Direct Toxic Effect Of Ethanol Research Articles

Cardiac metabolsim: its contributions to alcoholic heart disease and myocardial failure.

Changes in cardiac metabolism in myocardial failure and after alcohol ingestion are discussed. The main effect of alcohol ingestion is loss of cardiac contractility. Since heart muscle does not contain alcohol dehydrogenase, its toxicity is probably the result of a direct toxic effect of ethanol and acetaldehyde on the myocardial cell, possibly involving various membrane systems. Alcohol inhibits mitochondrial respiration and the activity of enzymes in the tricarboxylic acid cycle, and its interferes with both mitochondrial calcium uptake and binding. Ethanol profoundly affects myocardial lipid metabolism. Acetaldehyde diminishes myocardial protein synthesis and inhibits Ca++-activated myofibrillar ATPase. In myocardial failure, a series of possibilities may be responsible for the loss of contractility. Excitation-contraction coupling could be disturbed at the level of the sarcolemma, at the sarcoplasmic reticulum, at the mitochondria, and between calcium and the regulatory proteins. Deficiencies in Ca++ delivery systems of excitation-contraction coupling on the myosin ATPase activity could be responsible for the dimunition in cardiac contractility. Mitochondrial function may also be involved, since mitochondria from failing human hearts are defective with respect to respiratory control and calcium accumulation. Under certain conditions, the relationship of mitochondria to calcium sequestration is very important in influencing contractility. The involvement of contractile and regulatory proteins in myocardial failure cannot be excluded.

Alcohol-induced malabsorption of vitamin B12 in man.

INTOXICATION with alcohol is frequently associated with diarrhoea, and disturbances of intestinal function have been reported to be common in chronic alcoholics studied shortly after drinking-bouts1–5. Because the normal diet of alcoholics is characteristically poor, it is not clear whether the transient malabsorption frequently found can be attributed to a direct toxic effect of ethanol on the small intestine, or to a nutritional deficiency. We therefore studied the effects of the experimental ingestion of ethanol in man on vitamin B12 absorption under controlled metabolic ward conditions in the absence of nutritional deficiency.