Abstract
Effects of TEA on the configulation of action potential of cardiac muscle in Rana catesibiana and Bufo vulgaris was studied, using the suction electrode which was devised by Ozawa. Ozawa's suction electrode has been proved that it can record the monophasic action potential as exact as intracellular electrode. TEA-Ringer solution was prepared replacing Na+in Ringer by isotonic TEA. And in need, hypertonic TEA-Ringer was used, adding sucrose into TEA-Ringer solution. TEA had no effect on rising rate of action potential of ventricle and atrium, however its amplitude was remarkablly enhanced and plateau was prolonged. Enhancement of amplitude is caused by TEA which is considered to accelerate -the influx of Ca++. And prolongation of plateau is caused by K+eflux inhibiting action of TEA.
Enhancement of amplitude of action potential reached to its maximum 15-20 minutes after bathing the cardiac muscle in TEA-Ringer, and thereafter it diminished gradually, but the prolongation of duration of action potential continued for long time.
In later stage of TEA action, the action potential was separated into spike and slow potential. Separation of action potential is considered as inhibiting action of TEA of Ca++influx. TEA action is considered dual way, i.e. at first acceleration and then inhibition on Ca++ influx.
In TEA-Ringer solution, cardiac muscle strip react to single shock with repetative responses, which repeat more than hundred times.
In hypertonic TEA-Ringer solution, action potential was separated in spike and slow rcomponent and the latter was exceedingly reduced. Spike component was divided into several spikes and end of slow component showed oscilations.
