title: Effects of 3'-deoxycytidine on rRNA synthesis in toad bladder: analysis of response to aldosterone.
abstract: Previous studies showed that aldosterone augments transepithelial active Na+ transport and the incorporation of [3H]uridine into polyadenylated RNA (poly(A)(+)-RNA) (putatively mRNA) early in the latent period. Soon thereafter, incorporation of [methyl-14C] groups, as well as [3H]uridine into rRNA is also increased. To evaluate the role of rRNA in mineralocorticoid action, the inhibitor 3'-deoxycytidine was used in studies on the urinary bladder of the toad Bufo marinus. 3'-deoxycytidine suppressed the incorporation of [methyl-14C] and [3H]uridine into nuclear precursors of rRNA and subunits of cytoplasmic rRNA. In contrast, 3'-deoxycytidine inhibited incorporation of ]3H]uridine into cytoplasmic poly(A)(+)-RNA minimally. In control experiments, 3'-deoxycytidine had no significant effect on Na+ transport, measured as the short-circuit current (scc), when given alone. 3'-Deoxycytidine also had no significant effect on the aldosterone-dependent increase in scc. In the presence of 3'-deoxycytidine, aldosterone enhanced both the scc and the incorporation of [3H]uridine into poly(A)(+)-RNA significantly. We conclude that during the first 3 h, the mineralocorticoid action of aldosterone is not sensitive to inhibition of rRNA synthesis. Previous studies, however, implicate mRNA synthesis in this early response.
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002024:Bufo marinus; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003841:Deoxycytidine / Q000494:pharmacology*; D004347:Drug Interactions; D005260:Female; D066298:In Vitro Techniques; D011061:Poly A / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012964:Sodium / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D012335:RNA, Ribosomal; D003841:Deoxycytidine; D011061:Poly A; D000450:Aldosterone; D012964:Sodium; D014529:Uridine