Intravenous injections of tissue thromboplastin and phospholipase C in rabbits.

Previous experiments (Gollub et al. [10]. Giercksky et al.) have shown that phospholipase C (PLC) has a protective effect on rats and rabbits receiving thromboplastin infusions. As a step towards the possible use of PLC in humans, we have investigated further the use of PLC in rabbits. Infusions of human or rabbit thromboplastin caused a rapid fall in factors V and VIII. LD50 for our standard human thromboplastin preparation was estimated to be 1.5--1.8 ml/kg. Highly purified PLC was given as an intravenous bolus immediately before thromboplastin. No improvement of survival and only a slight difference in factors V and VIII were observed, in contrast to earlier observations in the rat. This may in part be due to differences in the susceptibility to PLC of the thromboplastins used. PLC was also more toxic in rabbits than in rats.