“Droperidol (3 X 10(-7) M - …) M), cyproheptadine (10(-7) M), and diphenhydramine (10(-7) M) prolonged the relaxation and … the amplitude of the contraction produced by Gb (400 micrograms/ml), whereas phentolamine, hexamethonium, methysergide, or cimetidine (10(-7) … 10(-6) M) did not affect the response to Gb.”