α-Adrenoceptors and vascular regulation: Molecular, pharmacologic and clinical correlates

This manuscript is intended to provide a comprehensive review of the α-adrenoceptors (APs) and their role in vascular regulation. The historical development of the concept of receptors and the division of the α-ARs into α₁ and α₂ subtypes is traced. Emphasis will be placed on current understanding of the specific contribution of discrete α₁- and α₂-AR subtypes in the regulation of the vasculature, selective agonists and antagonists for these receptors, the second messengers utilized by these receptors, the myoplasmic calcium pathways activated to initiate smooth muscle contraction, as well as the clinical uses of agonists and antagonists that work at these receptors. New information is presented that deals with the molecular aspects of ligand interactions with specific subdomains of these receptors, as well as mRNA distribution and the regulation of α₁- and α₂-AR gene transcription and translation.