Cardiovascular responses to Bothrops alternatus (Urutu) snake venom in anesthetized dogs.

The cardiovascular responses to Bothrops alternatus snake venom in anesthetized dogs were investigated. Venom (0.3 mg/kg, i.v.) markedly decreased arterial blood pressure, coronary perfusion pressure, and cardiac output (CO) after 5 min, with progressive recovery of the first two parameters to pre-venom levels after 3 h; CO showed little recovery. There was an abrupt, sustained decrease in left and right ventricular systolic work and stroke volume but no significant changes in heart rate, electrocardiogram, and pulmonary hemodynamics; systemic vascular resistance increased from 1 h onwards. A venom dose of 1 mg/kg produced more pronounced cardiovascular alterations, with a progressive decrease to death. There were no significant changes in blood gas (pO(2), pCO(2), HCO(3), SBC, and SBE) and metabolic (pH, lactate, glucose, creatine kinase activity, Na(+), and K(+)) parameters, although there was a transitory increase in plasma lactate dehydrogenase 2 min after the lower venom dose. There were no cardiac histological alterations, but microaneurysms and epithelial desquamation were seen in renal tubules. Circulating venom concentrations (determined by ELISA) decreased rapidly after administration, but venom was still detectable after 4 h. These results show that in dogs, B. alternatus venom produces marked hypotension and a direct cardiac action, with few metabolic alterations.

Renal kinetics of Bothrops alternatus (Urutu) snake venom in rats.

The renal kinetics of Bothrops alternatus venom (0.8 mg/kg, i.v.) was studied in conscious male Wistar rats. Blood, urine and renal tissue samples were collected at various intervals after envenoming. Venom was quantified by ELISA in serum, renal tissue and urine. Urine volume was measured and the urine assayed for urobilinogen, glucose, bilirubin, ketones, urine specific gravity, occult blood, pH, protein, nitrite and leucocytes. Circulating venom showed biexponential kinetics, with no venom being detected after 7 days post-venom. Venom was detected in renal tissue 30 min post-venom but decreased progressively thereafter, in parallel with serum venom concentrations. Immunohistochemistry detected venom in glomeruli, proximal and distal tubules, and vascular and perivascular tissue. Venom was detected in urine 3, 6 and 24 h post-venom. Oliguria occurred 3 h to 7 days post-venom, urine acidification occurred 3-6 h post-venom, urine specific gravity increased in the first 3 h and proteinuria was also greatest in this period. Creatinine clearance decreased progressively until 24-48 h post-venom, then returned to normal. Glucose, ketones, leucocytes and occult blood were detected mainly during the first 6 h post-venom. These results indicate reversible alterations in renal function, with renal elimination of the venom.

Biological activities of a lectin from Bothrops jararacussu snake venom.

Snake venoms contain saccharide-binding lectins. In this work, we examined the biological activities of a lectin (BjcuL) purified from Bothrops jararacussu snake venom by chromatography on non-derivatized Sepharose 4B and Sephacryl S-200 HR. The protein, a homodimer with subunits of 14.5 kDa, gave a single immunoprecipitin line in immunoelectrophoresis and cross-reacted in ELISA with antivenoms raised against Bothrops spp. (lanceheads), Micrurus spp. (coral snakes), Crotalus durissus terrificus (South American rattlesnake), and arthropod (Loxosceles gaucho, Phoneutria nigriventer and Tityus serrulatus) venoms. BjcuL agglutinated human formaldehyde-fixed erythrocytes at > or = 100 ng/ml and was inhibited by lactose and EDTA (> or = 2 mM) and high concentrations (> 100 mM) of glucose and sucrose, but not by N-acetylglucosamine. BjcuL had no direct hemolytic activity and was devoid of esterase, PLA2 and proteolytic activities. The lectin (up to 200 microg/ml) did not aggregate human platelet-rich plasma (PRP) or washed platelets (WP), nor did it alter the aggregation induced by ADP in PRP or by thrombin in WP. When injected into mouse hind paws, BjcuL (10-100 microg/paw) caused edema and increased vascular permeability, with a maximum effect after 1h that persisted for up to 6 h (edema) or gradually decreased after the peak interval (vascular permeability). No hemorrhage was observed in BjcuL-injected paws. In anesthetized rats, B. jararacussu venom (200 microg/kg, i.v.) produced sustained hypotension (maximum decrease of approximately 60%) whereas a similar dose of BjcuL decreased the blood pressure by approximately 15%, with a rapid return to the resting level.