RESUMO
This study aimed to observe the effects of prilocaine chloridate (P) and the associations of P with felypressin (P+F), and epinephrine (P+E) on the heart rate and force of contraction on the isolated hearts of rats. The hearts were perfused according to Langendorff's method. The experiments were performed with the following substances: prilocaine (P), felypressin (F), and epinephrine (E). P was used in doses of 1.25, 2.5, and 5.0 mg. The same doses of F and P (1.0, 1.5 and 3.0 microg) were used in association with the P, respectively. Right after the application of the three doses of P, a reduction in the force of contraction was observed, with higher intensity at a higher dose, which led to cardiac arrest. A similar result was obtained with the administration of the three associations of P+F. Also the application of the three associations P+E resulted in a reduction of the force of contraction, that was, however, less intense with the associations of 1.25 mg P + 1.0 microg E and 2.5 mg P+1.5 microg E, as compared to the same doses of P alone and P+F. The two higher doses of P and P+F on the heart rate elicited a significant reduction in relation to the control, but with the associations of P+E no alterations were observed, with any one of the doses used. The results obtained in the present study suggest that an association of P and E must be used in local anesthesia, since epinephrine may well protect the heart from the depressive effects of the anesthetic salts.
