SECRETORY RATES OF ALDOSTERONE IN SODIUM-DEPLETED CALVES

The double isotope dilution derivative technique was used to measure concentrations of aldosterone in adrenal venous blood collected quantitatively from the right adrenal gland of male Holstein-Friesian calves. Aldosterone secretory rates were determined in normal calves and in calves depleted of Na for 7 or 14 days. Na depletion was achieved by uncom-pensated loss of saliva through a fistula of a parotid salivary duct and reduction of dietary NaCl intake. The mean aldosterone secretory rate in 5 control calves was 0.08 [mu]g, ([plus or minus] 0.03 s.d.)/minute/gland. The mean secretory rate in 4 calves after 7 days of Na depletion was 0.70 [mu]g. ([plus or minus] 0.38 s.d.)/minute/gland. After the 14-day depletion period, the mean aldosterone secretory rate obtained from 5 calves was 1.06 [mu]g. ([plus or minus] 0.90 s.d.)/minute/gland. The production of aldosterone by incubated slices of adrenal gland obtained from these calves was also measured. Production was 1.5 to 2.0 times greater in the adrenal slices from Na-depleted calves than in those from control calves.