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.
ANESTHESIA; ANESTHETICS; ANESTHETICS; AUTONOMOUS NERVOUS SYSTEM
