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Effect of ring fluorination of epinephrine on its cardiovascular adrenoceptor activities
A S Bass1, J D Kohli, A Adejare
1Department of Pharmacological and Physiological Sciences, The University of Chicago, IL 60637.
Abstract:
Effects of fluorine (F) substitution on the 2- and 6-positions of the catechol ring of epinephrine (Epi) on its alpha- and beta-adrenoceptor agonist activities were studied in anesthetized dogs. Increments in heart rate and contractile force were used as measures of beta 1-adrenoceptor activity, while increases and decreases in blood pressure and decreases and increases in femoral blood flow were used as measures of alpha- and beta 2-adrenoceptor activities, respectively. F substitution on the 2- and 6-positions of the catechol ring yielded compounds with opposite receptor selectivities: 2-FEpi was a selective beta-adrenoceptor agonist with little agonist activity at alpha-adrenoceptors, while the 6-F analog was a selective a-adrenoceptor agonist with no significant beta-adrenoceptor effects. Of added significance, 2-FEpi was more potent than Epi as a beta 1-adrenoceptor agonist, while 6-F Epi was more potent than the parent compound as an alpha-adrenoceptor agonist. The possible mechanisms for the effects of ring fluorination on the adrenoceptor activities of Epi and other sympathomimetic amines are discussed.
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