Effect of Zn2+ ions on ryanodine binding to sarcoplasmic reticulum of striated muscles in the presence of pyrithione.
OBJECTIVE
To explore whether the differential effects of Zn2+ on ryanodine binding to the sarcoplasmic reticulum (SR) of skeletal and cardiac muscles resulted from different permeability of the SR to Zn2+.


METHODS
[3H]ryanodine binding assays were performed to examine the effect of Zn2+ on ryanodine binding to the SR in the presence of pyrithione sodium (PyNa), a specific Zn2+ ionophore.


RESULTS
As a control, PyNa up to 50 micromol/L did not induce any effect on ryanodine binding to the SR of cardiac muscle. But PyNa 1-100 micromol/L increased ryanodine binding in skeletal muscle with maximum binding (222.2+/-20.9 % of the control) and inhibited ryanodine binding to 50 % of the control at about 500 micromol/L. In the presence of PyNa 10 and 50 micromol/L the dose-dependence of the effect of Zn2+ in cardiac muscle was still monophasic and not changed by PyNa, while the biphasic effect of Zn2+ in skeletal muscle became monophasic.


CONCLUSIONS
Different permeability of the SR to Zn2+ may account for the differential effects of Zn2+ on ryanodine binding in skeletal and cardiac muscles. PyNa is not a strictly specific Zn2+ ionophore.
Xie
Hong
H
Unit of Cell Signal Transduction, Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Chen
Ke-ying
KY
Zhu
Pei-hong
PH
D000818:Animals; D004305:Dose-Response Relationship, Drug; D007476:Ionophores; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013871:Thiones; D015032:Zinc / Q000494:pharmacology*
D007476:Ionophores; D011725:Pyridines; D019837:Ryanodine Receptor Calcium Release Channel; D013871:Thiones; D012433:Ryanodine; C008704:pyrithione; D015032:Zinc