Modulation by caffeine of calcium-release microdomains in frog skeletal muscle fibers
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JULIO L VERGARA [1] ; MARINO DIFRANCO [1]
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[1] University of California at Los Angeles (UCLA) David Geffen School of Medicine Department of Physiology
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- Localización: Biological Research, ISSN-e 0717-6287, ISSN 0716-9760, Vol. 39, Nº. 3, 2006, págs. 567-581
- Idioma: inglés
- Enlaces
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Resumen
The effects of caffeine on the process of excitation-contraction coupling in amphibian skeletal muscle fibers were investigated using the confocal spot detection technique. This method permits to carefully discriminate between caffeine effects on the primary sources of Ca2+ release at the Z-lines where the triads are located and secondary actions on other potential Ca Release sources. Our results demonstrate that 0.5 mM caffeine potentiates and prolongs localized action-potential evoked Ca2+ transients recorded at the level of the Z-lines, but that 1mM only prolongs them. The effects at both doses are reversible. At the level of the M-line, localized Ca2+ transients displayed more variability in the presence of 1 mM caffeine than in control conditions. At this dose of caffeine, extra-junctional sources of Ca2+ release also were observed occasionally.
