EL DROPERIDOL INTERACTUA CON RECEPTORES SEROTONERGICOS Y ADRENOCEPTORES α-CARDIOVASCULARES

The purpose of the present study was to determine whether the peripheral serotonergic receptors contribute to explain the cardiovascular effects of droperidol. The effects of droperidol on the presser or chronotropic responses elicited by continuous intravenous infusion of either noradrenaline (NA; 1 μg.kg^-1.min^-1), angiotensin II (1 μg.kg^-1.min^-1) on the serotonergic agonist quipazine (100 g.kg^-1.min^-1) were studied in pithed rats. Droperidol (0.01 μ to 1 mg.kg^-1 i.v.) reversed the pressor effects of both NA or quipazine in a dose-related manner. Intravenous pretreatment with propranolol, brompheniramine or atropine (1 mg.kg^-1; each) did not alter droperidol depressive effects. On the other hand, neither the pressure response to angiotensin II nor the chronotropic effects of pressor drugs were significantly affected by droperidol. In other experiments, similar hypotensive effects of droperidol ID₅₀ 141 μg/kg; CL 105-191) and the selective 5-HT₂ blocker ketanserine (ID₅₀ 110 μg/kg; CL 91-132) on quipazine-induced pressor responses, were obtained; however, no significative change was observed with prazosin (α₁-selective blocker). These results confirm that droperidol-induced hypotension can be attributed to its α-adrenergic blocking properties, and suggest a potential interaction of droperidol with serotonin at the level of vascular receptors.