title: Adenylate cyclase activity in cultured epithelial cells.
abstract: The cyclic AMP metabolism of cultured epithelial cells was investigated. Epinephrine or 1-methyl,3-isobutylxanthine (MIX) alone had no effect on cyclic AMP levels in intact cells, whereas the combination of the two agents yielded a 6- to 10-fold increase in cyclic AMP levels. Both basal and stimulated cyclic AMP levels decreased with increasing cell density. Cell-free adenylate cyclase preparations were stimulated markedly by epinephrine or isoproterenol in the absence of MIX. Since the epithelial cells were found to have a relatively small amount of cyclic nucleotide phosphodiesterase (PDE) activity, the requirement for MIX to visualize intact cell responsiveness to epinephrine could be explained only partially by its PDE inhibitory properties.
mesh_terms: D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002474:Cell-Free System; D000242:Cyclic AMP / Q000096:biosynthesis; D004837:Epinephrine / Q000494:pharmacology; D004848:Epithelium / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D013268:Stimulation, Chemical; D014970:Xanthines / Q000494:pharmacology
chemical_list: D014970:Xanthines; D000242:Cyclic AMP; D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine