Role of K+ channels in neuropeptide Y-induced vasoconstriction in rabbit cerebral basilar artery.
The role of K+ channels in the direct vasoconstrictive response induced by neuropeptide Y was investigated in isolated basilar arteries of rabbits and in vivo in rats. K+ channel openers, either BRL38227 or diazoxide, caused dose-dependent and complete relaxation of isolated arteries precontracted by neuropeptide Y. Exposure to both BRL38227 and diazoxide shifted the concentration-response curves for neuropeptide Y to the right without changing the maximal response. However, BRL38227 antagonized the angiotensin II-induced vasoconstriction noncompetitively. In vivo, the pressor responses produced by neuropeptide Y were significantly inhibited by pretreatment with BRL38227 in anesthetized rats. These results show that K+ channel openers antagonize neuropeptide Y-induced vasoconstriction in a competitive manner and suggest that blockade of K+ channels contributes, at least in part, to the direct vasoconstrictive effect of neuropeptide Y.
Institute of Vascular Medicine, Third Hospital, Beijing Medical University, People's Republic of China.
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Xia
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Han
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects; D001578:Benzopyrans / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D019806:Cromakalim; D003981:Diazoxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009478:Neuropeptide Y / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011758:Pyrroles / Q000494:pharmacology; D011817:Rabbits; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D001578:Benzopyrans; D009478:Neuropeptide Y; D015221:Potassium Channels; D011758:Pyrroles; D014662:Vasoconstrictor Agents; D019806:Cromakalim; D003981:Diazoxide