Cardioprotective actions of pentoxifylline in an animal model of acute myocardial ischaemia

The action of pentoxifylline on some of the consequences of acute myocardial ischaemia was studied in cats in vivo. Occlusion of the left anterior descending coronary artery (LAD) for 5 h resulted in a significant elevation in the ST-segment of the ECG, a reduction in free platelet count in right atrial blood and a loss of creatine phosphokinase (CK) and cathepsin D activities in homogenates of the severely ischaemic myocardium as compared to non-ischaemic myocardium. Intravenous infusions of pentoxifylline (0.30 mg kg-1 min-1 for 1 h and 0.15 mg kg-1 min-1 for the remainder of the 5 h observation period, starting 0.5 h after LAD occlusion) significantly reduced the loss of enzymes from the ischaemic myocardium, prevented any further increase in the ST-segment and restored the platelet count to its control level. There were no significant changes in plasma immunoreactive 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha) and thromboxane B2 (TXB2), although a tendency for a reduction in TXB2 levels was observed. Pentoxifylline seems to affect, beneficially, the myocardium in this animal model of acute myocardial ischaemia. The reason for this cardioprotective action remains to be elucidated. It is, however, noteworthy that the overall profile of action of pentoxifylline resembles that of PGI2 administration in this model.