[Regulation of calcium liberation in sarcoplasmic reticulum and heart muscle cells]
العنوان: | [Regulation of calcium liberation in sarcoplasmic reticulum and heart muscle cells] |
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المؤلفون: | G, Callewaert, K R, Sipido |
المصدر: | Verhandelingen - Koninklijke Academie voor Geneeskunde van Belgie. 59(5) |
سنة النشر: | 1997 |
مصطلحات موضوعية: | Sarcoplasmic Reticulum, Chloride Channels, Myocardium, Action Potentials, Animals, Calcium, Heart, Calcium Channels, Ion Pumps, Rabbits, Myocardial Contraction |
الوصف: | The force of contraction of the heart muscle is largely determined by the amount of cytosolic Ca2+ ([Ca2+]) and the Ca2+ sensitivity of the myofilaments. Using patch-clamp techniques and fluorescent Ca2+ indicators (microfluorimetry) allowing the measurement of the cytosolic Ca2+ concentration under well-defined experimental conditions, we have analyzed the mechanisms underlying the [Ca2+]i transient in single cardiac myocytes. We conclude that in mammalian cardiac myocytes Ca2+ release from the sarcoplasmic reticulum (SR) is the main source of Ca2+ for activation of the myofilaments. Our results further show that the Ca2+ release channel of the SR is directly gated by Ca2+ influx through L-type Ca2+ channels that open during the action potential. Ca2+ influx via other pathways including the Na(+)-Ca2+ exchanger and T-type Ca2+ channels does not play a significant role in triggering Ca2+ release from the SR. Our results also clearly indicate that any change in the amplitude or time course of the [Ca2+]i transient leads to secondary changes in the duration of the action potential through specific actions on Ca2+ sensitive membrane currents. In particular, an increase in Ca2+ release will enhance Ca2+ efflux via the Na(+)-Ca2+ exchanger resulting in a depolarizing current and prolongation of the action potential. This prolongation of the action potential is to some extent compensated by pronounced inactivation of L-type Ca2+ channels and activation of a transient outward Cl- current. |
اللغة: | Dutch; Flemish |
تدمد: | 0302-6469 |
الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=pmid________::15dcf0f266de68c50cf2a98b5e82a75bTest https://pubmed.ncbi.nlm.nih.gov/9490926Test |
رقم الانضمام: | edsair.pmid..........15dcf0f266de68c50cf2a98b5e82a75b |
قاعدة البيانات: | OpenAIRE |