Effect of catecholamines on ornithine decarboxylase activity monitored in the perfused rat heart

The activity of ornithine decarboxylase was monitored in situ by perfusing rat heart with (1-14COOH)-ornithine. Infusion of isoproterenol or noradrenaline caused after 15-20 min an activation of the ornithine decarboxylation 5 fold above control hearts; less evident was the effect of adrenaline. Isoproterenol induced ornithine decarboxylation was prevented by difluoromethyl-ornithine. Also propranolol produced a significative reduction of the flux of 14CO2 collected from the perfusate. The measurement of the ornithine decarboxylase activity in heart homogenates by confirming the above results, indicated that the in situ monitor of ornithine decarboxylation can represent an accurate method which reveals rapid activation of the enzyme.