Prevention by Phospholipase C of Pulmonary Insufficiency Syndrome Induced by Tissue Thromboplastin in Rats

Purified phospholipase C (PLC) is a potent inactivator of tissue thromboplastin in vitro (1.2). Rats injected with a lethal dose of purified human tissue thromboplastin (3) survived when given PLC i.v. before the thromboplastin injection (4.5). PLC i.v. also led to a striking reduction ¹²⁵I-fibrin and ⁵¹Cr-platelets in the lungs when given just before a sublethal infusion of thromboplastin (5). Rat adipose tissue was homogenized and centrifuged to give 3 fractions, of which one had a marked procoagulant, tissue thromboblastin-like activity. Infusion of this fraction led to an accumulation of ¹²⁵I-fibrin and ⁵¹Cr-platelets similar to that following infusion of tissue thromboplastin. LD⁵⁰ for purified PLC in rats have been determined (6). Doses smaller than 10% of LD₅₀ protected rats against otherwise lethal doses of the procoagulant from adipose tissue and reduced the accumulation of fibrin and platelets in the lungs to nearly control levels.PLC does not alter the primary bleeding time, platelet half-life or thrombin-induced platelet aggregation.1. Otnasss et al E.J.B. 1972, 2. Bjørklid et al TDH 1973, 3. Bjørklid et al BBRC 1973, 4. Giercksky et al S.J.H. 1976, 5. Giercksky & Bjørklid, S.J.H. 1976, 6. Otnæss et al S.J.C. lab. 1976.

 

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