Effects of Temperature on Membrane in Sheep Heart Pubkinje Fibers Currents

Influences of temperature (32℃-38℃） on membrane currents of sheep heart purkinje fiber were examined by means of voltage clamp technique which was done by double microelectrode impalement into a a short strip of the fiber. A slowly decreasing inward current following to an initial rapid inward current was observed in Na-Tyrode solution when the membrane potential was held between-20mV and -40mV. In Na-free solution (Choline-Tyrode), only outward current which gradually decays with the progress of time was observed in depolarizing clamp. The time course of slow inward current is shrtiened in high temperature, but not much prolonged in low temperature. The time course of outward current is prolonged in low temperature but a little shortened in high temperature is mainly caused by the early disappearance of slow inward current carried by Na+ and the prolongation is mainly coused by the slow decay of the outward current carried by K+.

voltage clamp

slow inward current

voltage-current relationship

plateau phase Ca++