Immobilization of membrane charge in frog skeletal muscle by prolonged depolarization

The Journal of Physiology
R F Rakowski

Abstract

1. Inactivation ('immobilization') of the non-linear component of capacitive current in semitendinosus muscles of Rana pipiens was studied using the three-micro-electrode voltage-clamp technique (Adrian, Chandler & Hodgkin, 1970). 2. The steady-state voltage dependence of non-linear charge immobilization was determined by changing the holding potential. The data were fitted to an equation analogous to that used to describe the charge activation process (Schneider & Chandler, 1973). The steepness parameter, k, is the same for charge activation and immobilization, but the mid-point voltage of charge immobilization is 8.9 +/- 2.6 mV (n = 9) more negative than the mid-point of the non-linear charge activation curve. The charge relaxation rate constants are unaffected by changes in holding potential. 3. The time course of non-linear charge immobilization was studied using a protocol that measures the change in capacitive current required for a voltage step of a fixed magnitude determined before and after an intervening period of depolarization. The sum of the non-linear charge that is immobilized and the non-linear charge that remains mobile after a prolonged (greater than 1 s) depolarization is equal to the total non-linear charge ...Continue Reading

Citations

Jan 1, 1992·Progress in Biophysics and Molecular Biology·A F Dulhunty
Jan 1, 1985·Progress in Biophysics and Molecular Biology·J CailléO Rougier
Jan 24, 2002·The Journal of Pharmacology and Experimental Therapeutics·Wissam H JoumaaClaude Léoty
Aug 1, 1985·Journal of Muscle Research and Cell Motility·R F RakowskiM R James-Kracke

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