Hypotensive and hemostatic properties of rattlesnake (Crotalus viridis helleri) venom and venom fractions in dogs.

Hypotensive and hemostatic properties of Southern Pacific rattlesnake (Crotalus viridis helleri) venom (100 micrograms/kg; i.v. bolus) or venom fractions (40 micrograms/kg) were studied in mongrel dogs (n = 27, 15-27 kg). Venom was separated by gel filtration (Sephadex G-100) into three lethal fractions (FR I, II and III). Nonreduced crude venom contained 11 main protein bands on sodium dodecyl sulfate-10% polyacrylamide gel electrophoresis with a molecular weight range of 104 to 13 kD. FR I contained nine of these prominent bands (104-27 kD) and FR II contained five bands (34-13 kD). A 19-13 kD band comprised 92% of FR III. Crude venom rapidly produced hypotension, thrombocytopenia, hemolysis, the generation of fibrin monomers and a decrease in Factor VIIIC activity. Fibrin/fibrinogen degradation products appeared at +15 min and fibrinogen concentration was significantly depressed at +120 min. There was no significant change in prothrombin time or concentration of Factors VII, X and XII activity. However, the partial thromboplastin time was increased (P less than .05) by +30 min. Our data show that a high molecular weight thrombin-like venom component in FR I (greater than 27 kD) directly digests fibrinogen without activation of extrinsic and intrinsic coagulation factors. In addition, this fraction leads to the activation of the fibrinolytic system. It appears to be likely that the thrombocytopenia is primarily the result of ca. 27 kD platelet aggregating protein found in similar amounts in FR I and II. Venom components in FR II (ca. 34 and 29 kD,) were associated with hypotension and hemolysis.(ABSTRACT TRUNCATED AT 250 WORDS)