Hydrogen peroxide stimulates the Ca2+ release channel from skeletal muscle sarcoplasmic reticulum.
Hydrogen peroxide (H2O2) at millimolar concentrations induces Ca2+ release from actively loaded sarcoplasmic reticulum vesicles and induces biphasic [3H]ryanodine binding behavior. High affinity [3H]ryanodine binding is enhanced at concentrations from 100 microM to 10 mM (3-4 fold). At H2O2 concentrations greater than 10 mM, equilibrium binding is inhibited. H2O2 decreased the kd for [3H]ryanodine binding by increasing its association rate, while having no effect on the rate of dissociation of [3H]ryanodine from its receptor. H2O2 (1 mM) also reduced the EC50 for Ca2+ activation from 632 nM to 335 nM. These effects were completely abolished in the presence of catalase, ruthenium red, and/or Mg2+ (Mm). H2O2-stimulated [3H]ryanodine binding is not further enhanced by either doxorubicin or caffeine. The direct interaction between H2O2 and the Ca2+ release mechanism was further demonstrated in single-channel reconstitution experiments. Peroxide, at submillimolar concentrations, activated the Ca2+ release channel following fusion of a sarcoplasmic reticulum vesicle to a bilayer lipid membrane. At millimolar concentrations of peroxide, Ca2+ channel activity was inhibited. Peroxide stimulation of Ca2+ channel activity was reversed by the thiol reducing agent dithiothreitol. Paralleling peroxide induced activation of ryanodine binding, Ca2+ transport, and single Ca2+ channel activity, it was observed that the ryanodine receptor formed large disulfide-linked protein complexes that dissociated upon addition of dithiothreitol.
Favero
T G
TG
Department of Biology, University of Portland, Oregon 97203, USA.
Zable
A C
AC
Abramson
J J
JJ
D000251:Adenosine Triphosphatases / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002110:Caffeine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects*; D002374:Catalase / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011817:Rabbits; D012430:Ruthenium Red / Q000494:pharmacology; D012433:Ryanodine / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000187:drug effects*; D013347:Subcellular Fractions / Q000378:metabolism
D015220:Calcium Channels; D007476:Ionophores; D012430:Ruthenium Red; D012433:Ryanodine; D000001:Calcimycin; D002110:Caffeine; D004317:Doxorubicin; D006861:Hydrogen Peroxide; D002374:Catalase; D000251:Adenosine Triphosphatases; D002118:Calcium; D004229:Dithiothreitol