Droperidol interacts with vascular serotonin receptors and alpha-adrenoceptors.
This investigation was performed to determine whether droperidol interacts with 5-hydroxytryptamine (serotonin) receptors in the rat aorta. Droperidol caused concentration-dependent vasorelaxation in endothelium-intact and endothelium-denuded aortic rings precontracted with noradrenaline or 5-hydroxytryptamine. Conversely, the contractile effect of prostaglandin F2 alpha was not affected by droperidol. Pretreatment with propranolol, brompheniramine and atropine (10(-6) M each) did not alter the relaxant effects of droperidol. In addition, droperidol shifted the 5-hydroxytryptamine and noradrenaline concentration-response curves to the right in an apparently competitive manner. However, prazosin did not modify the concentration-response curve to 5-hydroxytryptamine, which is consistent with the hypothesis that the latter has an intrinsic efficacy for non-alpha 1-adrenoceptors. These results strongly suggest that a direct arterial endothelium-independent relaxant action of droperidol can be attributed to a 5-hydroxytryptamine receptor-blocking property and support its vascular alpha-adrenoceptor-blocking effect.
Castillo
C
C
Departamento de Fisiología y Farmacología de la Escuela Superior de Medicina, Tomás, México.
Castillo
E F
EF
Valencia
I
I
Ibarra
M
M
Bobadilla
R A
RA
D000818:Animals; D001011:Aorta / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004329:Droperidol / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D011985:Receptors, Serotonin; D012701:Serotonin; D004329:Droperidol; D009638:Norepinephrine