Neuromuscular effect of venoms from adults and juveniles of Crotalus durissus cumanensis (Humboldt, 1811) from Guajira, Colombia.

A toxinological study was performed to compare the neuromuscular effect of venom from adult and juvenile specimens from Crotalus durissus cumanensis from Guajira, Colombia. Both venoms exhibited neurotoxic activity in chick biventer cervicis nerve-muscle preparation. In addition, venom from juveniles was faster than adults to produce a neuromuscular blockade. In the contrary to the venom from juvenile's, at high doses, adult's venom affected the ACh and KCl contractures, indicating a myotoxic effect.

Neuromuscular activity of the venoms of the Colombian coral snakes Micrurus dissoleucus and Micrurus mipartitus: an evolutionary perspective.

The venoms of coral snakes (genus Micrurus) are known to induce a broad spectrum of pharmacological activities. While some studies have investigated their potential human effects, little is known about their mechanism of action in terms of the ecological diversity and evolutionary relationships among the group. In the current study we investigated the neuromuscular blockade of the venom of two sister species Micrurus mipartitus and Micrurus dissoleucus, which exhibit divergent ecological characteristics in Colombia, by using the chick biventer cervicis nerve-muscle preparation. We also undertook a phylogenetic analysis of these species and their congeners, in order to provide an evolutionary framework for the American coral snakes. The venom of M. mipartitus caused a concentration-dependant inhibition (3-10 µg/ml) of nerve-mediated twitches and significantly inhibited contractile responses to exogenous ACh (1 mM), but not KCl (40 mM), indicating a postsynaptic mechanism of action. The inhibition of indirect twitches at the lower venom dose (3 µg/ml) showed to be triphasic and the effect was further attenuated when PLA2 was inhibited. M. dissoleucus venom (10-50 µg/ml) failed to produce a complete blockade of nerve-mediated twitches within a 3 h time period and significantly inhibited contractile responses to exogenous ACh (1 mM) and KCl (40 mM), indicating both postsynaptic and myotoxic mechanisms of action. Myotoxic activity was confirmed by morphological studies of the envenomed tissues. Our results demonstrate a hitherto unsuspected diversity of pharmacological actions in closely related species which exhibit divergent ecological characteristics; these results have important implications for both the clinical management of Coral snake envenomings and the design of Micrurus antivenom.

Estabilidad de la actividad neutralizante del antiveneno ofídico conservado a 4§C y a 16§C ontra el veneno de cascabel (Crotalus durissus cumanensis) de Colombia / Stability of the neutralizing activity of snake antivenom stored at 4§C and 16§C against Crotalus durissus cumanensis venom from Colombia

Se determinó la actividad neutralizante de la letalidad de varios lotes de antiveneno polivalente (no liofilizado), producidos por el Instituto Nacional de Salud, los cuales fueron retados contra una mezcla de venenos de cascabel (Crotalus durissus cumanensis) de Colombia. Se compara la actividad de los diferetes lotes almacenados en oscuridad a las temperaturas de 4§C y 16§C. Se estableció el porcentaje remanente de la potencia de cada lote para cada temperatura en los diferentes años a lo largo del período del estudio. Se concluye que el antiveneno almacenado en las condiciones recomendadas, mantiene casi la totalidad de la capacidad de neutralización (97.9 por ciento) luego de tres años de almacenamiento, lo que corresponde a la fecha de expiración del producto. En cambio, el antiveneno almacenado a 16§C y oscuridad, luego de dos años de almacenamiento, mantiene el 87.9 por ciento de su capacidad protectora contra veneno de cascabel, protección similar a la encontrada bajo las mismas condiciones de almacenamiento, para veneno de Taya X, pasados dos años de almacenamiento, sustentando la recomendación de descartar el producto, trascurridos dos años de almacenamiento en estas condiciones