Role of alpha(2)-adrenergic receptors in hypertension

This is a brief review of a series of experiments conducted over the past t wo decades, exploring the role of the cr, adrenergic receptors (alpha (2)-A R) in salt-induced hypertension. The data suggest that salt loading alters the activity of central alpha (2)-AR, resulting in a hypertensive hyperadre nergic state. Studies to separate the role of each alpha (2)-AR subtype (al pha (2A), alpha (2B), and alpha (2C)) have used genetically engineered mice with disrupted genes for each subtype, or gene treatment in rats with anti sense-oligodeoxynucleotides targeting a specific gene sequence. Taken toget her, the results of these studies indicate that the alpha (2A)-AR is centra lly predominant and exerts a tonic sympathoinhibitory function, whereas per ipherally it has a vasoconstrictive effect; the alpha (2B)-AR is responsibl e for the central hypertensive sympathoexcitatory response to salt, but is not expressed on vascular wall structures; and the alpha (2C)-AR seems to h ave no hemodynamic function. (C) 2001 American Journal of Hypertension, Ltd .