Excretion Rates Of Na Research Articles

Impact of magnesium sulfate therapy in improvement of renal functions in high fat diet-induced diabetic rats and their offspring

The role of magnesium sulfate (MgSO4) administration to prevent diabetic nephropathy (DN) by reducing insulin resistance (IR) and the relationship of this action with gender and the expression of NOX4 and ICAM1 genes in the parents and their offspring were studied. Males and females rat, and their pups were used. Type 2 diabetes induced by high-fat diet (HFD) administration and a low dose of streptozotocin. Animals were divided into the: non-treated diabetic (DC), the diabetic group received insulin (Ins), and the diabetic group received MgSO4. Two groups of parents received just a normal diet (NDC). Following each set of parents for 16 weeks and their pups for 4 months, while eating normally. We assessed the amount of water consumed, urine volume, and blood glucose level. The levels of glucose, albumin, and creatinine in the urine were also measured, as well as the amounts of sodium, albumin, and creatinine in the serum. Calculations were made for glomerular filtration rate (GFR) and the excretion rates of Na and glucose fractions (FE Na and FE G, respectively). The hyperinsulinemic-euglycemic clamp was done. NOX4 and ICAM1 gene expressions in the kidney were also measured. MgSO4 or insulin therapy decreased blood glucose, IR, and improved GFR, FE Na, and FE G in both parents and their offspring compared to D group. MgSO4 improved NOX4 and ICAM1 gene expressions in the parents and their offspring compared to D group. Our results indicated that MgSO4 could reduce blood glucose levels and insulin resistance, and it could improve kidney function.

Serum and urine electrolyte changes following ligation of a left segmental renal artery in dogs

Background and Aim: Ligation of renal artery has been reported to cause acute reduction of nephron population resulting in altered Na + and K + excretion pattern. However, no study has reported electrolyte balance following the ligation of a branch of left renal artery. Methods: Segmental ligation of left renal arterial branch was performed in 18 dogs. Changes in the excretion pattern of Na + and K + and the urine flow rate by the remnant kidney have been observed. Serum and urine samples were collected before and after the ligation at 30-minute intervals for a period of two hours, and Na + and K + concentrations were determined along with the flow rate of urine. Results: A considerable reduction in the urinary excretion rate of Na + and K + was observed in 30 minutes after the ligation. Subsequently, a gradual rise in the rate of excretion of Na + and K + towards pre-ligation values was observed by the end of 120 minutes. Statistically significant increase in K + concentration in urine was observed at the end of two hours ( P = 0.023). The serum analysis for both the electrolytes in all experiments showed no significant changes in concentrations. Conclusion: Findings of the present study suggest that ligation of an artery segment in the kidney though affects acute changes in K + , it does not affect the overall homeostasis of either water or electrolytes. The maintenance of homeostasis might be achieved through the improvement of function by the remnant kidney.

A hypokalaemic woman with nephrocalcinosis: rebirth of old knowledge

The coexistence of hypokalaemia and nephrocalcinosis poses a challenge in rapid diagnosis and appropriate management. We describe a 38-year-old woman who presented with thirst, intermittent carpopedal spasm, paresthaesia of both hands and progressive weakness of lower extremities for two years. She had a history of chronic hypokalaemia of unknown cause with intermittent potassium supplementation for 7-8 y and bilateral nephrocalcinosis notable for one year. She denied vomiting, diarrhoea or use of laxatives, alcohol or diuretics. Her blood pressure was normal. Laboratory investigations showed hypokalaemia (2.7 mmol/L) and metabolic alkalosis (HCO3(-) 32.6 mmol/L, pH 7.46). Two random urine samples both showed a consistently high urine K(+) excretion but with excretion rates of Na(+), Cl(-) and divalent cations which were high in one sample but not the other. Ingestion of furosemide 120 mg daily for body image for 7-8 y was uncovered. With furosemide cessation and potassium supplementation, her hypokalaemia with neuromuscular symptoms was corrected but nephrocalcinosis persisted. Surreptitious use of diuretics for various purposes should be kept in mind as an important cause of hypokalaemia and/or nephrocalcinosis. Measurement of electrolyte concentrations in at least two random urine samples is warranted to distinguish it from true renal tubular disorders and extrarenal causes.

Uptake, handling, and excretion of Na+ and Cl- from the diet in vivo in freshwater and seawater-acclimated killifish, Fundulus heteroclitus, an agastric teleost

A radiotracer approach using diets labelled with (22)Na(+), (36)Cl(-) and [(14)C]polyethylene-4000 (PEG-4000) was employed to investigate the role of intestinal uptake from the food in ion homeostasis in the killifish Fundulus heteroclitus. This euryhaline teleost lacks both a stomach and the capacity for Cl(-) uptake at the gills in freshwater. PEG-4000 appearance in the water was minimal up to 10-11 h post-feeding, indicating the virtual absence of Na(+) and Cl(-) loss in the faeces up until this time. Rapid uptake of dietary Na(+) and Cl(-) occurred and more than 88% of (22)Na(+) and (36)Cl(-) were absorbed in the intestine by 3 h post-feeding; excretion rates of Na(+) and Cl(-) originating from the food were greatest during this period. Uptake and excretion of Cl(-) from the diet was fivefold to sixfold greater than that of Na(+) in freshwater, and approximately threefold greater in seawater. Excretions of dietary Na(+) and Cl(-) by seawater-acclimated killifish were far greater than by freshwater-acclimated killifish in this time frame, reflecting the much greater branchial efflux rates and turnover rates of the internal exchangeable pools. At both 3 and 9 h post-feeding, the largest fraction of dietary Na(+) was found in the carcass of freshwater-acclimated fish, followed by the external water, and finally the digestive tract. However, in seawater-acclimated fish, more was excreted to the water, and less was retained in the carcass. For Cl(-), which was taken up and excreted more rapidly than Na(+), the majority of the dietary load had moved to the external water by 9 h in both freshwater and seawater animals. After 7 days training on a low-salt natural diet (live Lumbriculus variegatus worms; 31.5 μmol Na(+) g(-1) wet mass) versus a high-salt synthetic pellet diet (911 μmol Na(+) g(-1) dry food mass), freshwater killifish exhibited a lower absolute excretion rate of Na(+) from the low-salt diet, but relative uptake from the intestine and retention in the carcass were virtually identical from the two diets. Seawater killifish excreted relatively more Na(+) from the low-salt diet. Overall, our results emphasize the importance of dietary Na(+) and Cl(-) in the electrolyte economy of the killifish, particularly in freshwater, and especially for Cl(-).

Renal sympathetic nerves do not modulate renal responses to haemorrhage in conscious lambs.

The present study was designed to investigate the renal responses to hypotensive haemorrhage early in life and the role of renal sympathetic nerves in modulating these renal responses. To this end, experiments were carried out in conscious, chronically instrumented lambs with either intact renal nerves (n = 7, Intact) or bilateral renal denervation performed at the time of surgery (n = 5, Denervated). Parameters of renal function were measured before and after 20% haemorrhage (experiment 1) and 0% haemorrhage (experiment 2), the latter serving as a time control. The two experiments were performed in random order at intervals of 24-48 h. Within 20 min of hypotensive haemorrhage in intact lambs, glomerular filtration rate decreased by approximately 60%; this response was not altered by renal denervation. Since renal plasma flow remained constant after haemorrhage, the filtration fraction also decreased. After 20% haemorrhage, urinary flow rate decreased in intact lambs; this response was also not altered by renal denervation. Excretion rates of Na+ and K+ as well as urinary osmolality and free water clearance were not altered by haemorrhage in either intact or denervated lambs. These data provide the first description of renal responses to haemorrhage early in life. In addition, the present findings provide new information that renal responses to haemorrhage early in life do not appear to be modulated by renal sympathetic nerves.

Alteration of renal function of rats following spaceflight.

Following spaceflight, changes in renal function of humans have been suggested. To assess the effects of readaptation on renal function, urine was collected from male rats ( approximately 245 g) over a 2-wk period following a 14-day spaceflight. Rats were assigned to three groups: flight animals (n = 6), flight controls (n = 6) housed in the flight cages on the ground, and vivarium controls (n = 5) housed in standard shoe box cages. Animals were placed into individual metabolic cages for urine collection. Urine output was significantly increased for 3 days following flight. Excretion rates of Na+ and K+ were increased, resulting in an increased osmotic excretion rate. Creatinine excretion rate increased over the first two postflight days. Glomerular filtration rate increased immediately following spaceflight without changes in plasma creatinine, Na+, K+, or osmolality. Increased excretion of solute was thus the result of increased delivery and a decreased percent reabsorption of the filtered load. Osmolal clearance was increased immediately postflight while free water clearance was decreased. In growing rats, the diuresis after short-duration spaceflight is the result of an increase in solute excretion with an accompanying reduction in free water clearance.

Comparative effects of diuretics and atrial peptide in chronic caval dogs

Anesthetized chronic caval dogs with ascites were given atrial natriuretic peptide (ANF) at 75 ng.kg-1.min-1 iv and were characterized as to natriuretic response [n = 21; urinary excretion rate of Na (UNaV): 28-362 mu eq/min] or lack of response (n = 14; UNaV: 0-10 mu eq/min). Sixteen normal dogs showed an increment in UNaV between 38 and 288 mu eq/min following the same dose of ANF. Both caval "responders" and "nonresponders" were equivalent with regard to pre- and post-ANF hemodynamics and renal function. When various diuretic agents (glucagon, acetazolamide, furosemide, thiazide, amiloride) were administered, equivalent natriuretic responses were obtained between both groups of caval dogs and the controls. An acute saline load (7% body wt), however, produced a greater natriuresis in controls than in caval dogs, but in this latter group the response was similar in responders and nonresponders. When six caval dogs each were initially pretreated with either amiloride or ANF, and then treated with a second agent, an additive natriuretic effect was obtained. These results suggest that tubular resistance to diuretics in caval dogs is unique to ANF, and this peptide appears to act at an additional Na transport site separate from amiloride-inhibitable channels.

Effect of potassium depletion on renal tubular function in the rat.

1. In order to investigate the effects of K+ depletion on renal function, micropuncture studies were performed on anaesthetized rats which had been kept on a K+-deficient diet for 2 weeks; results were compared with those from control animals. 2. In the K+-depleted animals, values for total glomerular filtration rate and single-nephron filtration rate were significantly lower than in controls. Urine osmolality was also reduced; this was associated with reductions in the osmolality, Na+ concentration and K+ concentration of papillary interstitial fluid. No significant difference between urine and papillary osmolality was observed. 3. Fractional reabsorption by the proximal convoluted tubule was enhanced in the K+-depleted animals; end-proximal fluid delivery was markedly reduced. 4. Absolute, but not fractional, delivery of K+ to the beginning of the distal tubule was reduced in the K+-depleted animals. In contrast to observations in control rats, no net secretion of K+ into the distal tubule occurred and there was indirect evidence of K+ reabsorption in the collecting duct. 5. K+ depletion was associated with reductions in the delivery of Na+ and water to early and late regions of the distal tubule, whereas excretion rates of Na+ and water were unaffected. 6. It is suggested that the reduction in Na+ delivery to the loop of Henle (arising from the changes in filtration rate and proximal tubular reabsorption) might contribute to the reduced medullary osmotic concentration observed during K+ depletion. Reductions in fractional reabsorption of Na+ and water in the collecting duct might result from lowered plasma aldosterone levels and the reduced medullary osmolality.

Ontogeny of the renal response to natriuretic peptide in sheep

The ontogeny of the renal response to continuous systemic infusion of atrial natriuretic peptide (ANP) was studied in chronically instrumented fetal, newborn, and adult nonpregnant sheep. Plasma immunoreactive ANP (ANPir) concentrations during low (0.025 microgram.kg-1.min-1) and high rate (0.1 microgram.kg-1.min-1) ANP infusion were similar between each group of animals. Decrease in renal blood flow velocity (RBFV) and rise in renal vascular resistance (RVR) were observed in fetal and newborn lambs during ANP infusion. The percent changes in RBFV and RVR were of significantly (P less than 0.05) greater magnitude during high ANP infusion rate in fetuses (-28.5 +/- 8.5 and 93 +/- 6.4%) than in adult sheep (-6.6 +/- 3.2 and -4.4 +/- 4.9%). ANP produced no changes in urine flow (V) in fetuses but increased V significantly in newborn lambs and adult sheep. Glomerular filtration rate increased significantly during ANP infusion in adult sheep but not in fetal and newborn lambs. Percentage changes in urinary excretion rate of Na (UNaV) during high ANP infusion rate were significantly higher in adult sheep (3,520 +/- 2,414%) than in newborn (157 +/- 106%) and fetal lambs (198 +/- 84%). These results suggest that the cardiovascular, renal hemodynamic, and possibly renal function responses to continuous ANP infusion increase during maturation, the overall response being larger in adult animals.

Pharmacokinetic and pharmacodynamic studies of piretanide in rabbits. III. Sodium and potassium excretion under different hydrated conditions.

The diuretic effect of piretanide, one of the loop diuretics, was investigated in three different hydrated conditions, namely well hydrated condition (treatment I), progressive hydropenic condition (treatment II) and complete hydropenic condition (treatment III) in rabbits. Each rabbit received intravenous administration of 1.5 or 15 mg/kg of piretanide and the urine flow rate, the excretion rates of Na and K, plasma concentrations of Na and K, urine osmolarity, plasma concentration of piretanide and urinary excretion of piretanide were determined after administration. The pharmacokinetics of piretanide was not influenced by the hydration state of the body, even in treatment III. The diuretic effect of piretanide evaluated by both urine flow rate (EH2O) and Na+K excretion rate (ENa+K), was significantly affected by the hydration state of the body. The more the hydropenic state was developed, less amounts of urine or electrolytes were excreted. A pharmacokinetic-pharmacodynamic link model which was proposed in the previous paper was applied to the present experimental results. The result indicated that the diuretic effect, even in the complete hydropenic condition (treatment III), was reasonably described by the model, with minor modifications. The time course of the excretion rate of K (EK) was not always in parallel with ENa+K, but was dependent on treatments. We found that the K-fraction, which was known as an indicator of the Na-K exchange reaction in the distal tubule, was quantitatively related to ENa+K, using a simple equation. Accordingly, the time course of EK was also calculated. The result also indicated that time courses of EK were described reasonably well by the model, regardless of treatments and doses.

A quantitative method of evaluating the diuretic response to furosemide in rats.

Furosemide effects are usually evaluated by measuring the urinary excretion rate of Na+ (UVNa) in humans. In the present study, however, UVNa showed a nonlinear relationship with urine flow rate after intravenous injection of furosemide in rats. In contrast, when the urinary excretion rate of (Na+ + K+) (UVNa + K) was plotted against the urine flow rate, a linear regression line was observed, with small interindividual variations in normal rats and in rats with uranyl nitrate-induced acute renal failure (ARF). Piretanide, a loop diuretic, also showed a similar relationship, while other types of diuretics revealed different slope values for the relationship. Although the urinary excretion rate of Cl- (UVCl) vs UVNa + K is expected to show a linear relationship in normal rats, the correlation coefficient of the linear regression line was smaller than that of the urine flow rate vs UVNa + K. Further, the slope of UVCl vs UVNa + K was slightly different in ARF rats. Therefore, UVNa + K provides a better quantitative measure of diuretic response to loop diuretics than UVNa or UVCl.

Antidiuretic effect of [Sar1, Val5, Ala8] angiotensin II in Lophius americanus

AbstractWe have reported previously that angiotensin II increases urine flow and Na and K excretion rates in the aglomerular goosefish Lophius americanus. The present experiments were undertaken to determine if antagonism of endogenous angiotensin has the opposite renal effects. Arterial blood pressure, urine flow, and plasma and urine electrolytes were measured during two consecutive clearance periods in two groups of goosefish. The control group (n = 7) received saline intravenously during both periods; the experimental group (n = 8) received saline during the first period and a competitive antagonist of angiotensin II (saralasin, or [Sar1, Val5, Ala8] angiotension II) dissolved in saline during the second period. The control group exhibited no significant change over time in any of the measured variables: arterial blood pressure; plasma [Na], [K], [Mg], [Ca]; osmolality; urine flow; and excretion rates of Na, K, Ca, and Mg. Arterial blood pressure and plasma electrolytes and osmolality were stable over time in the experimental group also. However, during saralasin infusion there were significant decreases in urine flow and in excretion rates of K, Mg, and Ca. Taken together with our previous results, these observations suggest that endogenous levels of angiotensin in goosefish are sufficient to have direct renal effects. The mechanisms of action of angiotensin are not clear, but involve neither changes in systemic blood pressure nor filtration but might involve inhibitory effects of angiotensin on tubular reabsorptive processes.

Influence of temperature acclimation on renal hydromineral metabolism in smolts of Salmo salar L.

1. 1.|Rates of water, Mg, Cl, Na and K excretion through the kidneys, renal total and Na/K-activated ATPase activities, concentration of water in white muscle tissue and of electrolytes in blood plasma were measured in Atlantic salmon smolts. 2. 2.|The initial osmoregulatory responses were studied in salmon acclimated to 2 and 11°C. Effects of temperature change from 2 to 11°C were first measured in freshwater (FW). Effects of seawater (SW) and MgCl 2-enriched FW (MgFW) were then tested at 24 h at the common water temperature of 11°C. 3. 3.|In the 12–24 h following an increase of temperature in FW, partial or no compensation ( Q 10 1.6–2.5) of excretion rates was observed. After 20 days, however, an inverse compensation ( Q 10 5.7 and 5.4) in excretion of Mg and K had occurred. 4. 4.|Adaptation to cold did not affect the amount of water excreted by smolts in either SW or MgFW. The excretion rate of Cl both “cold”- and “warm”-acclimated fish was indifferent with respect to SW. 5. 5.|In SW and MgFW the excretion of Mg was lower in “colld”- than in “warm”-acclimated smolts. Correspondingly, excretion rates of Na and K in “cold” fish did not decrease as quickly with respect to saline waters as in “warm” fish. 6. 6.|Total ATPase activity of kidneys was 19% ( P < 0.05) higher in smolts acclimated to 11°C than to 2°C, but no such difference was observed in Na/K-ATPase. Following exposure to SW both ATPase activities were significantly decreased in “cold” but not in “warm” salmon. Levels of muscle water behaved similarly.

Separate renal function studies in conscious dogs with renovascular hypertension.

A new method was developed for separate kidney function studies by catheterizing the ureters and exteriorizing the catheters through the urethra into the vagina. Renal artery plication was performed to reduce blood flow to one kidney by 66 +/- 5%. Arterial pressure increased from 107 +/- 2 to 131 +/- 3 mmHg and remained elevated for 28 days. Plasma renin activity was increased for the first 7-10 days only. Sodium and water excretion were markedly reduced in the kidney with the stenosed renal artery and after the first 2 days Na and water excretion were incresed in the contralateral kidney. These changes in Na and water excretion were frequently associated with similar directional changes in glomerular filtration rate (GFR) and renal plasma flow. An exception was noted in that renal sodium and water excretion remained low throughout the 28 days in the kidney with the constricted renal artery, whereas GRF returned to near the control level by the end of 2 wk. Altered filtration fraction did not appear to be a determining factor in control of the rate of Na excretion. It is suggested that GFR, the renin-angiotensin-aldosterone system, and other as yet undefined factors are involved in salt and water homeostasis during unilateral renal artery stenosis with hypertension.

Acute compensatory adaptation of renal function following contralateral kidney exclusion in Brattleboro rats with diabetes insipidus.

1. The function of the remaining kidney following ligation of a single renal pedicle in anaesthetized rats with hereditary hypothalamic diabetes insipidus (DI) was studied using clearance methods. Values were compared with those obtained in DI rats which had been sham operated. 2. A small increase in the glomerular filtration rate of the remaining kidney was observed, which was statistically significant after 150 min. Increases in effective renal plasma flow were also observed, but these were not statistically significant. 3. The fractional excretion rates of Na and K increased immediately after contralateral kidney ligation; as a result total Na and K excretion rates remained similar to values in sham operated animals with both kidneys intact. 4. Fractional urine flow (V/GFR) increased by approximately 40% after contralateral ligation. It is argued that, since water reabsorption in the diluting segments of the nephron was unlikely to have been reduced, the increase in V/GFR was an indication that fractional fluid reabsorption in the proximal nephron had been inhibited. 5. Clearance determinations showed that the fractional reabsorption of Na in the proximal nephron was similarly reduced after contralateral ligation. However, Na reabsorption in the distal nephron increased, though not by enough to prevent a doubling of fractional sodium excretion. 6. The osmolalities of interstitial fluids obtained from the medulla and papilla of the contralateral kidney 2 hr after unilateral renal pedicle ligation were slightly, but significantly, higher than corresponding values in sham operated rats. This raises the possibility that salt reabsorption in the ascending limb of Henle might be enhanced immediately after contralateral renal exclusion.

Effect of intraventricular administration of noradrenaline on water diuresis in goats.

Duriing water diuresis in conscious goats, noradrenaline (NA), its antagonists phentolamine, phenoxybenzamine and propranolol and also atropine were administered into the 3rd ventricle. The subsequent effects on water diuresis and on the excretion rates of Na+, K+ and Cl- were investigated. Infusion of NA into the 3rd ventricle induced a strong and significant antidiuretic response and a decrease in the Na+ : K+ excretion ratio; these effects were dose-dependent. High doses of NA produced a significant increase in urinary K+ excretion. Similar results were observed after i.v. administration of arginine-vasopressin. Pretreatment with phentolamine injected into the 3rd ventricle produced a dose-dependent inhibition of the NA-induced antidiuretic effects. Phenoxybenzamine also blocked the response to NA but a dose-response relationship was not apparent. Atropine and propranolol did not block the response to NA.

尿生成の日内変動に関する研究

Twenty-six subjects were divided into two groups: enuretics, and patients with various diseases but without enuresis. These subjects were studied to investigate the diurnal variation of urinary volume and of urinary total solute, Na, K, 17-OHCS and ADH excretions in urine at 3 hourly intervals over periods one to nine days.The results are summarized as follows:I. Variation in urinary volume, total solute, Na, and K excretionA. Excretion of urinary volume and total soluteIn the subjects with nocturnal enuresis in contrast with other subjects under ten years of age, urinary volume and total solute excretions increased both at night and in the day. There was in particular an increase in the volume of night urine and the volume of solute excretion at night and there was a reduction in the volume of total solute of daytime urine.In the subjects in the 10-15 year age group, the enuretic group, as compared with other group, showed an increase in urinary volume and total solute excretions at night. And also the subjects above sixteen years of age showed a similar tendency.B. Excretion of total solute and Na in urine.It was noticed that the rate of Na excretion into total solute excretion was almost constant. In particular, a large relative excretion of total solute and Na in nighttime urine was observed in the groups under 10 years of age, in the 10-15 year group, and in the over 16 group.C. Excretion of total solute and K in urine.When the total solute increased, the volume of K in the total solute increased slightly but it could hardly be recognized that there was any fixed tendency in the rate of increase. Therefore, there was no significant difference between enuretics and other subjects.II. Daily variation of urinary 17-OHCS levelIn the group without enuresis under 10 years of age, the nocturnal values were the lowest, but the values increased rapidly in the early morning and decreased gradually in the afternoon. On the other hand, in the enuretic group, the urinary values were relatively low at night and increased slightly in the morning, but were low as a whole and the variation of them was only slight for all periods. Because measurements of the enuretic 10-15 year age group were infrequent, it was difficult to evaluate the difference between the enuretic group and the other group by the same criterion. But it would appear that the results for the subjects under 10 years of age were almost the same as those above.In the group without enuresis above sixteen, the nocturnal values were low and rose in the morning and fell slowly in the afternoon. But in the enuretic group, quite a wide distribution was observed for all periods of the day and night, and it was difficult to perceive any definite trend of daily variation.III. Diurnal variation of urinary ADH level in urine.In the group without enuresis under 10 years of age, the urinary values were relatively low in the early morning and rose slightly in the forenoon. These values were maintained in the afternoon but fell at night. On the other hand, although scattered from night to day, the enuretic group showed very similar changes as compared with the group without enuresis. Later, cases with extremely high and extremely low values were found.In the 10-15 year age group, it was difficult to evaluate the difference between the enuretic group and the group without enuresis, but in the enuretic group, it was observed that some enuretic subjects showed low values in the morning, and high values in the evening and at nighttime.But in early morning and in the evening, cases with high values among the non-enuresis group were found in the over 16 year group, but apart from this there was no particular difference between the two group during the daytime.

Kidney function during choline deficiency

The relationship between kidney damage and hypertension caused by choline deficiency was studied in young male rats. Excretion of a test load of NaCl solution was used as a test of kidney function and it was found that the proportion of Na+ of the test load excreted in 4 hours decreased significantly as choline deficiency progressed. K+ excretion was also depressed by about 15 per cent.Administration of ethyl trichloracetate or α methyl dopa reduced the hypertension in choline deficient rats, with increased rate of Na+ excretion with former treatment and decreased rate of excretion with the latter. Regimes of partial immersion in water had no effect in excretion rate of Na+ but reduced hypertension.Hemicholinium-3 raised blood pressure of choline supplemented rats to levels similar to that of deficient but had no effect either on blood pressure of deficient or Naf excretion in supplemented or deficient rats. Metaraminol inhibited Na+ excretion in both supplemented and deficient rats.

Effects of salt loading and haemodilution on the responses of perfused cat kidneys to angiotensin

1. Effects of single intra-arterial injections (0.1-1.0 mug) of angiotensin II have been observed on cat kidneys perfused with heparinized blood from heart-lung circuits.2. Angiotensin II always caused an abrupt decrease in renal plasma flow (R.P.F.) which reached maximum in 1-2 min and lasted over-all for only 3.5-4.0 min. Glomerular filtration rate (G.F.R.) usually and filtration fraction (F.F.) always increased.3. Angiotensin II caused antidiuresis provided that the kidney had not been subjected either to salt loading or to haemodilution within the preceding 3 hr. These pretreatments converted the antidiuretic action of angiotensin into a diuresis.4. Angiotensin II raised the rate of Na excretion, the urinary concentration of Na and the urinary Na/K whether anti-diuretic or diuretic.

Effect of a vapor barrier on rates of excretion of sweat solutes.

The effects of a vapor-impermeable barrier on rates of excretion of Na, Cl, K, true creatinine and ‘apparent’ creatinine from the arms of men during thermal sweating were determined by collecting sweat solutes simultaneously from both arms, one of which was enclosed in a polyethylene bag. The separate effects on rates of excretion of the higher local skin temperature (Ts) and relative humidity (RH) imposed by a vapor barrier were assessed by means of a thermoregulated arm-chamber. Wearing a vapor barrier resulted in a significantly decreased rate of excretion of K and an increased rate for both true and ‘apparent’ creatinine. The effect on ‘apparent’ creatinine was attributable entirely to the increased excretion of the fraction represented by true creatinine. Rates of excretion of Na and Cl were not significantly affected by the vapor barrier. Increased Ts, per se, resulted in higher excretion rates of Na, Cl, K, true creatinine and urea. Increased RH, per se, led to decreased excretion of Na, Cl, K and urea, but no effect on rate of excretion of true creatinine. The observed effect of a vapor barrier on excretion rates of these sweat solutes was therefore the net result of Ts and RH operating in opposite directions. Submitted on July 31, 1958