High gender -specific susceptibility to curare- a neuromuscular blocking agent

Curare, a selective skeletal muscle relaxant, has been used clinically to reduce shivering and as an anesthetic auxiliary in abdominal surgery. It is also widely used in animal experiments to block neuromuscular junction activity. Effective doses of curare diminish muscle contraction without affecting brain function, but at higher doses it is known to be lethal. However, the exact dose of curare initiating muscle relaxation vs. lethal effect has not been fully characterized in mice. In this study we carefully examined the dose-response for achieving muscle inactivity over lethality in both male and female mice (C57BL6/J). The most striking finding of this study is that female mice were highly susceptible to curare; both the EDm and LDm were at least 3-fold lower than male littermates. This study shows that gender-specific differences can be an important factor when administering skeletal muscle relaxants, particularly curare or other analogous agents targeted to the neuromuscular junction.

Empleo del curare como cebado del atracurio / Employ of curare how atracurium priming

Veintitrés pacientes ASA I y II a quienes se les practicaría cirugía electiva y además estaba indicado el uso de relajantes musculares no despolarizantes e intubación traqueal, los cuales se anestesiaron con Enflurano (1 CAM espiratotio), fueron asignados aleatoriamente para recibir, bien 250 ug/kg de Atracurio en forma de Bolus ó 50 ug/kg de d'Tubocurarina tres minutos antes de 150 ug/kg de Atracurio. El tiempo necesario para alcanzar un bloqueo del 80 por ciento fue significativamente menor en el grupo cebado con curare (p<0,001), esta droga también potencia el máximo efecto del Atracurio (p<0.01) y acorta el tiempo para lograrlo (p<0.001). El cebado en esta experiencia enlentece los índices de recuperación (no significativamente) y prolonga la duración de su efecto clínico (p<0,01). Se notó una tendencia a mejorar las condiciones para la intubación en este grupo cebado

Direct negative chronotropic and inotropic efects of curare on isolated and perfused frog's heart

It has been stated that curare has no direct effect upon the heart because the cardiac muscle is deprived of nicotine receptors. While performing an experimental work, we noticed that when high doses of curare were administered to frogs, a change in cardiac activity occurred. In order to elucidate whether the cardiac effects of curare wee the results of a direct action or a reflex response, we studie the effects of increasing doses of d-tubocurarine on the rate and contractility of 8 isolated and perfused frogs'hearts. After testing the d-tubocurarine effects on the heart rate and contractility, we added either acetylcholine, atropine, atenonol or verapamil in orden to find out whether any change ocurred in the cardiac effects produced byd-tubocurarine. Thirty seven measurements were carriet out and it wasfound that 1) high doses (between 1 and 15 micrograms) of d-tubocurarine produced a highly significant decrease in heart rate an contractility; 2) d-tubocurarine did not avoid the acetycholine effect; 3) atropine, atenonol and verapamil did not interfere with d-tubocurarine effects. We conclude that high doses of d-tubocurarine produce "dosis-dependent" heart rate and contratility reductions. These effects are not mediated by muscarinic receptors beta-1 receptors or the show calcium channels