6533b85cfe1ef96bd12bd26a

RESEARCH PRODUCT

Aufnahme und renale Ausscheidung von Wasser und Salzen bei freiem Nahrungs- und Trinkfl�ssigkeitsangebot; ihre Beeinflussung durch Adrenalektomie und Behandlung mit Nebennierenrindenhormonen bei der Ratte

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Water, sodium, potassium and chloride balances, food uptake and changes in body weight were determined in large groups of adrenalectomized or sham-operated rats having permanent access to water, 0.9 per cent saline and rat crackers. Measurements were done on the 5th to 8th day, or else on the 11th to 14th day after operation. From the 3rd day after operation the animals either received s.c. injections of 2.0 ml./kg. 0.9 per cent NaCl per day (controls) or of one of the following hormones: Corticotropin (25 U/kg. b.w./day), Cortisone acetate (12.5mg./kg./day), Cortexone acetate (7.5mg./kg./day) or D,L-Aldosterone acetate (0.15 mg./kg./day). Besides electrolyte balances, plasma concentrations and urinary excretions of endogenous “true” creatinine and urea were measured. Normal (sham-operated) rats always drank 2–3 times more 0.9 per cent saline than (distilled) water. Diuresis was about 80 per cent of total water uptake; extrarenal losses may, therefore, be assumed to be about 20 per cent of total water uptake. Body weight increased by 17 ± 3 per cent from an original average value of 180 Gm. within 20 days.Cortisone treatment in normal rats had no influence on the choice between water and saline, but did slightly increase total water uptake. It also caused an increase in urinary excretions of urea and potassium and completely suppressed growth. Treatment with cortexone consistently increased the uptake of 0.9 per cent saline without depressing the intake of pure water; diuresis, natriuresis and chloruresis were consequently increased. Urine volume in cortexone treated normal rats nearly equalled total water uptake; extrarenal water losses, therefore, were apparently diminished. Aldosterone had no measurable effect in normal rats under these conditions. Adrenalectomy prevented increases in body weight and depressed food uptake and, therefore, potassium uptake as well as urinary potassium excretion. Adrenalectomized rats did not drink more saline than normal animals, but drank definitely less pure water. Neither the urinary excretions of water nor of sodium and chloride were increased in adrenalectomized animals having permanent access to saline and water compared to normal animals. The urinary excretions of creatinine and urea decreased in adrenalectomized animals. Food uptake in adrenalectomized rats was normalized by Cortisone and Cortexone, growth by Cortexone only. The depression of pure water intake was counteracted by Cortisone, Cortexone and Aldosterone. Cortisone treatment also increased total water uptake as well as diuresis, natriuresis, chloruresis and kaliuresis in adrenalectomized rats. Cortexone had the same effects and, furthermore, considerably increased the intake of 0.9 per cent saline. Aldosterone neither increased food uptake nor 0.9 per cent saline intake in adrenalectomized rats. It depressed the urinary excretions of water, sodium and chloride. Aldosterone-treated adrenalectomized rats gained less body weight than Cortexone-treated adrenalectomized or untreated normal animals. In single-choice experiments an attempt was made to establish a preference threshold between water and NaCl solutions of 0.004 to 0.9 per cent in a large number of normal rats. No definite threshold could be determined. Neither adrenalectomy nor treatment wich Cortisone or Aldosterone definitely influenced choice between water and NaCl solutions, while Cortexone increased saline uptake in most of the salt concentrations studied. It was concluded that survival of adrenalectomized rats having free access to water and 0.9 per cent NaCl solution was due to the natural preference of this species for saline rather than to an increase in salt appetite. Furthermore, adrenalectomy had no influence on Na+ and Cl' exchanges in rats given free access to water and isotonic saline.