Key result
Chronic alcohol ingestion in rats increases sarcoplasmic reticulum Ca2+ permeability but blunts acute ethanol effects.
Why the study?
The effect of chronic alcohol ingestion and acute ethanol exposure on the calcium permeability of sarcoplasmic reticulum in skeletal muscle was investigated.
Chronic alcohol ingestion increases baseline calcium permeability in rat skeletal muscle sarcoplasmic reticulum but blunts the further increase caused by acute ethanol exposure.
Hypothesis-generating for alcohol myopathy mechanisms; leaves open translation to human cardiac or skeletal muscle disease.
Heavy sarcoplasmic reticulum (SR) was prepared from skeletal muscle of control and chronic alcoholic rats, and the effect of in vitro addition of ethanol on the passive Ca2+ permeability was studied. The SR was loaded with Ca2+ in the absence of ATP. Then efflux was initiated by adding an EGTA solution to decrease the extravesicular Ca2+ concentration. The decrease of Ca2+ content of the SR was measured by an optical method using an encapsulated metallochromic indicator (calcein). The Ca2+ permeability of alcoholic rat SR was higher than that of control rats, especially at low external Ca2+ concentrations (below 1 microM). An in vitro (acute) exposure of SR to ethanol increased the Ca2+ permeability of the SR. However, the degree of increase in alcoholic rat SR was smaller than that in control rat SR.
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S. Tsuyoshi Ohnishi (1985) studied Chronic alcohol ingestion. Chronic alcohol ingestion and in vitro ethanol exposure vs. Control rats was evaluated on Passive Ca2+ permeability of sarcoplasmic reticulum. Chronic alcohol ingestion in rats increased the Ca2+ permeability of skeletal muscle sarcoplasmic reticulum compared to controls, while blunting the acute permeability-increasing effect of in vitro ethanol.
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