AJP - Cell Physiology, Vol 269, Issue 2 C464-C471, Copyright © 1995 by American Physiological Society

ARTICLES

Reconstitution of a KATP channel from basolateral membranes of Necturus enterocytes

O. Mayorga-Wark, W. P. Dubinsky and S. G. Schultz
Department of Integrative Biology, University of Texas Medical School at Houston 77225, USA.

We have previously reported that basolateral membrane vesicles isolated from Necturus maculosa small intestinal epithelial cells and incorporated into planar phospholipid bilayers display a highly selective "maxi"-conductance K+ channel whose open-time probability is affected by voltage. We now report that this channel is inhibited by MgATP in the solution bathing the intracellular face of the channel but not by Mg2+ or the Na+ or K+ salts of ATP; the effects of MgATP can be prevented or reversed by MgADP. The channel is also inhibited by the nonhydrolyzable ATP analogue magnesium adenosine 5'-O-(3-thiotriphosphate) and the sulfonylurea derivatives tolbutamide and glibenclamide; all of these agents are effective in the intracellular compartment but not when added to the extracellular compartment alone. Channel activity is stimulated by the "K+ channel opener," diazoxide, which also reverses the effect of glibenclamide but not of MgATP. The possible role of this channel as a mediator of the parallelism between basolateral membrane Na(+)-K+ pump activity and the macroscopic K+ conductance of that barrier is discussed.

This article has been cited by other articles:

				D. Heitzmann and R. Warth Physiology and Pathophysiology of Potassium Channels in Gastrointestinal Epithelia Physiol Rev, July 1, 2008; 88(3): 1119 - 1182. [Abstract] [Full Text] [PDF]

				M. Wegmann, A. Kämpen, S. Weber, H. W. Seyberth, and A. Köckerling Effect of Hydroxyeicosatetraenoic Acids on Furosemide-Sensitive Chloride Secretion in Rat Distal Colon J. Pharmacol. Exp. Ther., October 1, 2000; 295(1): 133 - 138. [Abstract] [Full Text]

				W. P. Dubinsky, O. Mayorga-Wark, and S. G. Schultz Volume regulatory responses of basolateral membrane vesicles from Necturus enterocytes: Role of the cytoskeleton PNAS, August 3, 1999; 96(16): 9421 - 9426. [Abstract] [Full Text] [PDF]

				W. P. Dubinsky, O. Mayorga-Wark, and S. G. Schultz Colocalization of glycolytic enzyme activity and KATP channels in basolateral membrane of Necturus enterocytes Am J Physiol Cell Physiol, December 1, 1998; 275(6): C1653 - C1659. [Abstract] [Full Text] [PDF]

				J. Denton, D. Boahene, and W. M. Moran Luminal L-alanine stimulates exocytosis at the K+-conductive apical membrane of Aplysia enterocytes Am J Physiol Cell Physiol, November 1, 1998; 275(5): C1300 - C1312. [Abstract] [Full Text] [PDF]

				M. D. DuVall, Y. Guo, and S. Matalon Hydrogen peroxide inhibits cAMP-induced Cl- secretion across colonic epithelial cells Am J Physiol Cell Physiol, November 1, 1998; 275(5): C1313 - C1322. [Abstract] [Full Text] [PDF]

				D. X. Zhang, Y.-F. Chen, W. B. Campbell, A.-P. Zou, G. J. Gross, and P.-L. Li Characteristics and Superoxide-Induced Activation of Reconstituted Myocardial Mitochondrial ATP-Sensitive Potassium Channels Circ. Res., December 7, 2001; 89(12): 1177 - 1183. [Abstract] [Full Text] [PDF]