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Catecholamine Stimulation of Ion Transport in the Toad Urinary Bladder
Biochimica et Biophysica Acta (BBA) - Biomembranes (1988)
  • Carl L. Thurman, University of Northern Iowa
  • J. T. Higgins, The Medical College of Ohio
Abstract
We have observed that serosal catecholamines increase the amplitude of the short-circuit current (Isc) in the toad urinary bladder by as much as 450%. Chemical sympathectomy with 106 M 6-hydroxydopamine and the sympathomimetic effects of 10−5 M tyramine indicate a reservoir of amines in the serosal stroma of the tissue. The urinary epithelium from the toad responds to six adrenoceptor agonists: (−)-epinephrine, (−)-norepinephrine, (−)-phenylephrine, clonidine, methoxamine and oxymetazoline. The α2-adrenoceptor agonist clonidine is most potent for stimulatingIsc. Some agonists were found to diminish Isc. Apparently this is related to a simultaneous increase in the transepithelial flux of both chloride and sodium. The Iscresponse to the catecholamines is also inhibited by several adrenoceptor antagonists. The α2-adrenoceptor antagonist yohimbine is more effective than the α1-antagonist prazosin for blocking the stimulation of epithelial transport. As a result of these studies, we have tentatively classified the serosal adrenoceptor of the toad urinary bladder asα2.
Keywords
  • Catecholamine,
  • Short circuit current,
  • Epithelial transport,
  • α2-Adrenoceptor,
  • Sodium ion transport,
  • Chloride ion transport
Disciplines
Publication Date
November 3, 1988
DOI
10.1016/0005-2736(88)90365-3
Citation Information
Carl L. Thurman and J. T. Higgins. "Catecholamine Stimulation of Ion Transport in the Toad Urinary Bladder" Biochimica et Biophysica Acta (BBA) - Biomembranes Vol. 945 Iss. 1 (1988) p. 81 - 91
Available at: http://works.bepress.com/carl_thurman/21/