Water and electrolyte exchange in rats exposed to cold

1968 ◽  
Vol 46 (6) ◽  
pp. 873-881 ◽  
Author(s):  
Melvin J. Fregly
Keyword(s):  
Food Intake ◽  
Water Intake ◽  
Cold Exposure ◽  
Urine Output ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Total Output ◽  
Electrolyte Loss ◽  
Sodium And Potassium ◽  
Electrolyte Exchange

Exposure of rats to air at 6 °C for 10 days increased food intake and urine output but failed to affect water intake. A comparison of water with food intake revealed a smaller water intake for a given food intake for cold-exposed than for control rats. The urine output at a given water intake was also greater for cold-exposed rats. In addition, cold exposure failed to affect urine osmolality significantly. Thus, the greater solute output accompanying cold exposure was accomplished by increasing urine flow rather than by concentrating urine. These results suggest possible mechanisms for both the relative dehydration and increased plasma osmolality observed after removal of rats from cold air. Both fecal and urinary routes of sodium and potassium excretion were increased by cold exposure; however, fecal excretions of both potassium and sodium were greater fractions of the total output during cold exposure than prior to it. Although cold exposure tends to induce a relative dehydration in rats, an important factor limiting the extent of the dehydration may be increased fecal electrolyte loss.

Effect of a Low Bulk Diet on Water and Electrolyte Exchange in Rats Exposed to Cold

1971 ◽  
Vol 49 (11) ◽  
pp. 959-966 ◽  
Author(s):  
Melvin J. Fregly
Keyword(s):  
Water Intake ◽  
Cold Exposure ◽  
Urine Output ◽  
Potassium Excretion ◽  
Drinking Response ◽  
High Bulk ◽  
Sodium And Potassium ◽  
Electrolyte Exchange

Exposure of rats to air at 6 °C for 10 days increased both intake of a low bulk diet and urine output, but failed to affect water intake. A comparison of urine output with water intake revealed a greater urine output at a given water intake in cold-exposed than in control rats. This suggests a possible mechanism for the relative dehydration induced by cold exposure. Both fecal and urinary routes of sodium and potassium excretion were increased by cold exposure. Fecal excretions of both sodium and potassium were similar fractions of their total outputs prior to, as well as during, cold exposure. In addition, both sodium and potassium exchanges were unaltered by cold exposure. These results suggest that the greater fecal sodium and potassium excretions observed previously with a high bulk food are related to fecal bulk and not to cold exposure per se.A post-cold drinking response was observed at 1, 2, and 3 h after removal from cold and is consistent with maintenance on a low bulk diet.

Effect of short-term administration of vasopressin on arterial pressure and norepinephrine turnover in Long–Evans rats

1987 ◽  
Vol 65 (10) ◽  
pp. 2142-2146 ◽  
Author(s):  
R. L. Kline ◽  
K.-Y. Chow ◽  
P. F. Mercer
Keyword(s):  
Arterial Pressure ◽  
Water Intake ◽  
Urine Output ◽  
Plasma Osmolality ◽  
Chronic Administration ◽  
Urine Osmolality ◽  
Cardiovascular Reflexes ◽  
High Dose ◽  
Normal Fluid ◽  
Long Evans

Vasopressin (AVP) in acute experiments has been shown to influence cardiovascular reflexes, but the effect of a more prolonged administration of AVP on the sympathetic nervous system has not been investigated. Long–Evans rats were treated for 7 days with AVP (Pitressin tannate in oil, with single daily doses of 100 or 500 mU∙100 g−1, s.c.) to determine whether AVP alters norepinephrine (NE) turnover in kidney, intestine, or skeletal muscle. Control rats were given equal doses of peanut oil daily. NE turnover was determined by measuring the decline in tissue levels of NE for 8 h after inhibition of tyrosine hydroxylase with α-methyl-p-tyrosine (300 mg∙kg−1, i.p. every 4 h). Measurements of water intake, urine output, and urine osmolality showed that chronic administration of the high dose, but not the low dose, of AVP produced maintained increases in urine osmolality and decreases in water intake and urine output. Body weight, plasma osmolality, plasma electrolytes, and hematocrit were not significantly altered by AVP treatment, but mean arterial pressure was elevated significantly (control, 105 ± 3 mmHg versus AVP, 119 ± 4 mmHg, p < 0.05) (1 mmHg = 133.3 Pa) in the high dose group. Plasma renin activity was decreased slightly, but significantly in rats treated with the high dose of AVP. Compared with results in control animals, there were no statistically significant changes in NE turnover after chronic administration of either the low or the high dose of AVP. The results indicate that administration of AVP for 7 days to rats in normal fluid balance does not result in a decrease in NE turnover in peripheral organs.

Renal responses to chronic cold exposure

2003 ◽  
Vol 81 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Zhongjie Sun ◽  
Zhonge Zhang ◽  
Robert Cade
Keyword(s):  
Food Intake ◽  
Cold Exposure ◽  
Water Loss ◽  
Urine Output ◽  
Room Temperature ◽  
Urine Osmolality ◽  
Urine Flow ◽  
Receptor Mrna ◽  
The Difference ◽  
Renal Responses

The aim of this study was to assess our hypothesis that the release of antidiuretic hormone (ADH), the renal concentrating response to ADH, or both is decreased by prolonged cold exposure. Six groups (n = 6/group) of rats were used. Three groups were exposed to cold (5°C), while the remaining three groups were kept at room temperature (25°C). It was found that urine osmolality decreased significantly and serum osmolality increased significantly during cold exposure. The ratio of water/food intake was not affected by prolonged cold exposure. However, prolonged cold exposure increased the ratio of urine output/food intake in the cold-exposed rats, indicating that more urine flow is required by the cold-exposed rats to excrete the osmotic substance at a given food intake. The difference between water intake and urine output decreased significantly in the cold-exposed rats. Thus, prolonged cold exposure increases water loss from excretion. Renal concentrating responses to 24-h dehydration and Pitressin were decreased significantly in the cold-exposed rats. Plasma ADH levels remained unchanged, but renal ADH receptor (V2 receptor) mRNA was decreased significantly in the cold-exposed rats. The results strongly support the conclusion that cold exposure increases excretive water loss, and this may be due to suppression of renal V2 receptors rather than inhibition of ADH release.Key words: renal concentrating response, cold-induced dehydration, serum and urine osmolality, ADH, renal V2 receptor mRNA.

scholarly journals Urine and Plasma Osmolality in Patients with Autosomal Dominant Polycystic Kidney Disease: Reliable Indicators of Vasopressin Activity and Disease Prognosis?

2015 ◽  
Vol 41 (3) ◽  
pp. 248-256 ◽  
Author(s):  
Niek F. Casteleijn ◽  
Debbie Zittema ◽  
Stephan J.L. Bakker ◽  
Wendy E. Boertien ◽  
Carlo A. Gaillard ◽  
...  
Keyword(s):  
Water Intake ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Kidney Volume ◽  
Polycystic Kidney ◽  
Estimated Gfr ◽  
Total Kidney Volume ◽  
Autosomal Dominant Polycystic Kidney ◽  
Crude Analysis

Background: Vasopressin plays an essential role in osmoregulation, but has deleterious effects in patients with ADPKD. Increased water intake to suppress vasopressin activity has been suggested as a potential renoprotective strategy. This study investigated whether urine and plasma osmolality can be used as reflection of vasopressin activity in ADPKD patients. Methods: We measured urine and plasma osmolality, plasma copeptin concentration, total kidney volume (TKV, by MRI) and GFR (125I-iothalamate). In addition, change in estimated GFR (eGFR) during follow-up was assessed. Results: Ninety-four patients with ADPKD were included (56 males, age 40 ± 10, mGFR 77 ± 32 ml/min/1.73 m2, TKV 1.55 (0.99-2.40) l. Urine osmolality, plasma osmolality and copeptin concentration were 420 ± 195, 289 ± 7 mOsmol/l and 7.3 (3.2-14.6) pmol/l, respectively. Plasma osmolality was associated with copeptin concentration (R = 0.54, p < 0.001), whereas urine osmolality was not (p = 0.4). In addition, urine osmolality was not associated with TKV (p = 0.3), in contrast to plasma osmolality (R = 0.52, p < 0.001) and copeptin concentration (R = 0.61, p < 0.001). Fifty-five patients were followed for 2.8 ± 0.8 years. Baseline plasma and urine osmolality were not associated with change in eGFR (p = 0.6 and p = 0.3, respectively), whereas baseline copeptin concentration did show an association with change in eGFR, in a crude analysis (St. β = -0.41, p = 0.003) and also after adjustment for age, sex and TKV (St. β = -0.23, p = 0.05). Conclusions: These data suggest that neither urine nor plasma osmolality are valid measures to identify ADPKD patients that may benefit from increasing water intake. Copeptin appears a better alternative for this purpose.

scholarly journals The Vasopressin System in the Risk of Diabetes and Cardiorenal Disease, and Hydration as a Potential Lifestyle Intervention

2018 ◽  
Vol 72 (Suppl. 2) ◽  
pp. 21-27 ◽  
Author(s):  
Sofia Enhörning ◽  
Olle Melander
Keyword(s):  
Type 2 Diabetes ◽  
Water Intake ◽  
Kidney Diseases ◽  
Urine Volume ◽  
Plasma Osmolality ◽  
Premature Mortality ◽  
Urine Osmolality ◽  
High Plasma ◽  
Effective Prevention

Background: Type 2 diabetes, chronic kidney disease (CKD) and its cardiovascular complications are increasing as health problems worldwide. These diseases are interrelated with overlapping occurrence and once diabetes is established, the risk of cardiorenal disease is dramatically elevated. Thus, a search for unifying modifiable risk factors is key for effective prevention. Summary: Elevated fasting plasma concentration of vasopressin, measured with the marker copeptin, predicts new onset type 2 diabetes as well as renal function decline. Furthermore, we recently showed that increased plasma copeptin concentration independently predicts the development of both CKD and other specified kidney diseases. In consequence, high copeptin is an independent risk factor for cardiovascular disease and premature mortality in both diabetes patients and in the general population. Vasopressin is released when plasma osmolality is high, and the easiest way to lower plasma vasopressin and copeptin concentration is to increase water intake. In a human water intervention experiment with 1 week of 3 L/day increased water intake, the one third of the participants with the greatest copeptin reduction (water responders) were those with a phenotype of low water intake (high habitual plasma copeptin and urine osmolality, and low urine volume). The water-responders had a copeptin reduction of 41% after 1 week of increased water intake compared to a control week; in contrast, a 3% reduction occurred in the other two thirds of the study participants. Among water responders, increased water intake also induced a reduction in fasting glucagon concentration. Key Messages: Elevated copeptin, a measure of vasopressin, is a risk marker of metabolic and cardiorenal diseases and may assist in the detection of individuals at higher risk for these diseases. Furthermore, individuals with high copeptin and other signs of low water intake may experience beneficial glucometabolic effects of increased water intake. Future randomized control trials investigating effects of hydration on glucometabolic and renal outcomes should focus on individuals with signs of low water intake including high plasma copeptin concentration.

Genetic AVP deficiency abolishes cold-induced diuresis but does not attenuate cold-induced hypertension

2006 ◽  
Vol 290 (6) ◽  
pp. F1472-F1477 ◽  
Author(s):  
Zhongjie Sun
Keyword(s):  
Cold Exposure ◽  
Urine Output ◽  
Room Temperature ◽  
Control Period ◽  
Free Water ◽  
Renal Medulla ◽  
Urine Osmolality ◽  
Free Water Clearance ◽  
Receptor Mrna ◽  
Induced Hypertension

Chronic cold exposure causes hypertension and diuresis. The aim of this study was to determine whether vasopressin (AVP) plays a role in cold-induced hypertension and diuresis. Two groups of Long-Evans (LE) and two groups of homozygous AVP-deficient Brattleboro (VD) rats were used. Blood pressure (BP) was not different among the four groups during a 2-wk control period at room temperature (25°C, warm). After the control period, one LE group and one VD group were exposed to cold (5°C); the remaining groups were kept at room temperature. BP and body weight were measured weekly during exposure to cold. Food intake, water intake, urine output, and urine osmolality were measured during weeks 1, 3, and 5 of cold exposure. At the end of week 5, all animals were killed and blood was collected for measurement of plasma AVP. Kidneys were removed for measurement of renal medulla V2 receptor mRNA and aquaporin-2 (AQP-2) protein expression. BP of LE and VD rats increased significantly by week 2 of cold exposure and reached a high level by week 5. BP elevations developed at approximately the same rate and to the same degree in LE and VD rats. AVP deficiency significantly increased urine output and solute-free water clearance and decreased urine osmolality. Chronic cold exposure increased urine output and solute-free water clearance and decreased urine osmolality in LE rats, indicating that cold exposure caused diuresis in LE rats. Cold exposure failed to affect these parameters in VD rats, suggesting that the AVP system is responsible for cold-induced diuresis. Cold exposure did not alter plasma AVP in LE rats. Renal medulla V2 receptor mRNA and AQP-2 protein expression levels were decreased significantly in the cold-exposed LE rats, suggesting that cold exposure inhibited renal V2 receptors and AVP-inducible AQP-2 water channels. We conclude that 1) AVP may not be involved in the pathogenesis of cold-induced hypertension, 2) the AVP system plays a critical role in cold-induced diuresis, and 3) cold-induced diuresis is due to suppression of renal V2 receptors and the associated AQP-2 water channels, rather than inhibition of AVP release.

scholarly journals Acute Increases in Water Consumption Supress Copeptin in Low Drinkers

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1389-1389
Author(s):  
Abigail Colburn ◽  
Adam Seal ◽  
HyunGyu Suh ◽  
Stavros Kavouras
Keyword(s):  
Water Intake ◽  
Water Consumption ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Acute Effect ◽  
State University ◽  
Effect Of Water ◽  
Funding Sources ◽  
Bottom Quartile ◽  
Main Effect

Abstract Objectives To assess the acute effect of adequate water consumption on copeptin, a marker of arginine vasopressin, in low drinkers. Methods Six healthy (5 males, 1 female) low drinkers (age 43 ± 7 y, BMI 30.5 ± 3) were recruited based on self-reported daily water consumption ≤1.5 L·day−1 in males or 1.0 L·day−1 in females (854 ± 432 mL·d−1) and 24-h urine osmolality ≥800 mmol·kg−1 (968 ± 114 mmol·kg−1). Participants completed two counterbalanced crossover 11-h protocols. They were provided either the Institute of Medicine's recommended amount of water excluding food (males: 3 L, females: 2 L, HWI) or an amount representing the bottom quartile of water consumption observed in the National Health and Nutrition Examination Survey (males: 0.5 L, females: 0.4 L, LWI). Food was provided to participants and standardized to body weight (100 kJ·Kg−1) using a consistent ratio of macronutrients. Blood samples were collected at hours 700, 800, 900, 1200, 1300, 1400, 1600, 1700, and 1800. Results There was a significant main effect of water intake on plasma osmolality (F = 11.838, P = 0.018) with greater values in LWI at 1200 (HWI: 287 ± 3, LWI: 291 ± 3; P = 0.013), 1400 (HWI: 287 ± 4, LWI: 291 ± 5; P = 0.049), and 1700 (HWI: 287 ± 2, LWI: 292 ± 4; P = 0.004). There was also a significant main effect of water intake on copeptin (F = 9.848, P = 0.026) with higher values in LWI at 0800 (HWI: 6.1 ± 2.3, LWI: 8.7 ± 3.7; P = 0.016), 0900 (HWI: 5.3 ± 2.4, LWI: 9.2 ± 4.5; P = 0.013), 1200 (HWI: 4.2 ± 1.9, LWI: 7.8 ± 4.6; P = 0.021), 1400 (HWI: 4.3 ± 1.8, LWI: 8.3 ± 4.7; P = 0.033), 1600 (HWI: 4.7 ± 2.5, LWI: 7.6 ± 4.5; P = 0.049), and 1800 (HWI: 4.4 ± 2.5, LWI: 7.8 ± 5.2; P = 0.048). Water intake did not influence change in plasma volume (P = 0.214). Conclusions Copeptin was suppressed in response to acute increases in water consumption via suppression of plasma osmolality. Copeptin may serve as a sensitive marker for changes in total water intake. Funding Sources This study was supported by Arizona State University College of Health Solutions.

Role of vasopressin in fetal homeostasis

1982 ◽  
Vol 242 (6) ◽  
pp. F740-F744
Author(s):  
S. S. Daniel ◽  
R. I. Stark ◽  
M. K. Husain ◽  
L. V. Baxi ◽  
L. S. James
Keyword(s):  
Urine Output ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Maternal Plasma ◽  
Third Trimester ◽  
The Third ◽  
Plasma Vasopressin ◽  
The Relationship ◽  
Linear Correlations

The role of vasopressin (VP) and the kidney in the maintenance of solute and volume homeostasis was studied in chronically instrumented fetal lambs during the third trimester. Plasma VP, urine and plasma osmolality, and urine output were measured in 74 simultaneous samples. The results show a strong positive nonlinear correlation between plasma VP and osmolality when a latter is higher than 290 mosmol/kg (r = 0.803, P = 0.03) and between plasma VP and urine osmolality (r = 0.806, P = 0.05). No correlation was found between fetal and maternal plasma VP. However, linear correlations were found in plasma osmolality and sodium concentrations between mother and fetus; mean maternal-fetal gradients were 4 mosmol/kg and 3.1 meq/liter, respectively. The highest values for plasma VP and osmolality found in our study were 7.0 pg/ml and 317 mosmol/kg, respectively. There values corresponded to urine output of 0.02 ml.kg-1.min-1 and osmolality of 517 mosmol/kg. In conclusion, there studies demonstrate that the relationship among plasma osmolality, plasma vasopressin concentration, and urine osmolality in the lamb fetus are qualitatively similar to those of the adult. The results suggest that the fetal neurohypophysis and kidney may participate in the maintenance of fetal osmolar and volume homeostasis.

WATER INTAKE OF RATS IMMEDIATELY AFTER EXPOSURE TO A COLD ENVIRONMENT

1966 ◽  
Vol 44 (4) ◽  
pp. 651-662 ◽  
Author(s):  
Melvin J. Fregly ◽  
Irving W. Waters
Keyword(s):  
Food Intake ◽  
Water Intake ◽  
Cold Exposure ◽  
Fluid Intake ◽  
Daily Intake ◽  
Chloride Concentration ◽  
Cold Environment ◽  
Exposure To Cold ◽  
The Relationship

Rats exposed to air at 6 °C for 1, 3, 6, 10, and 12 days manifested an apparent "thirst" upon return to a warm (26 °C) environment. Drinking began within 80 minutes and continued for at least 24 hours after removal from the cold. Up to 10% of the 24-hour fluid intake was ingested within one-half hour after removal from the cold. During exposure to cold for 1 to 3 days, water intake either remained unchanged or decreased compared with values obtained before cold exposure, while food intake increased within 24 hours. The relationship between simultaneous daily intake of food and water was altered significantly by cold such that less water was ingested for a given food intake during exposure to cold than before exposure. A state of dehydration relative to controls may be present in cold-exposed rats as suggested by their decreased water intake for a given food intake and by increases in both osmolality and chloride concentration of serum. The increased water intake immediately after removal from the cold may be a manifestation of the relative dehydration. However, persistence of an increased water intake up to 24 hours after removal from the cold is unexplained.

Food intake, water intake, urine output, growth rate and wool growth of lambs accustomed to high or low intake of sodium chloride

1987 ◽  
Vol 38 (1) ◽  
pp. 187 ◽  
Author(s):  
JA Hamilton ◽  
MED Webster
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Water Intake ◽  
Urine Output ◽  
Experimental Period ◽  
Oral Route ◽  
Output Growth ◽  
High Intake ◽  
Wool Production ◽  
Intake Water

Lambs artificially reared were given either no salt supplement (LS lambs) or 2.0 g NaCl supplementation (kg body weight)-1 (HS lambs) by oral route from an early age. The food intake, water intake, urine output, growth rate and wool production were measured for several months to identify any changes in the performance of the lambs. Growth rate of HS lambs, although relatively high, was significantly less (P < 0.001) than in LS lambs, owing mainly to HS lambs having a reduced food intake. Linear relationships between water and food intakes were maintained, but shifted to a new plane for the HS lambs. The high intake of NaCl caused water intake to increase, which appeared to be mostly used to excrete the NaCl through increased urine output. Lambs given a high intake of NaCl had a lower food intake, but the reasons for the reduction could not be defined in this experiment. Wool production was reduced, but not significantly, by a high intake of NaCl. Diarrhoea was observed on more than one occasion in HS lambs during the experimental period.

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