INTRODUCTION:
Ropivacaine (ROPI) 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 (LIDO) and evaluate the possible involvement of the vascular endothelium induced by ROPI in isolated rat mesenteric artery ring response.
MATERIAL AND METHOD:
It was used 12 male Wistar rats (250-300g). 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.
RESULT:
Both the LIDO as ROPI showed no vasoconstrictor effect on the basal tone of rings with functional endothelium. However, when the rings were precontracted with phenylephrine, both drugs were able to induce concentration-dependent vasorelaxation (Emax = 31.7 ± 3.3%, n = 6 for LIDO and 69 ± 8%, n = 6 for ROPI) that were not altered after removal of the endothelium (Emax= 28.7 ± 1.3%, n = 7 for LIDO and Emax = 58.8 ± 5.9%, n = 6 for ROPI). In rings without functional endothelium and precontracted with depolarizing Tyrode solution (80 mM KCl), the LIDO-induced vasorelaxation was no significantly changed (Emax = 29 ± 3%, n = 7). However, ROPI-induced vasorelaxation was reduced in this protocol and the presence of 1 mM tetraethylammonium (TEA) (Emax = 21.2 ± 5.1%, n = 7 and Emax = 17.4 ± 3.7, n = 4, respectively).
CONCLUSION:
ROPI produces vasorelaxant effect in rat superior mesenteric artery, which is independent of the participation of the endothelium. This effect seems to involve K+ channels in vascular smooth muscle cell.
Ropivacaine; vasorelaxation; artery mesenteric
