WEB 2086, a novel specific PAF antagonist, prevents PAF induced arrhythmogenicity

The hetrazepine derivative WEB 2086 (0.5-2 mg/kg, i.v.), a well known PAF receptor antagonist, was found to reduce the arrhythmogenic effect of PAF in a dose dependent manner on ouabain induced arrhythmias in guinea-pigs. There was no detectable substance-specific influence of WEB 2086 on the threshold doses of ouabain, since in a dose of 2 mg/kg given i.v. it was able to inhibit cardiac rhythm disturbances induced by PAF as well. Guinea-pigs actively sensitized with ovalbumin responded to antigenic challenge with an increased susceptibility to ouabain induced arrhythmias. This arrhythmogenic effect could also be inhibited by WEB 2086. In conclusion, WEB 2086 was found to exert marked protective effects against PAF related cardiac arrhythmias, indicating its potential usefulness for the treatment of cardiac anaphylaxis.