Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942005000500008
Brazilian Journal of Anesthesiology
Scientific Article

Efeito da ropivacaína na recaptação neuronal de noradrenalina em músculo liso

Effect of ropivacaine on neuronal norepinephrine reuptake in smooth muscle

Carlos Alberto de Souza Martins; Pedro Wanderley de Aragão; Sonia Maria de Farias Freire; Mahiba Mattar Rahbani de Souza Martins; Marilene Oliveira da Rocha Borges; Antonio Carlos Romão Borges

http://dx.doi.org/10.1590/S0034-70942005000500008 Braz J Anesthesiol, vol.55, n5, p.532-537, 2005
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Resumo

JUSTIFICATIVA E OBJETIVOS: Além da ação anestésica local, a ropivacaína apresenta efeito vasoconstritor, clinicamente significativo, que pode ser observado quando da anestesia infiltrativa, o que a torna um anestésico importante no bloqueio de campo. Este trabalho teve por objetivo caracterizar o mecanismo de ação constritora da ropivacaína em músculo liso. MÉTODO: Em preparações isoladas de ducto deferente de ratos foram construídas curvas concentração-efeito de noradrenalina na ausência ou na presença da ropivacaína. Em outra série de experimentos os ratos foram tratados com reserpina (10 mg.kg-1, por via intraperitoneal) para avaliar a reatividade dos ductos deferentes à tiramina ou noradrenalina, na ausência ou presença da ropivacaína. RESULTADOS: A ropivacaína nas concentrações de 5 ou 10 µg.mL-1 potencializou o efeito máximo (Emax) da noradrenalina em 47% e 35%, respectivamente, enquanto que nas concentrações de 50 ou 100 µg.mL-1 inibiu o efeito máximo produzido por este agonista. Em ductos deferentes isolados de ratos reserpinizados, a ropivacaína (10 ou 20 µg.mL-1) potencializou (150% e 25%, respectivamente) as contrações induzidas pela noradrenalina, enquanto que as concentrações de 50 ou 100 µg.mL-1 não alteraram as respostas à noradrenalina. CONCLUSÕES: Os resultados obtidos permitem concluir que a ropivacaína bloqueia a recaptação neuronal de noradrenalina pelos terminais nervosos simpáticos.

Palavras-chave

ANESTESIA, ANESTÉSICOS, ANESTÉSICOS, SISTEMA NERVOSO AUTÔNOMO

Abstract

BACKGROUND AND OBJECTIVES: In addition to local anesthetic action, ropivacaine has clinically significant vasoconstrictor effects, which may be observed at infiltrative anesthesia, making it an important anesthetic for field blockade. This study aimed at characterizing the constrictor mechanism of ropivacaine on smooth muscles. METHODS: Norepinephrine concentration-effect curves in the absence or presence of ropivacaine were plotted on isolated preparations of vas deferens of rats. In another series of experiments rats were treated with reserpine (10 mg.kg-1, i.p.) to evaluate vas deferens reactivity to tyramine or norepinephrine, in the absence or presence of ropivacaine. RESULTS: Ropivacaine 5 or 10 µg.mL-1 potentiated maximum norepinephrine effect (Emax) in 47% and 35%, respectively, while higher concentrations (50 or 100 µg.mL-1) inhibited its maximum effect. In isolated vas deferens of rats treated with reserpine, ropivacaine (10 or 20 µg.mL-1) potentiated (150% and 25%, respectively) norepinephrine-induced contractions, while higher concentrations (50 or 100 µg.mL-1) have not changed responses to norepinephrine. CONCLUSIONS: Ropivacaine blocks neuronal norepinephrine reuptake by sympathetic nerve terminals.

Keywords

ANESTHESIA, ANESTHETICS, ANESTHETICS, AUTONOMOUS NERVOUS SYSTEM

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