Characteristic localization of alpha 1- and alpha 2-adrenoceptors in the human kidney.

1. The localization of alpha-adrenoceptors in the plasma membranes of human kidney were investigated by radioligand binding, using an alpha 1-antagonist, [3H]-bunazosin, and an alpha 2-antagonist, [3H]-rauwolscine. 2. Both the maximum binding (Bmax) and dissociation constant (Kd) of [3H]-bunazosin were greater in the cortex than in the medulla. The Bmax of [3H]-rauwolscine in the medulla was greater than in the cortex. 3. Thus, alpha 1-adrenoceptors appeared to be localized predominantly in the cortex, while the alpha 2-adrenoceptors were mainly present in the medulla of the human kidney.