Abstract
RNA synthesis, carbonic anhydrase and ATPase activities in the kidney and urinary excretion of sodium after the administration of aldosterone and actinomycin D to adrenalectomized mice were examined to clarify the physiological significance of above enzymes in “induction hypothesis of aldosterone” with the following results.
1. Stimulatory effect of aldosterone (2 μg/kg, s. c.) on kidney RNA synthesis, especially on nuclear RNA, was blocked by the pretreatment with actinomycin D (300 μg/kg, i. p.).
2. Elevation of kidney carbonic anhydrase activity and depression of urinary excretion of 22Na induced by aldosterone alone were blocked by the combined administration of actinomycin D.
3. Administration of actinomycin D alone to adrenalectomized mice had no effect on both kidney carbonic anhyrase activity and urinary excretion of 22Na.
4. Kidney microsomal ATPase activity was unaltered by aldosterone and actinomycin D, alone or in combination.
In conclusion, above results seem to suggest the important role of carbonic anhydrase as a mediator of action of aldosterone on the depression of urinary excretion of sodium in adrenalectomized mice.
