The involvement of plasma kinins in the cardiovascular effects of Leiurus quinquestriatus scorpion venom in anaesthetised rabbits.

The present study was undertaken to investigate the involvement of kinins in the cardiovascular- and respiratory effects of LQQ venom. Blood pressure, heart rate, electrocardiogram (ECG) and respiration were studied in anaesthetised rabbits, in the presence and absence of aprotinin and icatibant, a B2 bradykinin antagonist. Plasma bradykinin concentrations were also measured following venom injection. LQQ venom caused a triphasic effect on blood pressure comprising an immediate fall, a pronounced rise and a progressive decline until death. Bradycardia, myocardial damage, arrhythmias, respiratory distress and pulmonary oedema were also exhibited. Pretreatment with aprotinin attenuated the venom-induced hypotension, bradycardia, ECG and respiratory changes and prolonged survival. Pretreatment of atropinized animals with icatibant gave similar protection. In animals treated with LQQ venom, plasma bradykinin was significantly higher than controls, although there was considerable inter-animal variation in plasma kinin concentrations and the elevation was seen relatively late after venom administration. The data provides some support for the hypothesis that kinins are involved in the cardiovascular and lethal effects of LQQ venom in rabbits.