title: alpha(1)-Adrenergic receptor subtypes in rat cerebral microvessels.
abstract: To identify alpha(1)-adrenergic receptor subtypes involved in the regulation of cerebral microcirculation, we studied alpha(1)-adrenergic receptor subtypes expressed in the rat cerebral microvessels. The microvessels were prepared from rat cerebral cortex by albumin flotation and glass bead filtration techniques. [(125)I]HEAT binding to the cerebral microvessels was displaced by low concentrations of 5-methylurapidil, a selective antagonist for alpha(1A)-receptors, and modified Scatchard analysis of the data revealed that half of alpha(1)-receptors is alpha(1A)-subtype, and that alpha(1B)- and/or alpha(1D)-receptors are also present. The K(i) value of the high-affinity component for 5-methylurapidil was 3.90+/-1.08 nM, which is comparable with the value obtained in the rat cerebral cortex (2.17+/-0.88 nM). Reverse transcription and polymerase chain reaction experiments showed that mRNAs of alpha(1A)- and alpha(1B)-receptors, but not alpha(1D)-receptors, were expressed in the cerebral microvessels. These results suggest that alpha(1)-receptors involved in the regulation of cerebral microvessel function are alpha(1A)- and alpha(1B)-receptor subtypes.
authors.affiliation: Department of Pharmacology, Miyazaki Medical College, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yokoo
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
authors.forename: S
authors.initials: S
authors.lastname: Minami
authors.forename: S
authors.initials: S
authors.lastname: Shiraishi
authors.forename: R
authors.initials: R
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Yanagita
authors.forename: K
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: M
authors.initials: M
authors.lastname: Mohri
authors.forename: A
authors.initials: A
authors.lastname: Wada
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D001808:Blood Vessels / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology; D020033:Protein Isoforms / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011942:Receptors, Adrenergic, alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D000317:Adrenergic alpha-Antagonists; D010879:Piperazines; D020033:Protein Isoforms; D012333:RNA, Messenger; D011942:Receptors, Adrenergic, alpha; C057446:5-methylurapidil