Effect of α-difluoromethylornithine on cardiac polyamine content and hypertrophy

Cardiac hypertrophy produced by treatment with thyroxine for 7 days was accompanied by a significant increase in polyamine content. Putrescine was elevated by 4- to 5-fold, spermidine by 1.6-fold and spermine 1.3-fold. Administration of α-difluoromethylornithine, a potent irreversible inhibitor of ornithine decarboxylase, prevented these increases provided that a high concentration of the drug was maintained by intraperitoneal injection of 200 mg/kg body wt every 12 h and supplementation of the drinking water with 3 g of the drug 100 ml. Such treatment with α-difluoromethylornithine prevented the rise in spermidine and spermine and reduced putrescine content to undetectable levels but did not prevent the increase in heart weight showing that the enhancement of polyamine concentration is not essential for thyroxine-induced cardiac hypertrophy.