%0 Journal Article
%T Redox regulation of calcium release in skeletal and cardiac muscle
%A HIDALGO
%A CECILIA
%A ARACENA
%A PAULA
%A SANCHEZ
%A GINA
%A DONOSO
%A PAULINA
%J Biological Research
%D 2002
%I Sociedad de Biolog¨ªa de Chile
%R 10.4067/S0716-97602002000200009
%X in skeletal and cardiac muscle cells, specific isoforms of the ryanodine receptor channels mediate ca2+ release from the sarcoplasmic reticulum. these channels are highly susceptible to redox modifications, which regulate channel activity. in this work, we studied the effects of ca2+ (endogenous agonist) and mg2+ (endogenous inhibitor) on the kinetics of ca2+ release from sarcoplasmic reticulum vesicles isolated from skeletal or cardiac mammalian muscle. native skeletal vesicles exhibited maximal stimulation of release kinetics by 10-20 ¦Ìm [ca2+], whereas in native cardiac vesicles, maximal stimulation of release required only 1 ¦Ìm [ca2+]. in 10 ¦Ìm [ca2+], free [mg2+] < 0.1 mm produced marked inhibition of release from skeletal vesicles but free [mg2+] - 0.8 mm did not affect release from cardiac vesicles. incubation of skeletal or cardiac vesicles with the oxidant thimerosal increased their susceptibility to stimulation by ca2+ and decreased the inhibitory effect of mg2+ in skeletal vesicles. sulfhydryl-reducing agents fully reversed the effects of thimerosal. the endogenous redox species, glutathione disulfide and s-nitrosoglutathione, also stimulated release from skeletal sarcoplasmic reticulum vesicles. in 10 ¦Ìm [ca2+], 35s-nitrosoglutathione labeled a protein fraction enriched in release channels through s-glutathiolation. free [mg2+] 1 mm or decreasing free [ca2+] to the nm range prevented this reaction. possible physiological and pathological consequences of redox modification of release channels on ca2+ signaling in heart and muscle cells are discussed
%K redox state
%K ryanodine receptors
%K sarcoplasmic reticulum
%K calcium release kinetics
%K mg2+ inhibition
%K s-nitrosoglutathione.
%U http://www.scielo.cl/scielo.php?script=sci_abstract&pid=S0716-97602002000200009&lng=en&nrm=iso&tlng=en