Inhibition cAMP-phosphodiesterase in the rat heart by pentoxifylline--a new xanthine derivative.

Pentoxifylline, a new xanthine derivative with properties favorably affecting the rheological profile of blood, was administered to male rats weighing 200--300 g in doses of 5, 10, 15, and 20 mg/kg of body weight for five days. Up to 27% of the intracellular cAMP-phosphodiesterase (cAMP-PDE) of the myocardium was dose-dependently inhibited. A significant increase in the protein content of the heart (wet weight) was also recorded, but was unrelated to the dose of pentoxifylline and without evidence of cardiac hypertrophy.