Induction of RNA and protein synthesis in the action of aldosterone in the rat

Abstract

The present studies were intended to provide additional information on the role of RNA and protein synthesis in the response to aldosterone in adrenalec -tomized rats. The conditions necessary to obtain reproducible responses to aldosterone in unanesthetized, uncatheterized rats were defined and under these conditions, there was a latent period of 1 hr. in both antinatriuresis and kaliuresis, and a progressive response to maximum levels 3 hr. after injection of aldosterone. Actinomycin D (30 ug/100 g body wt.) significantly inhibited the antinatriuretic response to aldosterone but had no effect on the kaliuretic response. At 90 min. after injection, renal homogenates taken from aldosterone-treated rats showed enhanced incorporation of orotate-3H into RNA of the nuclear and supernatant fractions. Injection of estradiol-17B had no effect on nuclear RNA synthesis in renal homogenates. The addition of actinomycin D to the homogenates inhibited incorporation of orotate-3H into nuclear RNA to a greater extent than in the other cell fractions. Aldosterone, in vivo, also increased incorporation of leucine-3H into microsomal proteins whereas estradiol-17B did not. These results are consistent with the proposal that steroidal stimulation of RNA and protein synthesis mediates mineralocorticoid action on Na excretion.