Ethanol inhibition of spontaneous calcium release from isolated sarcoplasmic reticulum of alcoholic rats

Ethanol is a well-recognized cause of muscle damage in humans. In vitro, ethanol decreases muscle fiber twitch tension by a mechanism unrelated to the electrical events of the motor endplates or muscle surface membranes. One possible explanation for this effect is a primary ethanol effect on calcium release from the sarcoplasmic reticulum (SR). Ethanol has been shown to progressively decrease a form of calcium release from isolated SR vesicles seen in vitro in the presence of high phosphate concentrations ("spontaneous calcium release"). In this study, ethanol is shown to have similar inhibiting effects on spontaneous calcium release from sarcoplasmic reticulum isolated from alcoholic rats and from pair-fed controls. This suggests that membrane adaptation to chronic ethanol exposure, such as has been described for brain and liver membranes, does not produce tolerance to ethanol effects on spontaneous calcium release in sarcoplasmic reticulum.