Subcellular mechanism for Ca2+-dependent enhancement of delayed rectifier K+ current in isolated membrane patches of Guinea pig ventricular myocytes

Abstract

Intracellular Ca2+ augments delayed rectifier K+ current (IK) in cardiac myocytes, which may play a major modulatory role in repolarization of action potentials. We investigated subcellular mechanisms for Ca2+-induced enhancement of IK in large-pipette inside-out membrane patches excised from isolated guinea pig ventricular myocytes. When [Ca2+]i was raised from 10-8 to 10-6 mol/L, the amplitude of IK measured at +80 mV was increased from 12.0±2.2 to 19.5±3.3 pA (P