The mechanism of water diuresis in normal rats and rabbits as analysed by inulin and diodone clearances

SUMMARY1. The time course and extent of changes in urinary flow and in the outputs of urea, Na+, K+, and NH+ over a period of 71 hr in conscious rats during water and osmotic (mannitol) diuresis were determined, and compared with spontaneous changes in non-diuretic animals.2. In non-diuretic rats, a morning rise and subsequent decline in urinary osmolal, sodium, potassium and ammonium outputs occurred, possibly attributable to circadian rhythms.3. Water diuresis was accompanied by (i) a rapid increase in urea excretion during the phase of increasing urine flow, followed by a fall in later periods to values similar to those in non-diuresis, (ii) a slower increase in sodium output, continuing after the establishment of the constant water load, (iii) unchanged potassium excretion, but slightly increased ammonium outputs.

Section: Discussionmentioning

confidence: 99%

Effects of water diuresis and osmotic (mannitol) diuresis on urinary solute excretion by the conscious rat

Atherton¹,

Hai²,

Thomas³

1968

“…It is a puzzling fact that during water diuresis the rate of glomerular filtration and that of urine flow are correlated in the rabbit (Kaplan & Smith, 1935; Wilkinson & McCance, 1940;Dicker & Heller, 1945;Forster, 1947), while no such correlation has been found in another species of rodent, viz. the adult rat fed on an adequate diet (Dicker & Heller, 1945;Dicker, 1949).…”

Section: Discussionmentioning

confidence: 99%

“…the adult rat fed on an adequate diet (Dicker & Heller, 1945;Dicker, 1949). As shown recently by Dicker & Heller (1950), the glomerular component in the regulation of the urine volume in rabbits appears to be a physiological response in this species.…”

Section: Discussionmentioning

confidence: 99%

The mechanism of water diuresis in adult and newborn guinea‐pigs

Dicker¹,

Heller²

1951

Self Cite

Recent work in renal physiology has emphasized species differences in mammalian kidney function. It seemed, therefore, of interest to investigate the kidney of the guinea-pig which, in this respect, has so far been neglected. All that appears to be known is that the time relations of water diuresis in adult guinea-pigs resemble those of the rat rather than those of the rabbit (Heller & Smirk, 1932 Adult guinea-pigs were given 5-0 ml./100 g. body weight of tepid water by stomach tube and were then injected subcutaneously with 2-0 ml./100 g. body weight of a 5% solution of inulin. Handling, prodding or, even suprapubic pressure failed to induce emptying of the bladder; it was therefore necessary to rely on spontaneous micturition. Spontaneous emptying of the bladder occurred readily after water administration. The voiding of the bladder which occurred 90 to 105 min. after the water had been given, i.e. during the peak of the water diuresis (Heller & Smirk, 1932) was taken as the beginning ofthe urine collecting period. A second micturition ( =end of the urine collecting period) occurred spontaneously between 14 and 27 min. after the first. The average time of collecting period amounted to 20-0± 1-7 min. (s.E. of nineteen observations). Immediately after the second micturition the animal was killed and blood collected from the jugular and carotid vessels. Heparinized plasma was used throughout.Inulin excretion by newborn guinea-pigs Newborn guinea-pigs cannot be made to empty their bladder at regular intervals, and even after spontaneous micturition their bladder is not quite empty. To collect urine quantitatively the newborn animals had to be killed and the urine withdrawn by bladder puncture. Short urine collecting periods for the estimations of inulin clearances were thus impossible. To overcome this difficulty, the following method was used: newborn guinea-pigs were given 5 0 ml./100 g. body weight of tepid tap water by stomach tube and injected subcutaneously with 2-0 ml./100 g. of

“…The routine procedure conformed on the whole with that described previously (Dicker & Heller, 1945) but differed in the following respect: 1-0 ml./100 g. body weight of a 5 % solution of imulin in physiological saline was injected intramuscularly, followed immediately by the administration of 5 % of body weight of water by stomach tube. Fifty minutes after water administration the bladder was emptied and the urinecollecting period started; the latter varied between 10 and 15 min.…”

Section: Methodsmentioning

confidence: 99%

“…has been shown (Dicker & Heller, 1945) that the kidney function of adult rats, fed on a standard diet, resembled that of the dog, i.e. the rate of glomerular filtration in rats is independent of that of urine flow.…”

mentioning

confidence: 99%

Effect of the protein content of the diet on the glomerular filtration rate of young and adult rats

Dicker¹

1949

Self Cite

It. has been shown (Dicker & Heller, 1945) that the kidney function of adult rats, fed on a standard diet, resembled that of the dog, i.e. the rate of glomerular filtration in rats is independent of that of urine flow. In rats fed on a proteindeficient vegetable diet, however, and suffering from severe hypoproteinaemia, the glomerular filtration rate was found to vary with the urine flow-(Dicker, Heller & Hewer, 1946). An investigation of the kidney function of normal rats on diets containing different amounts of protein and thus producing different plasma-protein concentrations seemed therefore of interest. METHODSExperimental animals. Twenty-nine young rats with weights varying from 101 to 150 g. and ninety-one adult rats with weights from 260 to 350 g. were used.Diets. The animals were fed on different types ofdiet, yielding comparable amounts of calories but containing varying amounts of protein.Diet I (D. I) had the following composition: wheat offal 19-2 %, ground wheat 19-2 %, finely ground oats 19.2%, ground maize 9.5%, ground barley 9.5%, white fish meal 4-8%, meat and bone meal 9.5 %, dried skimmed milk 7.0 %, dried yeast 1-3 %, salt 0.4 % and cod-liver oil 0.4%. 100 g. of this food yielded 305-8 calories. Diet II (D. II) differed from D. I by its higher content of dried skimmed milk, viz.14% instead of 7 %. Its composition was so adjusted as to have the same calorific value as D. I. Diet III (D. III) had the following composition: casein 18%, starch 53%, dried yeast 15-0%, ground-nut oil 8-0%, cod-liver oil 2-0%, salt mixture 4-0%. 100 g. of this diet yielded 303-0 calories. Diet IV (D. IV) differed from D. III by its higher content of casein, viz. 25-0% instead of 18%/. Litter-mates were fed on diet D. II until they reached the required weight (101-150 g.). Series of adult rats were fed on the different diets described for 9 weeks.Experimentalproceduresfor the determination ofinulin clearances. The routine procedure conformed on the whole with that described previously (Dicker & Heller, 1945) but differed in the following respect: 1-0 ml./100 g. body weight of a 5 % solution of imulin in physiological saline was injected intramuscularly, followed immediately by the administration of 5 % of body weight of water by stomach tube. Fifty minutes after water administration the bladder was emptied and the urinecollecting period started; the latter varied between 10 and 15 min. according to the urine flow of the rat. The equilibrium reached 50 min. after the injection was satisfactory: the level of inulin in the plasma did not vary significantly during the period of urine collection. Immediately after the PH. CVIII. 13