Role of RNA in the action of aldosterone on Na+ transport

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Abstract
Recent data describing the effects of aldosterone on the induction of messenger RNA (=mRNA) and ribosomal RNA (=rRNA) are reviewed. In the urinary bladder of the toad, aldosterone induces a few specific polyadenylatedmRNAs (=poly(A)(+)mRNA) during the latent period, i.e., 30 to 60 min after hormone addition. Later, i.e., 90 to 240 min after aldosterone addition, 18S and 28S cytoplasmicrRNA subunits are also induced. The effect on poly(A)(+)mRNA is mineralocorticoid-specific and correlates well with the aldosterone-dependent Na+ transport. Actinomycin D which inhibits both poly(A)(+)mRNA and nonpolyadenylatedmRNA (=poly(A)(−)mRNA) totally abolishes the response to aldosterone on Na+ transport. 3′deoxyadenosine (cordycepin), which inhibits poly(A)(+)mRNA but not poly(A)(−)mRNA, only inhibits 50 to 60% of the physiological response. These differential effects suggest that an intact poly(A)(−)mRNA pathway is also an important factor in mediating the action of aldosterone. In contrast, 3′deoxycytidine, which inhibitsrRNA but notmRNA, does not impair the mineralocorticoid response, at least during the first 3 hr of aldosterone action.