title: Vasorelaxing action of melatonin in rabbit basilar artery.
abstract: 1. In rabbit basilar arteries, melatonin (10(-5)-10(-3) M) and nifedipine (10(-10)-10(-8) M) inhibited the responses to KCl and 5-hydroxytryptamine. 2. Melatonin or nifedipine inhibited the Ca2+-responses in a Ca2+-free medium containing KCl (40 mM) or 5-HT (10(-5) M). 3. A combined treatment with nifedipine and melatonin caused no further inhibition of the Ca2+ response in the presence of K+ as compared to a single treatment with melatonin. 4. However, the combined treatment caused a greater inhibition of the Ca2+-response in the presence of 5-HT than the single treatment with either agent. 5. These results suggest that melatonin and nifedipine inhibit the same Ca2+ channels activated by KCl. Further, 5-HT-activated Ca2+ channels which are inhibited by melatonin may be different from nifedipine-sensitive Ca2+ channels activated by 5-HT.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Hawaii, Honolulu 96822.
authors.forename: S
authors.initials: S
authors.lastname: Shibata
authors.forename: N
authors.initials: N
authors.lastname: Satake
authors.forename: T
authors.initials: T
authors.lastname: Takagi
authors.forename: H
authors.initials: H
authors.lastname: Usui
mesh_terms: D000818:Animals; D001488:Basilar Artery / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology
chemical_list: D012701:Serotonin; D011189:Potassium Chloride; D009543:Nifedipine; D008550:Melatonin