Voltage clamp experiments in adult rat single ventricular myocytes demonstrated an early outward transient potassium current that was blocked by 4-aminopyridine and Bao.
Voltage clamp experiments were conducted using single ventricular myocytes which had been dissociated enzymatically from adult rat hearts in order to examine further the membrane currents which contribute to the unusual plateau of the rat action potential. Membrane currents were recorded, using a single microelectrode (switching) voltage clamp circuit. From holding potentials near the resting potential (-80 to -90 mV), depolarizing clamp steps above -20 mV elicited an early outward current which overlapped in time with the slow inward current and displayed time-dependent inactivation. This is the first demonstration of a transient potassium current in an isolated ventricular myocyte. The early outward potential was voltage-inactivated at holding potentials of -50 to -40 mV and was blocked by 4-aminopyridine. The current was not dependent on Cao or ICa and was blocked by Bao. Double pulse experiments revealed that the time course for the recovery of the early outward current at -80 mV was rapid, and had a tau of 25 msec. The possible functional significance of this current is discussed.
Josephson et al. (Wed,) conducted a other in Normal physiology (rat ventricular myocytes). Voltage clamp experiments was evaluated on Membrane currents contributing to the plateau of the rat action potential. Voltage clamp experiments in adult rat single ventricular myocytes demonstrated an early outward transient potassium current that was blocked by 4-aminopyridine and Bao.
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