UNIQUE AFTER-HYPERPOLARIZATION ACCOMPANYING ACTION-POTENTIAL IN CHARA-GLOBULARIS

A unique after-hyperpolarization was found in internodal cells of Char a globularis. The cells generated an ordinary action potential due to regenerative depolarization induced by the outward electric current pu lse larger than a threshold stimulus. After reaching a depolarizing pe ak, the membrane potential repolarized and overshooted the resting pot ential to a value which was somehow 40 mV more negative than the resti ng potential before stimulation (after-hyperpolarization). Since the m embrane resistance increased during the after-hyperpolarization, the a fter-hyperpolarization is thought to be caused by an increase in the r esistance (decrease in the conductance) of the passive diffusion chann el.