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The Effect of cAMP on Electrogenic Na+ Absorption in the Rat Distal Colon

Jpn J Physiol Vol.51, No.4 pp.435-444
Yo Tsuchiya, Yuichi Suzuki
Abstract: Cyclic AMP is a ubiquitous second messenger produced in cells in response to extracellular stimulants. The aim of this study was to examine its role in the regulation of amiloride-sensitive electrogenic Na+ absorption in the rat distal colon by measuring the short-circuit current (Isc) and 22Na+ fluxes in a chamber-mounted mucosal sheet. Forskolin stimulated the amiloride-inhibitable Isc and amiloride-inhibitable 22Na+ absorption. 8Br-cAMP also stimulated the amiloride-inhibitable Isc. Furthermore, isoproterenol, acting via -adrenergic activation, stimulated the amiloride-inhibitable Isc. The isoproterenol-induced increase in the amiloride-sensitive Isc was largely suppressed by H89, a protein kinase A inhibitor. In conclusion, cAMP can upregulate amiloride-sensitive electrogenic Na+ absorption in the rat distal colon.

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Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, 422-8526 Japan. yuichi@smails.u-shizuoka-ken.ac.jp
Copyright© 2007 by The Physiological Society of Japan