POLYAMINE-MEDIATED HEART HYPERTROPHY INDUCED BY CLENBUTEROL IN THE MOUSE

The use of beta-agonists as growth-promoting agents in cattle could le ad to toxic side-effects in man. One such effect is the accumulation o f polyamines which seem to be implicated in muscle and heart hypertrop hy. We have studied the induction of cardiac hypertrophy after treatme nt with clenbuterol and the role of polyamines in this effect. Treatme nt of mice with repeated doses of clenbuterol, a specific beta-adrener gic agonist, resulted in a marked increase in heart muscle weight wher eas total body weight did not change significantly. Clenbuterol-linked cardiac hypertrophy could be prevented by co-administration of either the non-specific beta-adrenergic antagonist, propranolol, or the irre versible inhibitor of ornithine decarboxylase, alpha-difluoromethylorn ithine. The clenbuterol-induced cardiac hypertrophy was associated wit h a corresponding increase in the level of the polyamines putrescine, spermidine and spermine. These observations are indicative of the role of polyamines in cardiac hypertrophy induced by clenbuterol.