Mallart A
J Physiol. 1985 Nov;368:577-91. doi: 10.1113/jphysiol.1985.sp015877.
Local circuit currents involving presynaptic terminals were recorded by micro-electrodes inserted into the perineurium of nerves from the triangularis sterni muscle of the mouse. A transient outward current component was isolated by blocking the voltage-activated (delayed rectifier) K current by 3,4-diaminopyridine (3,4-DAP). The amplitude of this component depended on external K concentration and fell to zero at [K]o = 15 mM. Since it also depended on [Ca]o, it was identified as a Ca-activated K current (IK(Ca)). Tetraethylammonium (TEA) (2 mM), Ba (2 mM), Co (10 mM) and Mn (2.5 mM) blocked IK(Ca). IK(Ca) decayed to zero in approximately 12 ms and recovered from inactivation in about 100 ms. Ca current was enhanced in inverse proportion to the degree of IK(Ca) depression. The possible role of IK(Ca) in the process of neuromuscular facilitation is briefly discussed.
通过插入小鼠胸骨三角肌神经束膜的微电极记录涉及突触前终末的局部回路电流。通过用3,4 - 二氨基吡啶(3,4 - DAP)阻断电压激活(延迟整流)钾电流来分离出一个瞬时外向电流成分。该成分的幅度取决于细胞外钾浓度,在[K]o = 15 mM时降至零。由于它也取决于[Ca]o,所以被鉴定为钙激活钾电流(IK(Ca))。四乙铵(TEA)(2 mM)、钡(2 mM)、钴(10 mM)和锰(2.5 mM)阻断IK(Ca)。IK(Ca)在约12毫秒内衰减至零,并在约100毫秒内从失活状态恢复。钙电流的增强与IK(Ca)抑制程度成反比。简要讨论了IK(Ca)在神经肌肉易化过程中的可能作用。