Calcium transients evoked by action potentials in frog twitch muscle fibres

The Journal of Physiology
R MilediP H Zhu

Abstract

1. Intracellular Ca(2+) transients were recorded from frog twitch muscle fibres in response to action potentials and repetitive stimulation, using ionophoretically injected arsenazo III as a Ca(2+) monitor. A dual wave-length optical system was used to measure absorbance changes of the injected dye from small areas of single fibres within the cutaneous pectoris muscle.2. The absorbance spectrum of the injected arsenazo III in a resting fibre was consistent with an intracellular free Mg(2+) level of a few hundred micromolar, assuming an intracellular pH of 7.1. The resting free Ca(2+) concentration was below the limit of resolution.3. The wave-length dependence of the arsenazo light absorbance signal during twitches followed that expected for Ca(2+) binding to the dye. Recordings made at wave-lengths where the dye is maximally sensitive to pH or Mg(2+) concentration changes indicated that interference from these sources is minimal at the usual wave-length pair (650-700 nm) used for Ca(2+) recordings.4. Over a wide range of intracellular dye concentrations, the size of the arsenazo response to an action potential increased linearly with dye concentration (100-1000 muM), although there were deviations from this relationship at low...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
Jul 27, 2011·The Journal of Cell Biology·Basile DarbellayLaurent Bernheim
May 3, 2000·Medical Hypotheses·F González-Aguilar
Oct 22, 1986·Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character·P H ZhuR Miledi
Oct 1, 1994·Pflügers Archiv : European journal of physiology·X F Wang, P H Zhu
Jul 26, 1988·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·A P SomlyoA V Somlyo
Aug 1, 1985·Journal of Muscle Research and Cell Motility·R F RakowskiM R James-Kracke
Oct 1, 1993·Journal of Muscle Research and Cell Motility·M RozyckaW Goldman
Oct 1, 1984·Journal of Muscle Research and Cell Motility·V Lombardi, G Menchetti

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