PLATELET-ACTIVATING-FACTOR (PAF) DOES NOT AFFECT DIASTOLIC FUNCTION IN ISOLATED RAT HEARTS

Platelet-activating factor might be responsible for the alterations of diastolic function observed in different disease states and these pot ential effects have not been studied. The effect of incremental concen trations of platelet-activating factor (to a maximum of 200 nM) was th erefore examined in isolated perfused rat heart. Platelet-activating f actor decreased coronary flow rate and contractility in a dose-depende nt manner. Although high-dose platelet-activating factor decreased pea k -dP/dt compared to baseline, this was not significant when compared to vehicle-administered control. There were no changes in the time con stant of left ventricular relaxation and the chamber stiffness constan t. These results do not support a major direct role of platelet-activa ting factor in diastolic dysfunction.