STUDY OF THE HEMORRHAGING PROCESS INDUCED BY THE VENOM OF Bothrops erythromelas

THESIS: R.C. Valença submitted this dissertation to obtain the degree of Master of Biophysics, publicly examined at the Biophysics and Radiobiology Department of the Federal University of Pernambuco, Recife, Brazil, in August 1997.

Advisor: Dra. Míriam Camargo Guarnieri

ABSTRACT. Hemorrhage is one of most significant consequences of Viperid envenomation. This study characterized the hemorrhagic effect of Bothrops erythromelas venom and determined its importance in envenomation by this specie. The hemorrhagic activity was evaluated to determine the minimum hemorrhagic dose of Bothrops erythromelas venom by subcutaneous and intradermal injections. These values were 8.3 and 21 mg/mouse, respectively. Samples of crude venom were incubated for 15 min at different temperatures. These were used to demonstrate that hemorrhagic activity was stable between 30°C and 50°C, but no longer apparent above 60°C. EDTA, p-APMSF, 1,10-phenanthroline and dithiothreitol completely inhibited hemorrhagic activity, while TPCK and benzamidine were ineffective, suggesting that B. erythromelas hemorrhagins are metalloproteases and dissulfide bonds are also apparently necessary for this biological activity. Gel filtration chromatography on Sephacryl S-200 HR showed that B. erythromelas contains proteins with weights between 170 KD and 2.7 KD. However, hemorrhagic activity was restricted to fractions with weights of 55 KD, 100 KD and 170 KD. Eight male dogs were i.v. infused with 0.5 mg of venom/Kg of venom for 30 minutes to determine which organs were most severely affected by the venom and to analyze its macro and microscopic effects. Six control animals were infused with 0.85% NaCl. The four surviving envenomed animals were examined. These animals showed gingival hemorrhage (50%), cutaneous hemorrhage petechiae (50%), haematuria (50%) and bleeding at surgical incision sites (100%). The macroscopic analysis of the lungs, kidneys and liver showed hemorrhagic areas and congestion (100%), whereas in the mesentery, stomach, and small intestine hemorrhagic areas were seen in only half the dogs. The histological examination of the lungs revealed swelling of the alveolar wall, considerable amount of blood in the lumens of bronchi and bronchioles, decreased bronchiolar diameter resulting from smooth muscle contraction. Glomerular intertubular vascular congestion and proximal intratubular hematic extravasation were seen in the kidneys. The liver showed swelling of the centrolobular veins, disorganized areas of hepatic parenchyma, and intense portal and sinus congestion. Fifty percent of the dogs showed subepicardial and endocardial hemorrhage, hematic extravasation in mesenteric fatty cells and vascular congestion in intestinal villae. Erythrocytes were found to be intact in all the affected organs, indicating acute Hemorrhage, whereas histological alterations were not found in the stomach and spleen. These results indicate that Bothrops erythromelas envenomation induces acute systemic hemorrhage, affecting mainly the lungs, kidneys, and liver.

CORRESPONDENCE TO:

R.C. VALENÇA - Departamento de Zoologia, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária, CEP 50670-901, Recife, Pernambuco, Brazil.

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Publication Dates

• Publication in this collection
  16 Apr 1999
• Date of issue
  1999