Cardiovascular tryptamine receptors in the chicken

The effects of "M"-receptor blockers (atropine and morphine), "D"-receptor blockers (dibenamine, dibenzyline, methysergide) and a ganglion blocking agent (mecamylamine) were studied to characterize cardiovascular tryptaminergic receptors in domestic fowl. This study showed the presence of both "M" and "D" tryptaminergic receptors (both mediating systemic hypotension) and also other "D"-receptors, which mediate arterial and venous hypertensive responses to 5-HT. There appear to be interactions of tryptaminergic, cholinergic and adrenergic mechanisms in the mediation of cardiovascular responses to 5-HT in chicken.