from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A site in the autonomic nervous system in which excitatory responses occur when adrenergic agents, such as norepinephrine and epinephrine, are released. Activation of alpha-receptors causes various physiological reactions, including the stimulation of associated muscles and the constriction of blood vessels.
Sorry, no etymologies found.
I was convinced that the histamine antagonists of the day were analogous to the alpha-receptor antagonists and that the equivalent of a beta-receptor antagonist was needed to block, for example, histamine-stimulated acid secretion.