Estudos bioquimico e farmacologico da peçonha de Bothrops erythromelas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1991

RESUMO

B. elythromelas is a snake found exc1usivelyin the Northeast of Brazil (from Bahia to Ceará). In this Thesis, some of the biochemical and pharmacological characteristics of this venom were examined. B. erythromelas venom possesses coagulant activity as well as proteolytic (caseinolytic), phospholipase and TAME-esterase activities. Practionation of the venom yielded either three (Sephadex G-75) or four (Sephadex G-IOO) distinct peaks. The first peak contained primarily proteolytic and clotting activities; in the second one, TAME-esterase activity was detected (this peak was absent in the G-75 fractionation). The third peak contained phospholipase activity and in the last, no activity could be detected. B. erythromelas venom, compared with B. jararaca venom, is less toxic in mice, when given i.p.. However, this potency is inverted when the venoms are given i.m. in chicks. The effects of B. erythromelas venom on arterial blood pressure and respiration, as well as clotting time "in vivo" (anaesthetized dogs), were also examined. A bolus injection of B. Erythromelas venom (25 f-tg/kg,i.v.) induced a biphasic hypotensive response consisting of a rapid initial decrease followed by a partial recovery (early phase) which was then succeeded by a more sustained hypotension (late phase). The dose of venom used caused a 58.8% mortality. The animals died following a period of profound respiratory alterations. Independent pre-treatment of the animaIs with heparin, cellulose sulphate, NW-Nitro-L arginine methyl ester (L-NAME), indomethacin, antibothropic serum, or a combination of cellulose sulphate and indomethacin, abolished the lethality. The ear1yphase of hypotension was inhibited by cellulose sulphate as well as by heparin, while the late phase was partially inhibited (50%) by indomethacin. Pre-treatment with cellulose sulphate and indomethacin abolished the venom-induced alterations in blood pressure and respiration. These results suggest that bradykinin may be responsible for the initial hypotensive response and that vasodilatory eicosanoids, such as prostacyclin and/or prostaglandin E2 may mediate the late phase. Pre-treatment with L-NAME led to a more rapid recovery from the sustained late phase of hypotension although there was no effect on the immediate hypotensive response. This observation suggests that nitric oxide release, from endothelial cells, may contribute to the maintenance of the venom-induced shock. On the other hand, the hemostatic alterations were prevented only by pre-treatment with antibothropic serum, however in a dose 30 fold above that recommended by the Butantan Institute

ASSUNTO(S)

farmacologia cobra venenosa

ACESSO AO ARTIGO

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