Inability of propranolol to prevent alcohol-induced reductions in cardiac protein synthesis in vivo

Abstract

Rats were acutely injected with alcohol (75 mmol/kg body weight) and at the end of 2.5 h changes in cardiac synthesis rates were assessed with a ‘flooding dose’ of l-[4- 3H]phenylalanine. The results showed that acute alcohol dosage reduced the fractional rates of cardiac protein synthesis ( k S, %/day). This effect was also seen when data were expressed relative to either RNA (i.e. k RNA, mg protein/day/mg RNA) or DNA (i.e. k DNA, mg protein/day/mg DNA). Both left and right ventricles responded similarly to ethanol. However, propranolol pre-treatment (at doses of 17 and 170 μmol/kg body weight; i.p.) did not prevent these effect of ethanol in either the left or right ventricle. Indeed, there was evidence that propranolol per se perturbed cardiac protein synthesis in vivo in control (i.e. without ethanol) rats particularly in the right ventricle. In conclusion, the results suggest that alcohol is cardiotoxic to the myocardium, which may cause its effects on protein synthesis independently of β-receptors and/or xanthine oxidase inhibition.