Differences in the applicability of the easson-stedman hypothesis to the alpha 1- and alpha 2-adrenergic effects of phenethylamines and imidazolines.

The enantiomers of 2-(3,4, alpha-trihydroxybenzyl)imidazoline and the corresponding desoxy derivative, 2-(3,4-dihydroxybenzyl)imidazoline, were evaluated at alpha 1- and alpha 2-adrenergic receptors to test the applicability of the Easson-Stedman hypothesis to the imidazoline class of alpha-adrenergic agonists. A series of closely related phenethylamines was included for comparison. The Easson-Stedman hypothesis states that optically active adrenergic agonists possessing an asymmetric hydroxyl-substituted benzylic carbon atom will have the following relative potencies: R(-) greater than S(+) = desoxy. While the phenethylamines were found to adhere to the Easson-Stedman hypothesis at both alpha 1- and alpha 2-adrenergic receptors, the optically active imidazolines did not. These findings further support our previous observations that the phenethylamines and imidazolines may interact differently with alpha-adrenergic receptors.