Small-conductance Ca2+-dependent K+ channels activated by ATP in murine colonic smooth muscle

被引:89
作者
Koh, SD [1 ]
Dick, GM [1 ]
Sanders, KM [1 ]
机构
[1] Univ Nevada, Sch Med, Dept Physiol & Cell Biol, Reno, NV 89557 USA
来源
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY | 1997年 / 273卷 / 06期
关键词
ion channels; apamin; caffeine; purinergic receptors; enteric inhibitory neurotransmission; gastrointestinal motility;
D O I
10.1152/ajpcell.1997.273.6.C2010
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
The patch-clamp technique was used to determine the ionic conductances activated by ATP in murine colonic smooth muscle cells. Extracellular ATP,UTP, and 2-methylthioadenosine 5'-triphosphate (2-MeS-ATP) increased outward currents in cells with amphotericin B-perforated patches. ATP (0.5-1 mM) did not affect whole cell currents of cells dialyzed with solutions containing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. Apamin(3 x 10(-7) M) reduced the outward current activated by ATP by 32 +/- 5%. Single channel recordings from cell-attached patches showed that ATP, UTP, and 2-MeS-ATP increased the open probability df small-conductance, Ca2+-dependent K+ channels with a slope conductance of 5.3 +/- 0.02 pS. Caffeine (500 mu M) enhanced the open probability of the small-conductance K+ channels, and ATP had no effect after caffeine. Pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid tetrasodium (PPADS, 10(-4) M), a nonselective P-2 receptor antagonist, prevented the increase in open probability caused by ATP and 2-MeS-ATP. PPADS had no effect on the response to caffeine. ATP-induced hyperpolarization in the murine colon may be mediated by P-2y-induced release of Ca2+ from intracellular stores and activation of the 5.3-pS Ca2+-activated K+ channels.
引用
收藏
页码:C2010 / C2021
页数:12
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