Mechanical activation in slow and twitch skeletal muscle fibres of the frog

The Journal of Physiology
W F Gilly, C S Hui

Abstract

1. Slow and twitch muscle fibres of the frog were studied with a two-micro-electrode point voltage-clamp method. Slow fibres were identified in pyriformis and cruralis muscles by their appearance in the light microscope, electrical characteristics, and rate of sarcomere shortening or of tension development. 2. The relation between the amplitude and duration of threshold depolarizing pulses was determined in sartorius twitch and pyriformis slow fibres. Strength-duration relations for contractile activation are very similar in the two fibre types. 3. The effect of a brief subthreshold pulse on the threshold voltage level decays with a half-time of 1-2 msec at 9 degrees C in both slow and twitch fibres. This fast decay, thought to reflect voltage-dependent deactivation of Ca2+ release following repolarization, is followed by a slower decay of greatly different rates in the two fibre types. the slower components of decay might reflect the rate of background Ca2+ removal by the sarcoplasmic reticulum. 4. Reducing external Ca2+ levels to about about 0.1 microM with 2.5 mM-EGTA has no effect on the shapes of strength-duration curves for both slow and twitch fibres, suggesting that activator Ca2+ in both fibre types originates entirely...Continue Reading

Citations

Jun 5, 2003·Experimental Neurology·Miguel HuertaBenjamin Trujillo-Hernández
Nov 1, 1989·Pflügers Archiv : European journal of physiology·Y MounierL Stevens
Jan 1, 1985·Progress in Biophysics and Molecular Biology·J CailléO Rougier
Nov 13, 2013·The Journal of Membrane Biology·Xóchitl TrujilloMiguel Huerta
Sep 1, 1988·Pflügers Archiv : European journal of physiology·H SchmidtP Krippeit-Drews
Jan 1, 1990·Journal of Neurobiology·A A Herrera, M J Werle
Oct 13, 2018·The Anatomical Record : Advances in Integrative Anatomy and Evolutionary Biology·Nosta GlaserClara Franzini-Armstrong
Nov 13, 2013·Physiological Measurement·Namrata GundiahLisa A Pruitt
Oct 1, 1987·Journal of Muscle Research and Cell Motility·C Franzini-ArmstrongD Appelt

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