Voltage-Gated Membrane Current of Isolated Bullfrog Taste Cells(Physiology)

概要

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The membrane properties of enzymatically isolated bullfrog taste cells were studied using the whole-cell patch-clamp technique. Five voltage-dependent ionic currents were observed in the bullfrog taste cells: a transient tetrodotoxin (TTX)-sensitive Na^+ current; a Ca^<2+>-activated K^+ current; a transient K^+ current; a sustained K^+ current; and an inward rectifier K^+ current. The transient inward Na^+ current, Ca^<2+>-activated and transient outward K^+ currents began to be activated by depolarization to -40 to -20 mV from a holding potential more negative than -60 mV, while a novel transient outward current was activated by voltage steps to the potential more positive than +40 mV from a holding potential of -40 mV in Ca-<2+>-free saline. The sustained current was not inactivated at least 5 min after onset of voltage shift from -60 to -40 mV. We did not find any Ca^<2+> current under the condition of the present experiment. The inward rectifier K^+ current was observed in normal and high K^+ saline, and the amplitude and the reversal potential for the current seemed to change depending upon the external K^+ concentration. These results suggest that the inward currents produced by the inward rectifier K^+ channel as well as other K^+ channels contribute to gustatory transduction of KCl stimuli into the receptor potential if those channels are located in the receptive membrane.
社団法人日本動物学会の論文
1991-10-15