Effect of platelet-activating factor and its receptor antagonist, SRI 63-675, on gastric bleeding in rats

Gastric bleeding from an induced mucosal wound was monitored for 2 h in a rat model in which the normal haemostasis was disturbed mechanically by perfusing the lesion with saline. The bleeding pattern was characterized by continuous and/or rebleeding episodes. Intravenous infusion of platelet-activating factor (PAF) in a dose of 25 ng/kg/min reduced the blood loss by 92% without affecting the bleeding pattern or the macroscopic appearance of the mucosa significantly. Concomitant administration of the PAF receptor antagonist SRI 63-675 in a dose of 50 micrograms/kg/min completely reversed the effects of PAF. The bleeding was unchanged after PAF receptor antagonist alone, suggesting that endogenous PAF might not participate in the in vivo haemostasis after an acute gastric mucosal lesion.