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| HIDALGO,CECILIA; ARACENA,PAULA; SANCHEZ,GINA; DONOSO,PAULINA. |
| 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 µM [Ca2+], whereas in native cardiac vesicles, maximal stimulation of release required only 1 µM [Ca2+]. In 10 µM [Ca2+], free [Mg2+] < 0.1 mM produced marked inhibition of release from skeletal vesicles but free [Mg2+]... |
| Tipo: Journal article |
Palavras-chave: Redox state; Ryanodine receptors; Sarcoplasmic reticulum; Calcium release kinetics; Mg2+ inhibition; S-nitrosoglutathione. |
| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602002000200009 |
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| HIDALGO,CECILIA; BULL,RICARDO; MARENGO,JUAN J; PÉREZ,CLAUDIO F; DONOSO,PAULINA. |
| The effects of redox reagents on the activity of the intracellular calcium release channels (ryanodine receptors) of skeletal and cardiac muscle, or brain cortex neurons, was examined. In lipid bilayer experiments, oxidizing agents (2,2'-dithiodipyridine or thimerosal) modified the calcium dependence of all single channels studied. After controlled oxidation channels became active at sub µM calcium concentrations and were not inhibited by increasing the calcium concentration to 0.5 mM. Subsequent reduction reversed these effects. Channels purified from amphibian skeletal muscle exhibited the same behavior, indicating that the SH groups responsible for modifying the calcium dependence belong to the channel protein. Parallel experiments that... |
| Tipo: Journal article |
Palavras-chave: Calcium dependence; Neurons; Redox state; Ryanodine receptors; Sarcoplasmic reticulum; Skeletal and cardiac muscle. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602000000200011 |
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