β-Adrenoceptor (b-AR) located on blood vessel smooth muscle cells mediates vasorelaxing effects of its agonists including endogenous catecholamines. Early pharmacological studies classified the major vascular β-AR subtype into β2-AR vs. β1-AR in cardiac muscle. However, additional later studies have demonstrated a substantial role for non-β2-AR subtypes including β1-AR as functional β-ARs in the vasculature. Recent reports also elucidate a contribution of β3-AR, a non-β1-/β2-AR subtype, to blood vessel relaxant responses. In the present article, we review the distribution of β-AR subtypes in blood vessel smooth muscles and reexamine their physiological significances. We also describe possible roles for vascular endothelium in β-AR mediated relaxation of blood vessels.
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