Alpha‐adrenergic receptors in human blood vessels.

Abstract

The evidence for the presence of postjunctional alpha 1‐ and alpha 2‐ adrenoceptor subtypes in human blood vessels is reviewed. Experiments in healthy subjects are described that show that alpha 1‐ as well as alpha 2‐adrenoceptor mediated vasoconstriction contribute to vascular smooth muscle tone and that adrenaline and noradrenaline have similar affinities for each subtype. In addition, evidence is presented for a preferential intrajunctional location of alpha 1‐adrenoceptors and a preferential extrajunctional location of alpha 2‐adrenoceptors in human blood vessels. It is concluded that at present postjunctional alpha‐ adrenoceptors in human blood vessels can be classified as alpha 1 and alpha 2. Despite the fact that both subtypes mediate vasoconstriction, these receptors are likely to subserve different physiological functions. 1986 The British Pharmacological Society