ON MEMBRANE-POTENTIAL AND CILIARY STIMULATION

The relation between membrane potential and ciliary beat frequency was examined in tissue cultures from frog palate and esophagus. It was fo und that hyperpolarization or depolarization of the ciliary cell membr ane enhances ciliary beating. The induced enhancement of the ciliary b eat frequency by either hyperpolarization or depolarization depends on the extracellular Ca2+ concentration, however, the involvement of vol tage-gated calcium channels is unlikely, since blockers of voltage-gat ed channels at their specific concentrations did not have any effect. However, partial inhibition was achieved by a 10-50 fold increase in t he concentration of blockers. Moreover, it was shown that the magnitud e of ciliary activation depends on the method by which depolarization of the cell was achieved. Quinidine (1 mM) abolished ciliary enhanceme nt induced by either hyperpolarization or depolarization. Based on the se findings we conclude that the enhancement of ciliary beating is not controlled solely by the membrane potential. (C) 1997 Elsevier Scienc e S.A.