Both T- and L-type Ca2+ channels can contribute to excitation-contraction coupling in cardiac Purkinje cells - PubMed (original) (raw)
Both T- and L-type Ca2+ channels can contribute to excitation-contraction coupling in cardiac Purkinje cells
Z Zhou et al. Biophys J. 1998 Apr.
Abstract
Although L-type Ca2+ channels have been shown to play a central role in cardiac excitation-contraction (E-C) coupling, little is known about the role of T-type Ca2+ channels in this process. We used the amphotericin B perforated patch method to study the possible role of T-type Ca2+ current in E-C coupling in isolated canine Purkinje myocytes where both Ca2+ currents are large. T-type Ca2+ current was separated from L-type Ca2+ current using protocols employing the different voltage dependencies of the channel types and their different sensitivities to pharmacological blockade. We showed that Ca2+ admitted through either T- or L-type Ca2+ channels is capable of initiating contraction and that the contractions depended on Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR). The contractions, however, had different properties. Those initiated by Ca2+ entry through T-type Ca2+ channels had a longer delay to the onset of shortening, slower rates of shortening and relaxation, lower peak shortening, and longer time to peak shortening. These differences were present even when L-type Ca2+ current amplitude, or charge entry, was less than that of T-type Ca2+ current, suggesting that Ca2+ entry through the T-type Ca2+ channel is a less effective signal transduction mechanism to the SR than is Ca2+ entry through the L-type Ca2+ channel. We conclude that under our experimental conditions in cardiac Purkinje cells Ca2+ entry through the T-type Ca2+ channel can activate cell contraction. However, Ca2+ entry through the L-type Ca2+ channel is a more effective signal transduction mechanism. Our findings support the concept that different structural relationships exist between these channel types and the SR Ca2+ release mechanism.
Similar articles
- The voltage-sensitive release mechanism of excitation contraction coupling in rabbit cardiac muscle is explained by calcium-induced calcium release.
Griffiths H, MacLeod KT. Griffiths H, et al. J Gen Physiol. 2003 May;121(5):353-73. doi: 10.1085/jgp.200208764. J Gen Physiol. 2003. PMID: 12719483 Free PMC article. - Voltage dependence of cardiac excitation-contraction coupling: unitary Ca2+ current amplitude and open channel probability.
Altamirano J, Bers DM. Altamirano J, et al. Circ Res. 2007 Sep 14;101(6):590-7. doi: 10.1161/CIRCRESAHA.107.152322. Epub 2007 Jul 19. Circ Res. 2007. PMID: 17641229 - Spatial non-uniformities in [Ca2+]i during excitation-contraction coupling in cardiac myocytes.
Cannell MB, Cheng H, Lederer WJ. Cannell MB, et al. Biophys J. 1994 Nov;67(5):1942-56. doi: 10.1016/S0006-3495(94)80677-0. Biophys J. 1994. PMID: 7858131 Free PMC article. - [Regulation of calcium liberation in sarcoplasmic reticulum and heart muscle cells].
Callewaert G, Sipido KR. Callewaert G, et al. Verh K Acad Geneeskd Belg. 1997;59(5):401-34. Verh K Acad Geneeskd Belg. 1997. PMID: 9490926 Review. Dutch. - The 1996 Merck Frosst Award. The voltage-sensitive release mechanism: a new trigger for cardiac contraction.
Howlett SE, Ferrier GR. Howlett SE, et al. Can J Physiol Pharmacol. 1997 Sep;75(9):1044-57. doi: 10.1139/cjpp-75-9-1044. Can J Physiol Pharmacol. 1997. PMID: 9365812 Review.
Cited by
- Acetylcholine Reduces L-Type Calcium Current without Major Changes in Repolarization of Canine and Human Purkinje and Ventricular Tissue.
Verkerk AO, Doszpod IJ, Mengarelli I, Magyar T, Polyák A, Pászti B, Efimov IR, Wilders R, Koncz I. Verkerk AO, et al. Biomedicines. 2022 Nov 21;10(11):2987. doi: 10.3390/biomedicines10112987. Biomedicines. 2022. PMID: 36428555 Free PMC article. - New Insights in Cardiac Calcium Handling and Excitation-Contraction Coupling.
Gambardella J, Trimarco B, Iaccarino G, Santulli G. Gambardella J, et al. Adv Exp Med Biol. 2018;1067:373-385. doi: 10.1007/5584_2017_106. Adv Exp Med Biol. 2018. PMID: 28956314 Free PMC article. Review. - Microdomain-specific localization of functional ion channels in cardiomyocytes: an emerging concept of local regulation and remodelling.
Balycheva M, Faggian G, Glukhov AV, Gorelik J. Balycheva M, et al. Biophys Rev. 2015 Mar;7(1):43-62. doi: 10.1007/s12551-014-0159-x. Epub 2015 Jan 15. Biophys Rev. 2015. PMID: 28509981 Free PMC article. - Regulation of cardiac excitability by protein kinase C isozymes.
Ferreira JC, Mochly-Rosen D, Boutjdir M. Ferreira JC, et al. Front Biosci (Schol Ed). 2012 Jan 1;4(2):532-46. doi: 10.2741/s283. Front Biosci (Schol Ed). 2012. PMID: 22202075 Free PMC article. Review. - High purity human-induced pluripotent stem cell-derived cardiomyocytes: electrophysiological properties of action potentials and ionic currents.
Ma J, Guo L, Fiene SJ, Anson BD, Thomson JA, Kamp TJ, Kolaja KL, Swanson BJ, January CT. Ma J, et al. Am J Physiol Heart Circ Physiol. 2011 Nov;301(5):H2006-17. doi: 10.1152/ajpheart.00694.2011. Epub 2011 Sep 2. Am J Physiol Heart Circ Physiol. 2011. PMID: 21890694 Free PMC article.
References
- Nature. 1981 Apr 9;290(5806):527-8 - PubMed
- Science. 1997 May 2;276(5313):800-6 - PubMed
- J Physiol. 1984 Jul;352:217-41 - PubMed
- Circ Res. 1984 Sep;55(3):336-48 - PubMed
- Proc Natl Acad Sci U S A. 1984 Oct;81(20):6388-92 - PubMed
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Research Materials
Miscellaneous