Abstract
Using a high resistance ultramicro-electrode, devised by Ling and Gerad, the membrane potential and action potential of smooth muscle cell of ureter from guinea pig were observed by cathode-ray oscilloscope.
The intracellular microelectrode was suspended from the micromaniplator utilizing the method of Woodbury and Brady.
Range of the distribution of the membrane potential was 120 mV-40 mV. The configuration of the action potential is consisted from two components, ie, pure spike potential of oscillatory natur and slow potential, acompanied by long plateau. No difference was observed between the action potential evoked by artificial stimulus and that appeared spontaneously.
Duration of single spike potential was 40 msec and its maximal intensity was about 40 mV.
Oscillatory spike potentials which appear always at the begining part of the slow potential vanished when tetra-ethyl ammonium bromid was applied into the bathing fluid. According to the concentration of TEA, sooner or later the action potential bereft of the oscillating spikes becomes simple long lasting slow wave which seems as if it is an action potential of cardiac muscle, ie, initial rapid depolarization, long plateau followed by gradual repolarization.
