Faculty Publications

Catecholamine Stimulation of Ion Transport in the Toad Urinary Bladder

Document Type

Article

Journal/Book/Conference Title

Biochimica et Biophysica Acta (BBA) - Biomembranes

Volume

945

Issue

1

First Page

81

Last Page

91

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 stimulating Isc. 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 Isc response 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 as α2.

Department

Department of Biology

Original Publication Date

11-3-1988

DOI of published version

10.1016/0005-2736(88)90365-3

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