HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Szentesi, P. Articles by Csernoch, L. Search for Related Content PubMed PubMed Citation Articles by Szentesi, P. Articles by Csernoch, L.

Deterministic inactivation of calcium release channels in mammalian skeletal muscle

Péter Szentesi, László Kovács and László Csernoch

1. Enzymatically dissociated fibres from the extensor digitorum communis muscle of rats were mounted into a double Vaseline gap chamber. The rate of calcium release (R_rel) from the sarcoplasmic reticulum (SR) and changes in SR permeability to Ca²⁺ (P_SR) were calculated from measured changes in intracellular calcium concentration.

2. Calcium release during a prepulse attenuated the inactivating component of P_SR of the subsequent test pulse. The suppression was graded, larger release causing greater suppression, as expected from a calcium-dependent inactivation process. However, if the dissociation constant of the putative inhibitory calcium binding site (K_d) was estimated using different test pulses different affinities were obtained: a smaller test pulse yielded a smaller K_d.

3. Comparing the suppression of the inactivatable component of P_SR during the test pulse (suppression) with the inactivatable component during the prepulse (pre-inactivation) revealed a linear relationship with a regression coefficient close to unity.

4. Lowering intracellular magnesium by decreasing its concentration to 25 µM in the internal solution altered the time course of P_SR. The maximal peak-to-steady-level ratio was increased to 6·3 ± 0·4 (n = 10, mean ± s.e.m.) from a control value of 3·0 ± 0·2 (n = 19). Despite the apparent change in steady-state inactivation, suppression remained equal to that pre-inactivation.

5. Our results support the view that a depolarizing pulse always recruits the same set of calcium release channels and a portion of these channels undergoes a deterministic inactivation process.

This article has been cited by other articles:

				R. Jimenez-Moreno, Z.-M. Wang, R. C. Gerring, and O. Delbono Sarcoplasmic Reticulum Ca2+ Release Declines in Muscle Fibers from Aging Mice Biophys. J., April 15, 2008; 94(8): 3178 - 3188. [Abstract] [Full Text] [PDF]

				S. Pouvreau, B. Allard, C. Berthier, and V. Jacquemond Control of intracellular calcium in the presence of nitric oxide donors in isolated skeletal muscle fibres from mouse J. Physiol., November 1, 2004; 560(3): 779 - 794. [Abstract] [Full Text] [PDF]

				P. Szentesi, H. Szappanos, C. Szegedi, M. Gonczi, I. Jona, J. Cseri, L. Kovacs, and L. Csernoch Altered Elementary Calcium Release Events and Enhanced Calcium Release by Thymol in Rat Skeletal Muscle Biophys. J., March 1, 2004; 86(3): 1436 - 1453. [Abstract] [Full Text] [PDF]

				R.P. Schuhmeier and W. Melzer Voltage-dependent Ca2+ Fluxes in Skeletal Myotubes Determined Using a Removal Model Analysis J. Gen. Physiol., December 29, 2003; 123(1): 33 - 52. [Abstract] [Full Text] [PDF]

				G. D. Lamb, G. S. Posterino, T. Yamamoto, and N. Ikemoto Effects of a domain peptide of the ryanodine receptor on Ca2+ release in skinned skeletal muscle fibers Am J Physiol Cell Physiol, July 1, 2001; 281(1): C207 - C214. [Abstract] [Full Text] [PDF]