Abstract
The spatiotemporal distribution of intracellular Ca(2+) release in contracting skeletal and cardiac muscle cells was defined using a snapshot imaging technique. Calcium imaging was performed on intact skeletal and cardiac muscle cells during contractions induced by an action potential (AP). The sarcomere length of the skeletal and cardiac cells was approximately 2 micrometer. Imaging Rhod-2 fluorescence only during a very brief (7 ns) snapshot of excitation light minimized potential image-blurring artifacts due to movement and/or diffusion. In skeletal muscle cells, the AP triggered a large fast Ca(2+) transient that peaked in less than 3 ms. Distinct subsarcomeric Ca(2+) gradients were evident during the first 4 ms of the skeletal Ca(2+) transient. In cardiac muscle, the AP-triggered Ca(2+) transient was much slower and peaked in approximately 100 ms. In contrast to the skeletal case, there were no detectable subsarcomeric Ca(2+) gradients during the cardiac Ca(2+) transient. Theoretical simulations suggest that the subsarcomeric Ca(2+) gradients seen in skeletal muscle were detectable because of the high speed and synchrony of local Ca(2+) release. Slower asynchronous recruitment of local Ca(2+) release units may account for the absence of detectable subsarcomeric Ca(2+) gradients in cardiac muscle. The speed and synchrony of local Ca(2+) gradients are quite different in AP-activated contracting cardiac and skeletal muscle cells at normal resting sarcomere lengths.
Full Text
The Full Text of this article is available as a PDF (1.3 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Armstrong C. M., Bezanilla F. M., Horowicz P. Twitches in the presence of ethylene glycol bis( -aminoethyl ether)-N,N'-tetracetic acid. Biochim Biophys Acta. 1972 Jun 23;267(3):605–608. doi: 10.1016/0005-2728(72)90194-6. [DOI] [PubMed] [Google Scholar]
- Beeler G. W., Jr, Reuter H. The relation between membrane potential, membrane currents and activation of contraction in ventricular myocardial fibres. J Physiol. 1970 Mar;207(1):211–229. doi: 10.1113/jphysiol.1970.sp009057. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Beuckelmann D. J., Wier W. G. Mechanism of release of calcium from sarcoplasmic reticulum of guinea-pig cardiac cells. J Physiol. 1988 Nov;405:233–255. doi: 10.1113/jphysiol.1988.sp017331. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cannell M. B., Allen D. G. Model of calcium movements during activation in the sarcomere of frog skeletal muscle. Biophys J. 1984 May;45(5):913–925. doi: 10.1016/S0006-3495(84)84238-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Caputo C., Bolaños P., Escobar A. L. Fast calcium removal during single twitches in amphibian skeletal muscle fibres. J Muscle Res Cell Motil. 1999 Aug;20(5-6):555–567. doi: 10.1023/a:1005526202747. [DOI] [PubMed] [Google Scholar]
- Caputo C. The role of calcium in the processes of excitation and contraction in skeletal muscle. J Gen Physiol. 1968 May;51(5 Suppl):180S+–180S+. [PubMed] [Google Scholar]
- Cheng H., Lederer W. J., Cannell M. B. Calcium sparks: elementary events underlying excitation-contraction coupling in heart muscle. Science. 1993 Oct 29;262(5134):740–744. doi: 10.1126/science.8235594. [DOI] [PubMed] [Google Scholar]
- Cleemann L., Wang W., Morad M. Two-dimensional confocal images of organization, density, and gating of focal Ca2+ release sites in rat cardiac myocytes. Proc Natl Acad Sci U S A. 1998 Sep 1;95(18):10984–10989. doi: 10.1073/pnas.95.18.10984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Escobar A. L., Monck J. R., Fernandez J. M., Vergara J. L. Localization of the site of Ca2+ release at the level of a single sarcomere in skeletal muscle fibres. Nature. 1994 Feb 24;367(6465):739–741. doi: 10.1038/367739a0. [DOI] [PubMed] [Google Scholar]
- Fabiato A. Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum. Am J Physiol. 1983 Jul;245(1):C1–14. doi: 10.1152/ajpcell.1983.245.1.C1. [DOI] [PubMed] [Google Scholar]
- Györke S., Vélez P., Suárez-Isla B., Fill M. Activation of single cardiac and skeletal ryanodine receptor channels by flash photolysis of caged Ca2+. Biophys J. 1994 Jun;66(6):1879–1886. doi: 10.1016/S0006-3495(94)80981-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hille B., Campbell D. T. An improved vaseline gap voltage clamp for skeletal muscle fibers. J Gen Physiol. 1976 Mar;67(3):265–293. doi: 10.1085/jgp.67.3.265. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Isenberg G., Etter E. F., Wendt-Gallitelli M. F., Schiefer A., Carrington W. A., Tuft R. A., Fay F. S. Intrasarcomere [Ca2+] gradients in ventricular myocytes revealed by high speed digital imaging microscopy. Proc Natl Acad Sci U S A. 1996 May 28;93(11):5413–5418. doi: 10.1073/pnas.93.11.5413. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kovács L., Ríos E., Schneider M. F. Calcium transients and intramembrane charge movement in skeletal muscle fibres. Nature. 1979 May 31;279(5712):391–396. doi: 10.1038/279391a0. [DOI] [PubMed] [Google Scholar]
- Miledi R., Parker I., Schalow G. Measurement of calcium transients in frog muscle by the use of arsenazo III. Proc R Soc Lond B Biol Sci. 1977 Aug 22;198(1131):201–210. doi: 10.1098/rspb.1977.0094. [DOI] [PubMed] [Google Scholar]
- Mitra R., Morad M. A uniform enzymatic method for dissociation of myocytes from hearts and stomachs of vertebrates. Am J Physiol. 1985 Nov;249(5 Pt 2):H1056–H1060. doi: 10.1152/ajpheart.1985.249.5.H1056. [DOI] [PubMed] [Google Scholar]
- Monck J. R., Robinson I. M., Escobar A. L., Vergara J. L., Fernandez J. M. Pulsed laser imaging of rapid Ca2+ gradients in excitable cells. Biophys J. 1994 Aug;67(2):505–514. doi: 10.1016/S0006-3495(94)80554-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Näbauer M., Callewaert G., Cleemann L., Morad M. Regulation of calcium release is gated by calcium current, not gating charge, in cardiac myocytes. Science. 1989 May 19;244(4906):800–803. doi: 10.1126/science.2543067. [DOI] [PubMed] [Google Scholar]
- Pizarro G., Csernoch L., Uribe I., Rodríguez M., Ríos E. The relationship between Q gamma and Ca release from the sarcoplasmic reticulum in skeletal muscle. J Gen Physiol. 1991 May;97(5):913–947. doi: 10.1085/jgp.97.5.913. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ríos E., Pizarro G. Voltage sensor of excitation-contraction coupling in skeletal muscle. Physiol Rev. 1991 Jul;71(3):849–908. doi: 10.1152/physrev.1991.71.3.849. [DOI] [PubMed] [Google Scholar]
- Sandow A. Excitation-contraction coupling in skeletal muscle. Pharmacol Rev. 1965 Sep;17(3):265–320. [PubMed] [Google Scholar]
- Schneider M. F., Chandler W. K. Voltage dependent charge movement of skeletal muscle: a possible step in excitation-contraction coupling. Nature. 1973 Mar 23;242(5395):244–246. doi: 10.1038/242244a0. [DOI] [PubMed] [Google Scholar]
- Shirokova N., García J., Pizarro G., Ríos E. Ca2+ release from the sarcoplasmic reticulum compared in amphibian and mammalian skeletal muscle. J Gen Physiol. 1996 Jan;107(1):1–18. doi: 10.1085/jgp.107.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Soeller C., Cannell M. B. Examination of the transverse tubular system in living cardiac rat myocytes by 2-photon microscopy and digital image-processing techniques. Circ Res. 1999 Feb 19;84(3):266–275. doi: 10.1161/01.res.84.3.266. [DOI] [PubMed] [Google Scholar]
- Tsugorka A., Ríos E., Blatter L. A. Imaging elementary events of calcium release in skeletal muscle cells. Science. 1995 Sep 22;269(5231):1723–1726. doi: 10.1126/science.7569901. [DOI] [PubMed] [Google Scholar]
- Vergara J., Bezanilla F., Salzberg B. M. Nile blue fluorescence signals from cut single muscle fibers under voltage or current clamp conditions. J Gen Physiol. 1978 Dec;72(6):775–800. doi: 10.1085/jgp.72.6.775. [DOI] [PMC free article] [PubMed] [Google Scholar]