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Urinary sodium excretion and the renin‐aldosterone system in new‐born calves.
Author(s) -
Safwate A
Publication year - 1985
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1985.sp015675
Subject(s) - aldosterone , endocrinology , medicine , excretion , plasma renin activity , chemistry , hydrochlorothiazide , renin–angiotensin system , urinary system , reabsorption , renal physiology , sodium , diuretic , kidney , blood pressure , organic chemistry
Urinary Na+ and K+ excretion, plasma aldosterone levels (PAL) and plasma renin activity (PRA) were measured in three groups of four 3‐day‐old calves infused with aldosterone, ethacrynic acid and hydrochlorothiazide or with vehicle. Aldosterone infusion (16.7 micrograms/kg body wt. given by rapid injection, followed by the infusion of 33.3 micrograms/kg body wt. during 6 h) decreased urinary Na+ concentration and excretion during the 6 h period of infusion. This effect disappeared during the following 18 h. Ethacrynic acid (2 mg/kg body wt. by rapid injection, followed by the infusion of 1.5 mg/kg body wt..h during 6 h) and hydrochlorothiazide (8 mg/kg body wt. by rapid injection, followed by the infusion of 6 mg/kg body wt..h during 6 h) increased urinary volume and urinary excretion of Na+, but decreased urinary K+ concentration without affecting urinary K+ excretion during the 6 h period of infusion. During the same time, the plasma Na+ concentration decreased, PRA increased rapidly and was followed by a significant rise in PAL. These results demonstrate that in very young healthy calves, the renal tubules are able to respond to aldosterone. The renin‐aldosterone system is also operative in these animals since it responds to Na+ depletion induced by the combination of diuretics and inhibitors of tubular Na+ reabsorption.