INHIBITORS OF FIBRINOLYSIS IN THE EUGLOBULIN FRACTION OF SNAKE PLASMA (Bothrops j araraca)

Abstract

Blood of most Reptilia has a naturally occurring circulating anticoagulant which inhibits thrombin activity. Besides, the intrinsic thromboplastin formation is deficient in snakes, and contact phase factors were not detected when measured on heterologous substrates. No records on fibrinolytic activity were found. The fibrinolytic activity of the euglobulin fraction of snake plasma (B, jararaca) in standard conditions is here reported. Nembutal anesthetized male and female animals were used for blood collection from the aorta artery and/or a vein after surgical exposure. Euglobulin fractions (EF) of plasma were obtained by dilution (1:10) and isoelectric precipitation (5.9). Activity was tested on human fibrin plates, immediately after preparation (EF1), after 24 hours at 4°C (EF2), and in both cases, in the presence of 2.1 m>: flufenamil-beta-alanine (Flu-beta-Ala)(EF3, EF4). Euglobulin clot lysis time (ECLT) was also determined. Fibrinolytic activity on the heterologous fibrin plate was obtained with EF1 of male plasma but the range of variation was high (23 to 100 mm2). Activity increased from EF1 to EF4 but never reached human EF values. They were much lower in female EF1 with about 70% negative results. On the other hand, ECLT of EF3 from both male and female plasma was markedly shortened when compared to the long and extremely variable results obtained with EF1. Also, snake EF1 prolonged the ECLT of human EF1. Results suggest that snake plasma contains high levels of inhibitors of fibrinolysis that are coprecipitated with the EF, and this is more intense with female plasma. The nature of such inhibitors has to be investigated.