The Characterization of the Increase of Membrane Conductance after Depolarization in Single Rat Adrenal Chromaffin Cells

The Characterization of the Increase of Membrane Conductance after Depolarization in Single Rat Adrenal Chromaffin Cells

The conductance change evoked by step depo1arization was studied in primari1y cu1tured rat adrena1 chromaffin cells using patch-c1amp and capacitance measurement techniques. When we applied a depo1arizing pu1se to a chromaffin cell， the inward ca1cium current was followed by an outward current and depo1arization-induced exocytosis was accompanied by an increase in conductance trace. The slow inward tai1 current which has the same time course as the conductance change was observed in current recording. The activation of slow tai1 current was calcium-dependent. Reversa1 potentia1s agreed with Nemst equation assuming re1ative permeability of Cs十 to K十 is 0.095. The outward current and tail current were b10cked by apamin (200 t바.f) and d-tubocurarine (2 mM). The conductance change was b10cked by apamin and did not affect membrane capacitance recording. We confirmed that conductance change after depo1arization comes from the activation of the SK channe1 and can be b10cked by app1ication of the SK channe1 b1ockers. Consequent1y， it is necessary to consider b10cking of the SK channe1 during membrane capacitance recording.