title: Effect of epinephrine on cAMP accumulation in cultured rat inner medullary collecting duct cells.
abstract: In a previous study we have reported the existence of alpha2- and beta-adrenoceptors in cultured rat inner medullary collecting duct (IMCD) cells. In this report, we examined the effect of epinephrine on intracellular adenosine 3',5'-cyclic monophosphate (cAMP) accumulation and evaluated whether alpha2-adrenoceptors interact with beta-receptors, vasopressin receptors, and prostaglandin (PG) E2 receptors by measuring cAMP generation. Epinephrine stimulated cAMP accumulation in a dose-dependent manner [half-maximal effective concentration (EC50) = 300 nM]. Rauwolscine (10 microM) enhanced epinephrine effects, shifting the dose-response curve for epinephrine to the left (EC50 = 120 nM); however, beta-antagonists inhibited epinephrine-induced cAMP accumulation. Epinephrine (10 microM) inhibited cAMP accumulation maximally induced by isoproterenol (10 microM); this effect was reversed by rauwolscine (10 microM). Epinephrine inhibited vasopressin (100 nM)-induced cAMP accumulation but failed to inhibit PGE2 (10 microM)-induced cAMP accumulation. We conclude that epinephrine acts as an alpha2- and beta-adrenoceptor agonist and that alpha2-adrenoceptors interact with beta-adrenoceptors and vasopressin receptors but not with PGE2 receptors on cAMP accumulation. This suggests that alpha2-adrenoceptors play a physiological role via interaction with different hormone receptors.
authors.affiliation: Second Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
authors.forename: G
authors.initials: G
authors.lastname: Yasuda
authors.forename: S
authors.initials: S
authors.lastname: Umemura
authors.forename: W B
authors.initials: WB
authors.lastname: Jeffries
mesh_terms: D000322:Adrenergic Agonists / Q000494:pharmacology*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014667:Vasopressins / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000322:Adrenergic Agonists; D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D014667:Vasopressins; D015016:Yohimbine; D000242:Cyclic AMP; D015232:Dinoprostone; D007545:Isoproterenol; D004837:Epinephrine