Effects of VA-045, a novel apovincaminic acid derivative, on rabbit basilar artery.
We investigated the effects of VA-045, an apovincaminic acid derivative, on isolated basilar artery of the rabbit. In basilar artery precontracted with histamine (10(-6) M), VA-045 (10(-9) to 10(-5) M) produced a concentration-dependent relaxation, but VA-045-induced relaxation was significantly reduced when the tonus of the mesentery was raised by isotonic high K+ (30 or 65 mM) or histamine (10(-6) M) with 15 mM K+. VA-045-induced relaxations of the basilar artery were not affected by 10 mM tetraethylammonium (TEA), 10(-6) M 4-aminopyridine, 10(-6) M charybdotoxin, 10(-7) M apamin and 10(-6) M glybenclamide. VA-045-induced relaxation was not influenced by 10(-5) M methylene blue. These results suggest that increased open probability of potassium channels, which are not Ca(2+)-dependent K(+)-channels or TEA- or ATP-sensitive K(+)-channels, may be involved in VA-045-induced relaxation of basilar artery.
Yamada
S
S
Nihon Bioresearch Center Inc., Gifu, Japan.
Okuyama
S
S
Kamata
K
K
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects* / Q000502:physiology; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007552:Isotonic Solutions; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects; D011817:Rabbits; D014665:Vasodilator Agents / Q000494:pharmacology*; D014748:Vinca Alkaloids / Q000494:pharmacology*
D007552:Isotonic Solutions; D015221:Potassium Channels; D014665:Vasodilator Agents; D014748:Vinca Alkaloids; C081044:2-(nitrooxy)ethyl apovincaminate; D006632:Histamine; D011188:Potassium