Voltage-gated and calcium-gated calcium release during depolarization of skeletal muscle fibers

V. Jacquemond, L. Csernoch, M. G. Klein, M. F. Schneider

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Abstract

The role of elevated intracellular calcium concentration ([Ca2+]) in activating calcium release from the sarcoplasmic reticulum (SR) was studied in skeletal muscle fibers microinjected with strong calcium buffers. After the injection of 3.8 +/- 0.5 mM (mean +/- S.E. of mean, n = 16) BAPTA (1,2-bis[o-aminophenoxy]ethane- N,N,N',N'-tetraacetic acid) or 2.2–2.8 mM fura-2 the normal increase in [Ca2+] during a depolarizing pulse was virtually eliminated. Even though calcium was released from the SR the kinetics of this release were markedly altered: the extensive buffering selectively eliminated the early peak component of SR calcium release with no effect on the maintained steady level. Microinjections of similar volumes but with low concentrations of fura-2 had no significant effect on the release waveform. The calcium released by voltage-dependent activation during depolarization may thus be involved in activating further calcium release, that is, in a calcium-induced calcium release mechanism.

Original languageEnglish
Pages (from-to)867-873
Number of pages7
JournalBiophysical journal
Volume60
Issue number4
DOIs
Publication statusPublished - Jan 1 1991

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ASJC Scopus subject areas

  • Biophysics

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