Calcium transients in normal and denervated slow muscle fibres of the frog

The Journal of Physiology
R MilediG Schalow

Abstract

1. Intracellular changes in free Ca2+ concentration were recorded from slow muscle fibres in the pyriformis muscle of Rana temporaria, using the dye arsenazo III. Fibres were voltage clamped, and arsenazo signals were recorded in response to depolarizing pulses. 2. The size of the arsenazo response to depolarizing pulses of 100 msec duration was a sigmoid function of membrane potential over the range -45 to 0 mV, and remained constant with further depolarizations up to +100 mV. 3. The peak size of the arsenazo signal to supramaximal depolarizations increased with increasing pulse length. The initial rising phase during a pulse was much slower than in twitch fibres, and this phase was followed by an even slower rise. Following short pulses the decay of the response was exponential, with a time constant of about 1.4 sec, while after long pulses the decline became much slower. 4. Decreasing free Ca2+ concentration in the bathing medium to very low levels, using EGTA , did not affect the responses to short (100 msec) depolarizations. 5. Slow fibres bathed in Ringer's solution containing 12 mM-Ca2+ showed a well maintained arsenazo response to supramaximal depolarizations lasting over 1 min. Reduction of external Ca2+ to 1.8 and (no...Continue Reading

Citations

Apr 1, 1991·Pflügers Archiv : European journal of physiology·O Delbono, B A Kotsias
Aug 1, 1986·Journal of Muscle Research and Cell Motility·A J Avila-SakarE Stefani
Jan 1, 1997·The American Journal of Physiology·M HuertaC Vásquez
Sep 1, 1988·Pflügers Archiv : European journal of physiology·H SchmidtP Krippeit-Drews
May 1, 1983·Pflügers Archiv : European journal of physiology·D G Stephenson, D A Williams
Dec 1, 1989·The Journal of Membrane Biology·P Krippeit-Drews, H Schmidt
Jan 1, 1985·Progress in Biophysics and Molecular Biology·J CailléO Rougier
Jan 1, 1982·Progress in Biophysics and Molecular Biology·J R BlinksF G Prendergast
May 31, 1989·Biochimica Et Biophysica Acta·A Martonosi

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