Avaliação dos efeitos da ropivacaína sobre a reatividade vascular em artéria mesentérica de rato

Abstract

Introduction: Ropivacaine is a local anesthetic of long duration of action, more recently introduced in medicine, however is not available for dental use in tubes yet. Clinical and animal studies have confirmed that bupivacaine is an effective anesthetic that also has an intrinsic vasoconstrictor effect. Objective: To evaluate the effects of ropivacaine on vascular reactivity in isolated rat mesenteric artery, compare this to the effect of lidocaine and evaluate the possible involvement of the vascular endothelium induced by ropivacaine in isolated rat mesenteric artery ring response. Material and Methods: It was used 12 male Wistar rats (250-300 g). The animals were euthanized and through an incision in the abdomen of the animal, the mesenteric artery was removed. Artery rings (1-2 mm) were obtained by the mesenteric artery, which were kept in vats containing 10 ml of Tyrode's nutrient solution kept at 37 ° C and gassed with carbogen. For the recording of isometric contractions, each ring was suspended by cotton lines to a force transducer connected to a data acquisition system. Results: Both lidocaine and ropivacaine have no vasoconstrictor effect when added to a vat in the basal tone of the rings with functional endothelium. In the same way they were able to induce relaxation in a concentration-dependent proportion in isolated superior mesenteric artery of rat and with functional endothelium rings pre contracted with phenylephrine (Emax = 31.7 % ± 3.3 and 69 ± 8 %, respectively ; n = 6). The vasorelaxation responses for lidocaine and ropivacaine rings without functional endothelium ( Emax = 28.7 ± 1.3 %, n = 7 Emax = 58.8 ± 5.9 %, n = 6 , respectively) were not significantly different of those obtained under the condition where the rings with functional endothelium were. Both lidocaine and ropivacaine were able to induce vasorelaxation (Emax = 29 ± 3 %, n = 7 and 21.2 ± 5.1 %, n = 7, respectively ) in the superior mesenteric artery rings isolated rat without functional endothelium however, pre contracted with depolarizing Tyrode solution ( 80 mM KCl ). Conclusion: Ropivacaine produces vasorelaxant effect in rat superior mesenteric artery, which is independent of the participation of the endothelium and possibly by opening channels for K + in vascular smooth muscle cell.