Voltage-dependent charge movement in frog slow muscle fibres

The Journal of Physiology
W F Gilly, C S Hui

Abstract

1. Voltage-clamp experiments on frog slow and twitch fibres were carried out using the three-micro-electrode technique. Potassium currents were blocked by tetraethylammonium. Contraction was blocked by 2 mM-tetracaine. 2. After subtracting the linear capacitive and leakage currents, the delta V(test-control) traces from slow fibres show 'on' and 'off' charge movements similar to those observed in twitch fibres. 3. The time integrals of the 'on' and 'off' transients, Qon and Qoff, in slow fibres are, as in twitch fibres, almost equal in magnitude but opposite in direction. 4. The charge-voltage distribution is well fitted by a sigmoid curve given by (Formula: see text), which has been successfully applied to twitch fibres. Data from three fibres gave V = -25 mV, k = 13 mV, and Qmax = 7 nC/microF. Thus, intramembranous charge in slow fibres has the same steady-state voltage distribution as that in twitch fibres, but the quantity of maximum movable charge is only 1/4 to 1/3 as large. 5. Charge movement in slow fibres does not inactivate completely when the fibres are held at -20 to 0 mV for durations as long as 30 min. 6. These results show that charge movement exists in slow fibres and may serve the same function in regulating co...Continue Reading

Citations

Dec 1, 1989·The Journal of Membrane Biology·P Krippeit-Drews, H Schmidt
Jan 1, 1982·The Journal of Membrane Biology·H Miyamoto, E Racker
Nov 1, 1989·Pflügers Archiv : European journal of physiology·Y MounierL Stevens
Jan 1, 1985·Progress in Biophysics and Molecular Biology·J CailléO Rougier
Sep 1, 1988·Pflügers Archiv : European journal of physiology·H SchmidtP Krippeit-Drews
Sep 1, 1982·Journal of Muscle Research and Cell Motility·F MascarelloE Jenny
Jun 1, 1987·Journal of Muscle Research and Cell Motility·C S Hui, R L Milton
Jan 1, 1984·The American Journal of Physiology·R E GodtA M Gordon
May 8, 1995·Biochimica Et Biophysica Acta·W MelzerH C Lüttgau

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