alpha-Receptors, Adrenergic

One of the two major pharmacological subdivisions of Adrenergic Receptors that were originally defined by the relative potencies of various adrenergic compounds. The alpha receptors were initially described as excitatory receptors that post-junctionally stimulate SMOOTH Muscle Contraction. However, further analysis has revealed a more complex picture involving several alpha receptor subtypes and their involvement in Feedback Regulation.