Effect of prolonged alcohol administration on calcium transport in heart muscle of the dog.

The effect of prolonged administration of alcohol on calcium binding and uptake by sarcoplasmic reticulum and mitochondria and on respiratory function of mitochondria was investigated in heart muscle of dogs. Dogs were paired and maintained with and without alcohol for 6 months; alcohol was administered by adding it to drinking water and food with vitamin supplements. Measurements were made after alcohol had been temporarily withheld for 2 days. Prolonged alcohol ingestion resulted in a decline in calcium binding and uptake by sarcoplasmic reticulum and mitochondria, suggesting a diminished affinity of the reticular and mitochondrial membranes for calcium ions. The endogenous calcium content of mitochondria and sarcoplasmic reticulum decreased. Prolonged alcohol administration failed to alter cardiac contractility, although contraction and relaxation tended to diminish following the administration of angiotensin. The results illustrate that one link in the regulation of the state of contraction or relaxation involving myofibrillar calcium transport is weakened in dogs maintained on alcohol for prolonged periods of time.