Modification of the Voltage Dependent Na^+ Conductance by External pH in the Dinoflagellate Noctiluca miliaris

概要

論文の詳細を見る
Effects of the external pH on the voltage-dependent Na conductance in the marine dinoflagellate Noctiluca miliaris were examined under voltage-clamp conditions. The depolarizing Na spike (positive spike) in the tentacle regulating potentials became attenuated when the external pH was lowered from 8 (normal value) to less than 5. Under voltage-clamp conditions, a depolarization-activated transient inward current corresponding to the positive spike decreased with lowering the external pH to less than 5, and entirely disappeared at pH 3. Threshold for the inward current shifted towards the depolarizing direction while the reversal potential of the current shifted towards the hyperpolarizing direction with lowering the external pH. Rate of increase in the inward current reduced whereas rate of decrease did not change at low pH. Lowering of the external pH did not affect the steady state inactivation of the inward current. It is concluded that the external pH controls appearance of the positive spike through modification of activation kinetics and selectivity of the voltage-dependent Na conductance responsible for the spike.
社団法人日本動物学会の論文
1996-12-15