Partial depletion of sarcoplasmic reticulum calcium does not prevent calcium sparks in rat ventricular myocytes - PubMed (original) (raw)
Partial depletion of sarcoplasmic reticulum calcium does not prevent calcium sparks in rat ventricular myocytes
L S Song et al. J Physiol. 1997.
Abstract
1. The exact nature of calcium sparks in the heart remains highly controversial. We sought to determine whether calcium sparks arise from a single or multiple calcium release channels/ ryanodine receptors in the sarcoplasmic reticulum (SR). If their genesis involves a calcium-coupled recruitment of multiple channels, calcium sparks might be abolished by a modest depletion of SR calcium (because of the decrease in unitary calcium flux and hence a decrease in the gain of local calcium-induced calcium release). If, on the other extreme, calcium sparks are produced despite severe SR depletion, the single-channel origin will be preferred. 2. Spontaneous calcium sparks were studied in rat ventricular myocytes using confocal microscopy and the fluorescent calcium probe fluo-3. A computer algorithm was developed to count and measure objectively calcium sparks in linescan images. 3. Thapsigargin (25-150 nM) depleted caffeine-releasable SR calcium by up to 64%, in a dose- and time-dependent manner, without altering the resting cytosolic calcium level. During SR depletion, calcium sparks were robustly observed, albeit at reduced frequency (> or = 30% of control) and amplitude (> or = 60% of control). 4. Due to the reduced detectability of small sparks against noise background, the observed data would overestimate reduction in spark frequency but underestimate amplitude reduction. After correction for this detection bias, we found that the spark frequency was independent of SR load, whereas the amplitude was proportional to load. 5. We conclude that, although spark amplitude depends on SR filling status, the frequency of spark generation is independent of SR calcium load, and therefore independent of the local calcium release rate. This implies that sparks are single-channel events, or collective events that are well above threshold for local regeneration. Additionally, our results suggest that intraluminal SR calcium, at normal or low loads, does not play a major role in the regulation of on-gating of the ryanodine receptor.
Similar articles
- Ca2+ diffusion and sarcoplasmic reticulum transport both contribute to [Ca2+]i decline during Ca2+ sparks in rat ventricular myocytes.
Gómez AM, Cheng H, Lederer WJ, Bers DM. Gómez AM, et al. J Physiol. 1996 Oct 15;496 ( Pt 2)(Pt 2):575-81. doi: 10.1113/jphysiol.1996.sp021708. J Physiol. 1996. PMID: 8910239 Free PMC article. - Dynamic regulation of sarcoplasmic reticulum Ca(2+) content and release by luminal Ca(2+)-sensitive leak in rat ventricular myocytes.
Lukyanenko V, Viatchenko-Karpinski S, Smirnov A, Wiesner TF, Györke S. Lukyanenko V, et al. Biophys J. 2001 Aug;81(2):785-98. doi: 10.1016/S0006-3495(01)75741-4. Biophys J. 2001. PMID: 11463625 Free PMC article. - Effects of [Ca2+]i, SR Ca2+ load, and rest on Ca2+ spark frequency in ventricular myocytes.
Satoh H, Blatter LA, Bers DM. Satoh H, et al. Am J Physiol. 1997 Feb;272(2 Pt 2):H657-68. doi: 10.1152/ajpheart.1997.272.2.H657. Am J Physiol. 1997. PMID: 9124422 - Elementary calcium release events from the sarcoplasmic reticulum in the heart.
Brochet DX, Yang D, Cheng H, Lederer WJ. Brochet DX, et al. Adv Exp Med Biol. 2012;740:499-509. doi: 10.1007/978-94-007-2888-2_21. Adv Exp Med Biol. 2012. PMID: 22453956 Free PMC article. Review. - Sarcoplasmic reticulum Ca release in intact ventricular myocytes.
Bers DM. Bers DM. Front Biosci. 2002 Jul 1;7:d1697-711. doi: 10.2741/A873. Epub 2002 Jul 1. Front Biosci. 2002. PMID: 12086924 Review.
Cited by
- High speed sCMOS-based oblique plane microscopy applied to the study of calcium dynamics in cardiac myocytes.
Sikkel MB, Kumar S, Maioli V, Rowlands C, Gordon F, Harding SE, Lyon AR, MacLeod KT, Dunsby C. Sikkel MB, et al. J Biophotonics. 2016 Mar;9(3):311-23. doi: 10.1002/jbio.201500193. Epub 2015 Oct 21. J Biophotonics. 2016. PMID: 26488431 Free PMC article. - Ryanodine receptor gating controls generation of diastolic calcium waves in cardiac myocytes.
Petrovič P, Valent I, Cocherová E, Pavelková J, Zahradníková A. Petrovič P, et al. J Gen Physiol. 2015 Jun;145(6):489-511. doi: 10.1085/jgp.201411281. J Gen Physiol. 2015. PMID: 26009544 Free PMC article. - Effects of chronic administration of clenbuterol on contractile properties and calcium homeostasis in rat extensor digitorum longus muscle.
Sirvent P, Douillard A, Galbes O, Ramonatxo C, Py G, Candau R, Lacampagne A. Sirvent P, et al. PLoS One. 2014 Jun 27;9(6):e100281. doi: 10.1371/journal.pone.0100281. eCollection 2014. PLoS One. 2014. PMID: 24971566 Free PMC article. - Enhanced Ca²+ influx through cardiac L-type Ca²+ channels maintains the systolic Ca²+ transient in early cardiac atrophy induced by mechanical unloading.
Schwoerer AP, Neef S, Broichhausen I, Jacubeit J, Tiburcy M, Wagner M, Biermann D, Didié M, Vettel C, Maier LS, Zimmermann WH, Carrier L, Eschenhagen T, Volk T, El-Armouche A, Ehmke H. Schwoerer AP, et al. Pflugers Arch. 2013 Dec;465(12):1763-73. doi: 10.1007/s00424-013-1316-y. Epub 2013 Jul 11. Pflugers Arch. 2013. PMID: 23842739 Free PMC article. - Isoproterenol increases the fraction of spark-dependent RyR-mediated leak in ventricular myocytes.
Santiago DJ, Ríos E, Shannon TR. Santiago DJ, et al. Biophys J. 2013 Mar 5;104(5):976-85. doi: 10.1016/j.bpj.2013.01.026. Biophys J. 2013. PMID: 23473480 Free PMC article.
References
- Science. 1970 Jan 2;167(3914):58-9 - PubMed
- Annu Rev Biophys Biomol Struct. 1997;26:47-82 - PubMed
- J Gen Physiol. 1985 Feb;85(2):247-89 - PubMed
- Science. 1987 Jan 16;235(4786):325-8 - PubMed
- Cell Calcium. 1988 Dec;9(5-6):247-56 - PubMed
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Research Materials