title: Metabolic regulation of Ca2+ release in permeabilized mammalian skeletal muscle fibres.
abstract: In the present study, the link between cellular metabolism and Ca2+ signalling was investigated in permeabilized mammalian skeletal muscle. Spontaneous events of Ca2+ release from the sarcoplasmic reticulum were detected with fluo-3 and confocal scanning microscopy. Mitochondrial functions were monitored by measuring local changes in mitochondrial membrane potential (with the potential-sensitive dye tetramethylrhodamine ethyl ester) and in mitochondrial [Ca2+] (with the Ca2+ indicator mag-rhod-2). Digital fluorescence imaging microscopy was used to quantify changes in the mitochondrial autofluorescence of NAD(P)H. When fibres were immersed in a solution without mitochondrial substrates, Ca2+ release events were readily observed. The addition of L-glutamate or pyruvate reversibly decreased the frequency of Ca2+ release events and increased mitochondrial membrane potential and NAD(P)H production. Application of various mitochondrial inhibitors led to the loss of mitochondrial [Ca2+] and promoted spontaneous Ca2+ release from the sarcoplasmic reticulum. In many cases, the increase in the frequency of Ca2+ release events was not accompanied by a rise in global [Ca2+]i. Our results suggest that mitochondria exert a negative control over Ca2+ signalling in skeletal muscle by buffering Ca2+ near Ca2+ release channels.
authors.affiliation: Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Isaeva
authors.forename: Natalia
authors.initials: N
authors.lastname: Shirokova
mesh_terms: D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D004338:Drug Combinations; D005260:Female; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009840:Oligomycins / Q000494:pharmacology; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley; D017975:Ruthenium Compounds / Q000494:pharmacology; D015398:Signal Transduction
chemical_list: D004338:Drug Combinations; D009840:Oligomycins; C112020:Ru 360; D017975:Ruthenium Compounds; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000968:Antimycin A; D002118:Calcium