Metabolism of poly(A)(+)RNA in toad bladder epithelial cells.

Previous studies have characterized the induction of poly(A)(+)RNA synthesis by aldosterone during the latent period, preceding the increased active transepithelial sodium transport (measured as short-circuit current, SCC). To assess the role of aldosterone in the maintenance of the response in general and the metabolism of this RNA in particular, the decay of the increased SCC and of the newly synthesized poly(A)(+)RNA was monitored. On removal of the hormone, the SCC decayed with a half-life of 6.5 hr after a lag period of 2-3 hr. Studies on the disappearance from the cytoplasm of poly(A)(+)RNA synthesized in the first two hours after addition of aldosterone revealed a number of RNA species with diverse size decaying at a relatively slow rate after removal of aldosterone, and RNA sedimenting in the 10-14 S region decaying at a faster rate closely related to the decay in SCC. Maintenance of aldosterone in the media resulted in a much slower rate of decay of this 10-14 S. It is concluded that the decay of the 10-14 S poly(A)(+)RNA is closely related to the decay in SCC and the stability of this RNA is influenced by the retention of aldosterone in the medium.