Molecular pharmacology of human alpha(1)-adrenergic receptors: Unique features of the alpha(1a)-subtype

alpha(1)-Adrenergic receptors (alpha(1)ARs) are G protein-coupled receptors important in the dynamic component of benign prostatic hyperplasia. alpha( 1)ARs stimulate predominantly phospholipase C-beta, resulting in mobilizati on of calcium from intracellular stores and, ultimately, smooth muscle cont raction, cDNAs encoding three human alpha(1)ARs (alpha(1a), alpha(1b), alph a(1d)) have been cloned, expressed stably in cells, and characterized pharm acologically. Extensive species heterogeneity in tissue distribution emphas izes the importance of studying alpha(1)ARs in human tissues. Because of th e important role of alpha(1a)ARs in mediating prostate smooth muscle contra ction, this current review describes al, carboxyl terminal splice variants, examines alpha(1)AR subtype distribution in various tissues and the role o f the putative alpha(1L)AR in human prostate, provides a brief discussion r egarding regulation of this receptor by agonist, and finally discusses impl ications of distinct alpha(1)AR subtype distribution in human bladder compa red with prostate.