Abstract
1. Time-course of effect of aldosterone (2μg/kg, s.c.) on kidney, liver and blood carbonic anhydrase activity and kidney microsomal ATPase activity from adrenalectomized mice was examined until 16 hr after injection. Elevation of kidney carbonic anhydrase activity appeared at about 1.5 hr after hormone administration and its maximum was observed 4 hr later with a gradual return to initial levels thereafter. Activity of liver carbonic anhydrase showed a conversed behaviour compared with that of kidney carbonic anhydrase. Blood carbonic anhydrase and ATPase activities were not affected by aldosterone.
2. Decrease of urinary excretion of 22Na by aldosterone (0.5-20μg/kg) appeared at 2 hr after hormone injection and continued until 4 hr later without significant changes thereafter.
3. Acetazolamide (20mg/kg, i.p.) inhibited the kidney carbonic anhydrase activity and increased the urinary excretion of 22Na and the maximum effect was observed at about 3-4 hr after the injection of acetazolamide.
4. These results suggest the following inference that a part of the inhibitory effect of aldosterone on urinary excretion of sodium may be mediated by the activation of kidney carbonic anhydrase.
