tokens: v .) to rats elicited a marked decrease of mean arterial blood pressure (MBP) and heart rate (HR) leading to death ( in 67 % or 90 % of animals respectively ). Intravenous injection of the specific platelet - activating factor ( PAF ) antagonist BN 52021 ( 10 mg / kg ), 30 min before bupivacaine administration ( 2 mg / kg i .