Voltage control during inward current flow in rat ventricular muscle using a double sucrose gap technique.

In rat ventricular muscle, measurements of the membrane potential with microelectrodes during depolarizing voltage steps showed that deviation of the membrane potential from the command signal were never larger than 15 mV during flow of the fast inward current and that voltage control was regained within 15 ms after the beginning of the voltage step. During the flow of the slow inward current, tail currents elicited by interrupting the time course of the slow current at different time intervals returned exponentially to the steady-state level, thus indicating acceptable voltage control. It is concluded that rat ventricular muscle is a rather favorable preparation for voltage-clapm experiments and this is attributed mainly to the geometry of the preparation.