The effect of PAF (platelet-activating factor) on experimental cardiac arrhythmias and its inhibition by substances influencing arachidonic acid metabolites.

Platelet-activating factor (PAF), 10(-11) mol decreased the threshold of ouabain induced arrhythmia in guinea-pigs. The thresholds inducing premature ventricular beats and ventricular flutter were statistically significantly decreased by 27.4% and 15.6%, respectively. BM 13.177 (30 mg/kg), a thromboxane receptor antagonizing substance, and esculetin (1.2 mg/kg), a lipoxygenase inhibitor, abolished this arrhythmogenic effect of PAF. Acetylsalicylic acid (10 mg/kg) showed only a tendency to inhibit the PAF effect. These results suggest that PAF could play a role in cardiac arrhythmias under special conditions and it supports the hypothesis that PAF action is mediated by the release of leukotrienes and thromboxane.