Alpha1 adrenergic receptor blockade in the male lower urinary tract and other body systems

Recent developments in pharmacology and molecular cloning techniques have led to an increased interest in the therapeutic potential of drugs which act via alpha adrenoceptors. Of particular interest are the alpha 1 adrenoceptors. Pharmacologically, two subtypes of the alpha 1 adrenoceptor have been characterised, namely alpha 1A and alpha 1B. Three subtypes with high affinity for selective alpha 1 adrenoceptor antagonists have also been cloned, that is the alpha 1b, alpha 1c and alpha 1a/d subtypes. Selective alpha 1 adrenoceptor antagonists have become an accepted treatment alternative in the management of both benign prostatic hyperplasia and hypertension, based on their ability to inhibit alpha 1 adrenoceptors of the lower urinary tract and cardiovascular system. Central actions may also be apparent. While cloned receptors of the prostatic stroma seem to be of the alpha 1c subtype, none of the adrenoceptor antagonists available today is subtype selective. This paper will discuss the characterization and localization of the different alpha 1 adrenoceptors and the therapeutic implications of inhibition.