Feldman R D, Christy J P, Paul S T, Harrison D G
Department of Internal Medicine and Pharmacology, University of Iowa College of Medicine, Iowa City 52242.
Am J Physiol. 1989 Nov;257(5 Pt 2):H1634-9. doi: 10.1152/ajpheart.1989.257.5.H1634.
The present studies were performed to examine the role of beta-adrenergic receptors in modulating smooth muscle tone in mature coronary collaterals. To examine the beta-adrenergic receptor population present, radioligand binding-cover slip autoradiographic studies were performed on sections of native canine coronary vessels and sections of coronary collaterals developed after placement of Ameroid constrictors. Specific binding of the nonselective beta-adrenergic antagonist [125I]iodopindolol to vascular smooth muscle in segments of both collaterals and native coronary arteries was saturable and stereospecific. Maximal binding and the potency of beta-adrenergic subtype-selective antagonists were similar in all segments. Beta-adrenergic relaxation of native coronary vessels and collateral vessels were studied in isolated organ chambers after preconstriction with prostaglandin F2 alpha. Both native coronary arteries and collateral segments demonstrated beta-adrenergic-mediated relaxation with affinities for both agonists and antagonists compatible with a mixed population of beta 1- and beta 2-adrenergic receptors. These studies indicate that during development, the new collateral vascular smooth muscle expresses a functional population of beta-adrenergic receptors, comparable to that in native vessels.
进行本研究以检验β-肾上腺素能受体在调节成熟冠状动脉侧支平滑肌张力中的作用。为检测存在的β-肾上腺素能受体群体，对天然犬冠状动脉切片以及放置阿梅里德缩窄器后形成的冠状动脉侧支切片进行了放射性配体结合-盖玻片放射自显影研究。非选择性β-肾上腺素能拮抗剂[125I]碘吲哚洛尔对侧支和天然冠状动脉段血管平滑肌的特异性结合是可饱和且立体特异性的。所有段中β-肾上腺素能亚型选择性拮抗剂的最大结合量和效价相似。在用前列腺素F2α预收缩后，在离体器官腔室中研究了天然冠状动脉和侧支血管的β-肾上腺素能舒张作用。天然冠状动脉和侧支段均表现出β-肾上腺素能介导的舒张作用，对激动剂和拮抗剂的亲和力与β1和β2肾上腺素能受体的混合群体一致。这些研究表明，在发育过程中，新形成的侧支血管平滑肌表达了与天然血管中相当的功能性β-肾上腺素能受体群体。
