Enzyme activity changes in rat heart after chronic alcohol ingestion.

The effect of a chronic intake of dietary alcohol upon myocardial enzymes was studied in rats. Alcohol, comprising more than 40% of the dietary calorie content, was administered to rats for 6 or 12 weeks. To assess the metabolic changes in the myocardium, the following enzymes were measured: lactate dehydrogenase (LDH), malate dehydrogenase (MDH), aldolase (ALD), isocitrate dehydrogenase (ICDH), creatine kinase (CK) and glutamate-pyruvate transaminase (GPT). The activity of CK was decreased (4.79 +/- 0.99 U X mg-1 protein) after 6 weeks on alcohol and was significantly different from that of the controls (5.98 +/- 1.44 U X mg-1 protein). After 12 weeks the CK activity of alcoholic rats had recovered to 5.99 +/- 1.08 U X mg protein-1 and approached the value found in the normal myocardium. A pronounced decrease was found in the activity of MDH: 8.26 +/- 0.69 U X mg protein-1 in the controls, and 6.78 +/- 1.07 U X mg protein-1 and 5.79 +/- 0.85 U X mg protein-1 in the alcoholic rats after 6 and 12 weeks, respectively. The LDH activity decreased to a lesser extent, but significantly: 2.45 +/- 0.18 U X mg protein-1 in the controls, and 2.11 +/- 0.07 U X mg protein-1 and 2.06 +/- 0.29 U X mg protein-1 after 6 and 12 weeks on test. Only slight, not significant, changes were observed for the other enzymes investigated (ICDH, ALD, GPT).(ABSTRACT TRUNCATED AT 250 WORDS)