Ethanol increases calcium permeability of heavy sarcoplasmic reticulum of skeletal muscle.
The effects of ethanol on both Ca2+ pump activity and Ca2+-induced Ca2+ release in sarcoplasmic reticulum (SR) of rabbit skeletal muscle were studied. In concentrations of 0.1-1.0%, ethanol conspicuously enhanced Ca2+ release from the heavy fraction of SR, whereas a much smaller effect was noted in the light fraction. When Ca2+-induced Ca2+ release was inhibited by 10 mM Mg2+, the Ca2+ pump activities of both the heavy and light SR were the same; the activities were not significantly influenced by 1% ethanol. Ethanol itself did not release Ca2+ from the heavy SR. However, it appeared to render the heavy SR more permeable to Ca2+, thereby decreasing the amount of storable Ca2+. This action of ethanol may be related to the mechanism of its negative inotropic effect.
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D000431:Ethanol / Q000494:pharmacology*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D010539:Permeability; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology
D000431:Ethanol; D013395:Sucrose; D008274:Magnesium; D002118:Calcium