacity, and percentage saturation in normal subjects

The serum iron was determined in 60 normal subjects (38 males and 22 females) with a mean age of 32.0 and 36.2 years respectively. The plasma total iron-binding capacity (TIBC) was also determined in 54 of these subjects (32 males and 22 females). Serum iron and TIBC determinations were performed between 8.45 am and 9.15 am.The mean serum iron concentration is 138.3 +/- 4.3 mug/100 ml (SD +/- 32.9 mug/100 ml), and the mean TIBC is 470.1 +/- 6.8 mug/100 ml (SD +/- 50.1 mug/100 ml); the mean plasma siderophilin saturation is 30.0%. The mean values for serum iron, TIBC, and siderophilin saturation are similar in both sexes. They are normally distributed, and there is no significant correlation of serum iron and TIBC with age in either males or females.     

Comparative pharmacokinetics and renal accumulation of the iodized contrast media: ioxitalamic acid, ioxaglic acid and iohexol in the rabbit

Male and female rabbits were given a I.V. bolus injection of a single 5 ml/kg dose of either ioxitalamic acid, ioxaglic acid or iohexol. Animals were killed 2 hours, 8 hours and 24 hours after the injection. One group of animals received a continuous I.V. infusion of contrast agent at a constant rate of 2.5 ml/kg/hour of four hours. Animals were killed 30 minutes after the end of the infusion. Plasma and tissue concentrations of contrast agents were assayed using an HPLC method. A pharmacokinetic study was performed after the I.V. bolus injection. This study shows that: 1) Plasma elimination half-lives were identical in males and in females as well as for all three products. This half life is about 45 minutes. The distribution volume was identical in male and females as well as for all three products and was comprised between 20% and 26% of body weight. 2) For all three contrast agents, the renal cortical concentrations are higher than in the medulla or the papilla at all the observation times. The renal cortical accumulation of contrast agents is persistent in comparison to plasma concentrations. 3) Ionic and lipophilic properties of contrast agents seem to play an important role on the renal accumulation pattern.     

The renal blood flow and the glomerular filtration rate of anaesthetized dogs during acute changes in plasma sodium concentration.

1. The effects of acute changes in plasma Na concentration (P(Na)) on renal blood flow (RBF) and glomerular filtration rate (GFR) were studied in anaesthetized greyhounds. Saline was infused at a constant rate (0.1 ml. kg(-1) min(-1)) either into a renal artery or into a systemic vein. Plasma Na concentration was altered by varying the Na concentration of the infused saline from 0.154 to 0.077, 0.616 or 1.232 M.2. Blood pressure (B.P.), packed cell volume (PCV), concentration of plasma solids (PS) and the plasma concentration of H(+) and K (P(K)) ions were measured but no attempt was made to contain their fluctuation.3. An infusion of hypertonic saline into a renal artery usually led to an ipsilateral increase in RBF for 5-15 min, followed by a progressive fall. Over-all, mean values of RBF fell with P(Na) throughout the range studied (120-190 m-mole l.(-1)). Glomerular filtration rate rose with P(Na) to reach maximal values at P(Na) levels of 140-160 m-mole l.(-1), but fell thereafter. The combined fall in RBF and GFR, without change in filtration fraction, at P(Na) values above 160 m-mole l.(-1) is consistent with an alteration in afferent arteriolar resistance. The fall in GFR despite a rise in RBF noted when P(Na) was reduced below 140 m-mole l.(-1) requires an additional explanation.4. Renal blood flow was independent of P(K); it was inversely related to [H(+)] and directly related to PS. Glomerular filtration rate was independent of PCV and P(K). It was also inversely related to [H(+)] and directly related to PS up to a value of 6 g 100 g(-1) plasma, after which the relationship was reversed. These results suggest that the renal vascular responses to acute changes in P(Na) may be mediated in part, at least, by concurrent change in PS and [H(+)].     

Sex-related differences in the degree of lipid peroxidation activation and resistance to cardiovascular damage induced by stress in rats

It is shown that during stress a rapid twofold increase of erythrocyte acid resistance in rats of both sexes was followed by a 1.5-fold decrease toward the 60th min in males and the 120th min in females. In males, in contrast to females, the level of malonic dialdehyde was raised not only during stress, but also 1 and 24 hours after its completion. Stress-induced dystrophic changes of cardiomyocytes were more marked in males. The area of myocardial damage in females was almost twice as small as in males. It is assumed that the better resistance of females to stress-induced cardiovascular damage may be due to increased efficacy of antioxidant mechanisms inhibiting lipid peroxidation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, No 4, pp. 354–357, April, 1995 Presented by K. V. Sudakov, Member of the Russian Academy of Medical Sciences     

The relationship between plasma vasopressin concentration and urinary excretion during left atrial distension in anaesthetized dogs

The relationship between the changes in plasma vasopressin (AVP) concentration and urinary concentration during left atrial distension has been examined in 12 anaesthetized dogs. Left atrial pressure was increased by 1.2 kPa for 30 min. Plasma AVP concentration (radioimmunoassay) was decreased 5 min after the start of atrial distension and was increased again 5 min after the end of distension. The average decrease was about 50% from a mean of 6.4±2.4 pg · ml^–1 (SE). Urine osmolality decreased more slowly reaching its lowest value in the first 10 min after removal of atrial distension. In contrast sodium excretion increased immediately upon atrial distension. Because of the difference in the time course of the changes in plasma AVP and urine osmolality, plasma AVP was compared with the urine osmolality in samples collected 15 min after the plasma samples. At any plasma AVP concentration there was a wide variation in urine osmolality between dogs, but in any one dog there was clear relationship between plasma AVP and urine osmolality. The results support the view that the diuretic response to left atrial distension is due, at least in part to decreases in plasma AVP concentration. They also show that a stimulus arising from increased left atrial pressure influences the relationship between plasma osmolality and plasma AVP concentration.     

Interaction of changes in the third ventricular CSF tonicity, central and systemic AVP concentrations and water intake

Arginine vasopressin (AVP) is assumed to be involved as a central transmitter or modulator in the control of autonomic functions including thirst. In conscious dogs AVP concentration in cerebrospinal fluid (CSF) from the anterior part of the third ventricle (A3V) was analysed before and after local elevation of CSF osmolality by intracerebroventricular (i.c.v.) infusion of 0.35 M NaCl and after i.c.v. AVP infusion at 46 and 138 fmol ml-1 for 10 min. In addition, the effects of these i.c.v. infusions on water intake, plasma AVP concentration and blood pressure were investigated. In euhydrated dogs 0.35 M NaCl i.c.v. did not alter AVP concentration in the CSF during the subsequent 2 h. In contrast, plasma AVP concentration had increased significantly from 3.4 +/- 0.3 (control) to 6.4 +/- 0.7 and 4.7 +/- 0.3 fmol ml-1, 4 and 16 min, respectively, after the hypertonic stimulus. Drinking was stimulated with an average water intake of 14.5 +/- 3.7 ml kg-1 body wt. However, AVP infusion into the A3V did not elicit water intake despite increases of AVP concentration in the A3V by factors up to 40 above control. The same animals responded with spontaneous drinking to 0.35 M NaCl i.c.v. administered 160 min after the end of AVP infusions. Exogenously administered AVP disappeared from the A3V with a time constant of 13.8 min. The results do not support the view that AVP in the A3V CSF per se stimulates drinking.     

Epidemiology of diabetes mellitus in Sweden. Results of the first year of a prospective study in the population age group 15-34 years

All newly diagnosed cases of diabetes mellitus aged 15-34 years in Sweden, where the population in this age interval is about 2.3 million, were registered on standardized forms. During 1983, the first year of the study, there were 311 males and 161 females, excluding 280 with gestational diabetes. The annual incidence of diabetes was 26.2 per 100,000 in males and 14.2 in females. The respective figures for type I were 18.5 and 10.1, and for type II 5.7 and 2.9. The incidence of type I diabetes was similar for the four age groups (15-19, 20-24, 25-29, 30-34 years), while for type II it was highest in the oldest group. Types I and II, but not the sexes, differed as regards the cumulative distribution curves of the maximum blood glucose concentration during the first two weeks after diagnosis. The present incidence of diabetes in Sweden is higher, particularly in males than the rates for similar age groups in Oslo (1925-64) and Denmark (1970-77).     

Renal response to captopril in conscious dogs pretreated with indomethacin

This study was designed to determine whether the prostaglandins mediate the renal effects of captopril in the conscious sodium-replete dog. In a group of control animals (n = 9), effective renal plasma flow (ERPF) increased from 185 +/- 15 to 230 +/- 12 ml/min and plasma renin activity (PRA) increased from 0.64 +/- 0.15 to 12.9 +/- 1.1 ng ANG I . ml-1 . h-1 after captopril (10 mg/kg bolus plus 10 micrograms . kg-1 . min-1 i.v.) administration. Glomerular filtration rate (GRF) and sodium excretion (UnaV) were also increased significantly following captopril treatment, whereas urine volume (V), potassium excretion (UkV), mean arterial pressure (MAP), and heart rate (HR) remained unchanged throughout the experiment. When the same dose of captopril was given to indomethacin-pretreated dogs (5 mg/kg bolus plus 2 micrograms . kg-1 . min-1 i.v.), ERPF increased from 170 +/- 8 to 265 +/- 18 ml/min and PRA increased from 1.2 +/- 0.4 to 14.6 +/- 3.0 ng ANG I . ml-1 . h-1 after the captopril, while UnaV, UkV, and V remained unchanged. These data demonstrate that the prostaglandins do not mediate the ability of captopril to increase PRA or effective renal plasma flow in this experimental model.     

Vasopressin in blood and third ventricle CSF of dogs in chronic experiments

A device for chronic implantation was developed that allowed sampling of cerebrospinal fluid (CSF) from the anterior part of the third cerebral ventricle (A3V) of dogs in repeated experiments for up to 4 mo. Osmolalities, electrolyte concentrations, and concentrations of arginine vasopressin (AVP) measured with a radioimmunoassay were determined in repeated experiments on the chronically prepared animals under conditions of normal hydration, both in the conscious state and during inhalation anesthesia. In conscious dogs, AVP concentrations in plasma and CSF were 3.3 +/- 0.4 and 21.8 +/- 2.5 pg X ml-1, respectively. During anesthesia without surgical interference, the AVP concentrations in plasma and CSF were increased twofold above the levels obtained in conscious dogs. During the time of observation (180 min) all measured parameters remained constant. The AVP concentrations in plasma and CSF samples collected during the surgical procedure of device implantation were about 10-fold higher than in the samples collected during the conscious state. Thus, in each experimental condition, AVP concentration in the CSF collected from the A3V was consistently higher than that in the simultaneously collected blood samples.     

Comparison of PGE2, 6-keto PGF1 alpha and renin release from dog kidneys

Several renal cell types synthesize prostaglandin E2 (PGE2) and prostacyclin (PGI2). To examine whether the release of these prostaglandins varies in proportion, prostaglandin synthesis was stimulated in anaesthetized dogs by renal arterial constriction, ureteral occlusion, intrarenal angiotensin II infusion and infusion of arachidonic acid, the precursor of PG synthesis. PGI2 was measured as its stable hydrolysed product, 6-keto PGF1 alpha. The two former procedures raised PGE2 release to 13 +/- 2 pmol min-1, 6-keto PGF1 alpha release to 5 +/- 2 pmol min-1 and renin release to 23 +/- 5 micrograms AI min-1. Angiotensin II infusion, reducing the renal blood flow by 30%, increased PGE2 and 6-keto PGF1 alpha release only half as much as ureteral and renal arterial constriction, and exerted no significant effect on renin release. By increasing the infusion rate of angiotensin II up to 10 times, the renal blood flow remained unaltered in four dogs and fell to 50% of control in two dogs, but PGE2 and 6-keto PGF1 alpha release did not increase further in any of the experiments. Arachidonic acid, infused at 40 and 160 micrograms kg-1 min-1, increased prostaglandin release in proportion to the infusion rate. At the highest infusion rate, PGE2 release averaged 166 +/- 37 pmol min-1 and 6-keto PGF1 alpha release 98 +/- 28 pmol min-1. All procedures increased PGE2 and 6-keto PGF1 alpha release in a fixed proportion of about 2.5:1, whereas renin release increased only during autoregulatory vasodilation.     

Chin-marking behavior in male and female New Zealand rabbits: onset, development, and activation by steroids.

Chin marking (chinning) frequency was determined daily in 25 male and 24 female New Zealand rabbits aged 31-150 days. Chinning appeared earlier in females (mean +/- SD = 41 +/- 16 days) than in males (47 +/- 13 days). Between days 30-50, females displayed chinning more frequently than males. Thereafter, chinning increased steadily in both sexes up to day 100. Chinning curves levelled on days 100 and 140 in males and females, respectively. Profile analysis of male and female chinning curves showed significant differences in their slopes and in their population means (p < 0.001). At 7 months of age (days 210-224), both sexes displayed adult chinning frequencies: mean of means +/- SD = 103 +/- 18 and 79 +/- 14 marks/10 min in males (n = 8) and females (n = 8), respectively. The administration of testosterone propionate (TP, 1 mg/day) or estradiol benzoate (EB, 1 microgram/day) to males and females, respectively, from days 31-50, stimulated higher chinning frequencies than those displayed by untreated animals. Results suggest that chinning frequency increases throughout development largely as a consequence of a concomitant increase in sex steroid secretion.     

Dopamine-induced dissociation between renal metabolic rate and sodium reabsorption.

The stimulatory effect of dopamine on renal energy metabolism and its relationship to changes in tubular sodium reabsorption and plasma concentration of free fatty acids (FFA) were examined in anesthetized dogs. Dopamine infused intravenously at 25 mug/kg body wt-min for 30-60 min increased renal oxygen consumption (Rvo2) by 28 +/- 3%; glomerular filtration rate rose from 37 +/- 3 to 40 +/- 2 ml/min without significant changes in sodium excretion. Plasma FFA increased about 6 times. Total-body metabolic rate increased to 152 +/- 7% and fell to 119 +/- 5% of control after normalizing plasma FFA by beta-pyridylcarbinol; Rvo2 remained unchanged. Cortical and outer medullary heat accumulation rated increased to 137 +/- 6 and 133 +/- 10% after 1 h and to 163 +/- 18 and 179 +/- 26% of control after 2 h of dopamine infusion without further changes in sodium reabsorption. Furosemide reduced cortical and outer medullary metabolic rates as much as in control experiments (14 +/- 8 and 69 +/- 7%, respectively). Hence, dopamine exerts a renal calorigenic effect which cannot be accounted for by increased sodium reabsorption or attributed to increased supply of FFA.