Participation of Ca2(+)-activated K+ channels in electrical activity of canine gastric smooth muscle

The Journal of Physiology
A CarlK M Sanders

Abstract

1. The hypothesis that Ca2(+)-activated K+ channels participate in the repolarization of electrical slow waves was tested in isolated cells and intact muscles of the canine gastric antrum. 2. Freshly dispersed cells from the gastric antrum liberally express large conductance channels that were characterized as Ca2(+)-activated K+ channels by several criteria. 3. Mean slope conductance of these channels in symmetrical 140 mM-KCl solutions was 265 +/- 25 pS and reversal potential was 1.3 +/- 3.3 mV. The reversal potential was shifted when K+ was partially replaced with Na+ in a manner consistent with the Nernst equation for the K+ gradient. 4. Open probability was studied in excised patches in solutions containing 10(-7)-10(-6) M-Ca2+ with holding potentials ranging from -100 to +100 mV. Resulting activation curves were fitted by Boltzmann functions. 5. Increasing [Ca2+] from 10(-7) to 10(-6) M shifted the half-maximal activation from +99 to 0 mV. These data suggest that Ca2(+)-activated K+ channels may be activated in the voltage range and [Ca2+]i occurring during the plateau phase of the slow wave. 6. In intact muscles loaded with the photolabile Ca2+ chelator, nitr-5, photo-activated release of Ca2+ during the slow wave cycle ...Continue Reading

Citations

Feb 1, 1996·Biological cybernetics·R N MiftakhovD L Wingate
Aug 30, 2008·The Journal of Physiology·Minkyung KimBrian A Perrino
Apr 10, 2007·Archives of Medical Research·Israel GrijalvaJosé Antonio Palma-Aguirre
May 1, 1992·Pflügers Archiv : European journal of physiology·A CarlJ R Hume
Jun 23, 2009·Journal of Korean Medical Science·Young Chul KimSang Jin Lee
Apr 13, 1999·The American Journal of Physiology·B R HurleyS M Sims
May 1, 1994·The American Journal of Physiology·S C Sansom, J D Stockand
May 1, 1991·The American Journal of Physiology·F VogalisK M Sanders
Oct 1, 1993·Pharmacology & Therapeutics·F De PontiG Frigo

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