Stretch-activation of rat cardiac myocytes

Mechanically activated ion channels (MACs) in rat ventricular myocytes were activated by stretching membrane patches attached to microelectrodes. Charge injection from MACs, consisting mainly of inward K+, was sometimes of sufficient magnitude (0.2 pC) during brief (50 ms) periods, to trigger action currents. Action currents were shown to be extracellular records of action potentials. These results demonstrate the activation of myocytes by injection of approximately 4 pA from a few MACs in a membrane patch.