抄録
Ionic currents in excitation and effects of acetylcholine on them were examined with isolated young calf Purkinje fibers by means of the voltage clamp technique. It was found that in the control state the gNa, which increased markedly at the beginning of depolarization, decreased rapidly until about 50msec and thereafter slowly. The gK, which showed a marked decrease at the beginning of depolarization, showed a fairly rapid increase until 100msec and a gradual increase thereafter.
Acetylcholine showed no significant effects on the ionic current up to the concentration of 10-6g/ml. In a concentration higher than 10-5g/ml the gK decreased soon after the addition of acetylcholine, but increased later. The gNa increased during the first phase of depolarization up to about 150msec, but beyond this phase it decreased progressively.
