Rectification of muscarinic K+ current by magnesium ion in guinea pig atrial cells.
Rectification of muscarinic K+ current by magnesium ion in guinea pig atrial cells.
复制标题
豚鼠心房细胞中镁离子对毒蕈碱钾电流的整流。
DOI：
--
复制
发表时间：
1987
影响因子：
--
通讯作者：
H. Irisawa
中科院分区：
文献类型：
--
作者：
M. Horie;H. Irisawa
Rectifying properties of the acetylcholine (ACh)-sensitive K+ channels were studied using a patch-clamp method in single atrial cells prepared enzymatically from adult guinea pig hearts. In the presence of micromolar concentration of nonhydrolyzable guanosine 5'-triphosphate (GTP) analogue 5'-guanylylimidodiphosphate (GppNHp) and the absence of Mg2+ at the inner surface of patch membrane [( Mg2+]i), the channel activity recovered in inside-out patch condition. The single channel conductance became ohmic between -80 and +80 mV (symmetrical 150 mM K+ solutions). The rapid relaxation of outward single channel currents was disclosed on a depolarization. [Mg2+]i blocked the outward current through the channel dose- and voltage-dependently and also induced a dose-dependent increase in the channel activation. The apparent paradoxical role of [Mg2+]i is important for the cholinergic control in the heart; voltage-dependent Mg block ensures a low K+ conductance of cell membrane at the plateau of action potentials during the exposure to ACh, thereby slowing the heart rate without unfavorable shortening of the action potentials.
