caa a22 4500 47574540X CHVBK 20180406123511.0 cr unu---uuuuu 170329e20000201xx s 000 0 eng 10.1023/A:1005630321863 doi (NATIONALLICENCE)springer-10.1023/A:1005630321863 Regulation of the rat sarcoplasmic reticulum calcium release channel by calcium [Elektronische Daten] [Sándor Sárközi, Csaba Szegedi, Péter Szentesi, László Csernoch, László Kovács, István Jóna] The regulation by calcium of the ryanodine receptor/SR calcium release channel (RyR) from rat skeletal muscle was studied under isolated conditions and in situ. RyRs were either solubilized and incorporated into lipid bilayers or single fibres were mounted into a Vaseline gap voltage clamp. Single channel data were compared to parameters determined from the calculated calcium release flux. With K+ (250 mM) being the charge carrier the single channel conductance was 529 pS at 50 μM Ca2+ cis and trans, and decreased with increasing cis [Ca2+]. Open probability showed a bell shaped calcium dependence revealing an activatory and an inhibitory Ca2+ binding site (Hill coefficients of 1.18 and 1.28, respectively) with half activatory and inhibitory concentrations of 9.4 and 298 μM. The parameters of the inhibitory site agreed with the calcium dependence of channel inactivation deduced from the decline in SR calcium release in isolated fibres. Mean open time showed slight [Ca2+] dependence following a single exponential at every Ca2+ concentration tested. Closed time histograms, at high [Ca2+], were fitted with three exponentials, from which the longest was calcium independent, and resembled the recovery time constant of SR inactivation (115 ± 15 ms) obtained in isolated fibres. The data are in agreement with a model where calcium binding to the inhibitory site on RyR would be responsible for the calcium dependent inactivation in situ. Kluwer Academic Publishers, 2000 Sárközi Sándor Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut Szegedi Csaba Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut Szentesi Péter Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut Csernoch László Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut Kovács László Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut Jóna István Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/2(2000-02-01), 131-138 0142-4319 21:2<131 2000 21 10974 https://doi.org/10.1023/A:1005630321863 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1005630321863 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sárközi Sándor Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut NATIONALLICENCE 700 1- Szegedi Csaba Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut NATIONALLICENCE 700 1- Szentesi Péter Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut NATIONALLICENCE 700 1- Csernoch László Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut NATIONALLICENCE 700 1- Kovács László Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut NATIONALLICENCE 700 1- Jóna István Department of Physiology, University Medical School of Debrecen, and Cell Physiology Research Group of Hungarian Academy of Science Hungary, P.O. Box 22, H-4012, Debrecen, Hungary aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/2(2000-02-01), 131-138 0142-4319 21:2<131 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer