We used the whole-cell configuration of the patch-clamp technique to investigate modulation of the voltage-dependent K+ conductance of rat Leydig cells by intracellular pH, Hepes, and Na+. pH (range 6.8-7.4) has no effect on current. Removal of Na+ (from 10 to 0 mM) increases the amplitude of K+ current and abolishes the plateau effect on peak current. Reduction of Hepes (from 25 to 10 mM) increases the amplitude of K+ current and, simultaneously, shifts the threshold for current activation to the left, but the plateau of current is still present. Removal of Na+ cancels the potentiating effect of Hepes on frequency of occurrence of time-dependent inactivation of K+ current. We conclude that the blocking effect of Hepes and Na+ on K+ current may presumably involve two distinct mechanisms, but we can not exclude some cooperativity in their ability to inactivate the voltage-gated potassium conductance of rat Leydig cells

Inhibitory effect of internal sodium and Hepes on the voltage-dependent potassium conductance of rat Leydig cells

DESAPHY, Jean Francois;
1996-01-01

Abstract

We used the whole-cell configuration of the patch-clamp technique to investigate modulation of the voltage-dependent K+ conductance of rat Leydig cells by intracellular pH, Hepes, and Na+. pH (range 6.8-7.4) has no effect on current. Removal of Na+ (from 10 to 0 mM) increases the amplitude of K+ current and abolishes the plateau effect on peak current. Reduction of Hepes (from 25 to 10 mM) increases the amplitude of K+ current and, simultaneously, shifts the threshold for current activation to the left, but the plateau of current is still present. Removal of Na+ cancels the potentiating effect of Hepes on frequency of occurrence of time-dependent inactivation of K+ current. We conclude that the blocking effect of Hepes and Na+ on K+ current may presumably involve two distinct mechanisms, but we can not exclude some cooperativity in their ability to inactivate the voltage-gated potassium conductance of rat Leydig cells
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11586/3819
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