抄録
Gating kinetics of the Ca channel have been studied recently by applying a cell attached patch clamp and a whole cell recording techniques to the rat pituitary cell line, GH3, and to the hair cells dissociated from a chick vestibular organ. In both preparations, Ca channels were gated open by depolarizing command pulses and were not inactivated. The activation kinetics were reasonably fitted by the mm2 kinetic model, while the steady-state noise analysis indicated a presence of much faster opening-closing kinetics in the gating mechanism. The fast opening-closing gating mechanism was observed in the Ba cullents passing through a single Ca channel. Steady-state noise analyses and single channel Ba currents suggest a presence of dual gates in the Ca channel; the one may be a voltage dependent slow gate which operates on a reaction scheme analogous to the mm2 process, and the other may be a less voltage dependent fast gate which seems operating independent of the slow gate.
