title: Potassium secretion by rabbit descending colon: effects of adrenergic stimuli.
abstract: Stripped rabbit distal colonic mucosa was studied in vitro in Ussing chambers to investigate the effects of adrenergic stimuli on Na+, K+, and Cl- transport. The adrenergic stimuli epinephrine and norepinephrine decrease short-circuit current in a dose-dependent manner, with a half-maximal effect at 5 X 10(-7) M and a maximal effect between 10(-5) and 10(-4) M. The effects produced by norepinephrine and epinephrine can also be elicited by the beta 1-agonist dobutamine, but not by the beta 2-agonist terbutaline or the alpha-agonist phenylephrine. In addition, the effects of adrenergic stimulation can be inhibited by the beta-antagonist propranolol but not by the muscarinic antagonist atropine, the alpha 2-antagonist yohimbine, or tetrodotoxin. The decrease in short-circuit current elicited by adrenergic stimuli is accompanied by an increase in net K+ secretion with no change in net Cl- or Na+ transport. This increase in net K+ secretion elicited by beta-adrenergic stimulation can be inhibited by trifluoperazine but not by indomethacin. These studies suggest that K+ transport by the colon can be regulated by adrenergic agents acting via beta 1-receptors.
authors.forename: P L
authors.initials: PL
authors.lastname: Smith
authors.forename: R D
authors.initials: RD
authors.lastname: McCabe
mesh_terms: D000527:Alprostadil / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D004280:Dobutamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D013566:Sympathomimetics / Q000494:pharmacology*; D013726:Terbutaline / Q000494:pharmacology
chemical_list: D002712:Chlorides; D013566:Sympathomimetics; D010656:Phenylephrine; D000001:Calcimycin; D004280:Dobutamine; D000584:Amiloride; D012964:Sodium; D000527:Alprostadil; D013726:Terbutaline; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine