TY - JOUR
T1 - Hypochlorous acid modifies calcium release channel function from skeletal muscle sarcoplasmic reticulum
AU - Favero, Terence G.
AU - Webb, Jason
AU - Papiez, Maria
AU - Fisher, Erin
AU - Trippichio, Robert J.
AU - Broide, Michael
AU - Abramson, Jonathan J.
PY - 2003/4/1
Y1 - 2003/4/1
N2 - We have previously demonstrated that H2O2 at millimolar concentrations induces Ca2+ release from actively loaded sarcoplasmic reticulum (SR) vesicles and induces biphasic [3H]ryanodine binding behavior. Considering that hypochlorous acid (HOCl) is a related free radical and has been demonstrated to be a more effective oxidant of proteins, we evaluated the effects of HOCl on sarcoplasmic reticulum Ca2+-channel release mechanism. In a concentration-dependent manner, HOCl activates the SR Ca2+ release channel and induces rapid release of Ca from actively loaded vesicles. HOCl-induced Ca2+ release is inhibited in the presence of millimolar concentrations of DMSO. High-affinity [3H]ryanodine binding is also enhanced at concentrations from 10 to 100 μM. At HOCl concentrations of >100 μM, equilibrium binding is inhibited. HOCl stimulation of binding is inhibited by the addition of dithiothreitol. The direct interaction between HOCl and the Ca2+ release mechanism was further demonstrated in single-channel reconstitution experiments. HOCl, at 20 μM, activated the Ca2+ release channel after fusion of a SR vesicle to a bilayer lipid membrane. At 40 μM, Ca2+-channel activity was inhibited. Pretreatment of SR vesicles with HOCl inhibited the fluorescence development of a fluorogenic probe specific to thiol groups critical to channel function. These results suggest that HOCl at micromolar concentrations can modify SR Ca2+ handling.
AB - We have previously demonstrated that H2O2 at millimolar concentrations induces Ca2+ release from actively loaded sarcoplasmic reticulum (SR) vesicles and induces biphasic [3H]ryanodine binding behavior. Considering that hypochlorous acid (HOCl) is a related free radical and has been demonstrated to be a more effective oxidant of proteins, we evaluated the effects of HOCl on sarcoplasmic reticulum Ca2+-channel release mechanism. In a concentration-dependent manner, HOCl activates the SR Ca2+ release channel and induces rapid release of Ca from actively loaded vesicles. HOCl-induced Ca2+ release is inhibited in the presence of millimolar concentrations of DMSO. High-affinity [3H]ryanodine binding is also enhanced at concentrations from 10 to 100 μM. At HOCl concentrations of >100 μM, equilibrium binding is inhibited. HOCl stimulation of binding is inhibited by the addition of dithiothreitol. The direct interaction between HOCl and the Ca2+ release mechanism was further demonstrated in single-channel reconstitution experiments. HOCl, at 20 μM, activated the Ca2+ release channel after fusion of a SR vesicle to a bilayer lipid membrane. At 40 μM, Ca2+-channel activity was inhibited. Pretreatment of SR vesicles with HOCl inhibited the fluorescence development of a fluorogenic probe specific to thiol groups critical to channel function. These results suggest that HOCl at micromolar concentrations can modify SR Ca2+ handling.
KW - Reactive oxygen
KW - Redox modification
KW - Ryanodine binding
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U2 - 10.1152/japplphysiol.00645.2002
DO - 10.1152/japplphysiol.00645.2002
M3 - Article
C2 - 12626470
AN - SCOPUS:0037377683
SN - 8750-7587
VL - 94
SP - 1387
EP - 1394
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 4
ER -