Investigations of the subtype of alpha 2-adrenoceptor mediating contractions of the human saphenous vein

• Published in: British journal of pharmacology 1992-06, Vol.106 (2), p.447-451
• Main Authors: Smith, K, Connaughton, S, Docherty, J R
• Format: Article
• Language: English
• Subjects: Adrenergic alpha-Antagonists - pharmacology; Adult; Animals; Blood Platelets - drug effects; Female; Humans; In Vitro Techniques; Isometric Contraction - drug effects; Male; Middle Aged; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - physiology; Radioligand Assay; Rats; Rats, Wistar; Receptors, Adrenergic, alpha - drug effects; Receptors, Adrenergic, alpha - physiology; Saphenous Vein - drug effects; Saphenous Vein - physiology
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.1992.tb14354.x

1. We have examined the effects of a series of alpha 2-adrenoceptor antagonists against isometric contractions to noradrenaline in human saphenous vein, and correlated these potencies with affinities for the alpha 2A-ligand binding site of human platelet and the alpha 2B-ligand binding site of rat kidney. 2. The alpha 2B-selective adrenoceptor antagonists, prazosin, ARC 239 and HV 723 showed high, and the alpha 2A-selective antagonist BRL 44408 showed low, potency in human saphenous vein. 3. Potency in human saphenous vein correlated better with affinity for the alpha 2B-ligand binding site (r = 0.71, n = 12, P less than 0.01) than with affinity for the alpha 2A-ligand binding site (r = 0.56, n = 12, non significant). 4. It is concluded that the postjunctional alpha 2-adrenoceptor of human saphenous vein resembles an alpha 2B-ligand binding site more than an alpha 2A-ligand binding site.