[Effect of ropivacaine on neuronal norepinephrine reuptake in smooth muscle.].
OBJECTIVE
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 microg.mL-1 potentiated maximum norepinephrine effect (Emax) in 47% and 35%, respectively, while higher concentrations (50 or 100 microg.mL-1) inhibited its maximum effect. In isolated vas deferens of rats treated with reserpine, ropivacaine (10 or 20 microg.mL-1) potentiated (150% and 25%, respectively) norepinephrine-induced contractions, while higher concentrations (50 or 100 microg.mL-1) have not changed responses to norepinephrine.


CONCLUSIONS
Ropivacaine blocks neuronal norepinephrine reuptake by sympathetic nerve terminals.
Martins
Carlos Alberto de Souza
CA
Disciplina de Farmacologia, UFMA.
Aragão
Pedro Wanderley de
PW
Freire
Sonia Maria de Farias
SM
Martins
Mahiba Mattar Rahbani de Souza
MM
Borges
Marilene Oliveira da Rocha
MO
Borges
Antonio Carlos Romão
AC