Different sensitivity of beta 1- and beta 2-adrenergic receptors towards cyanogen bromide

beta 1-Adrenergic receptors of turkey and beta 2-receptors of rat erythrocyte membranes were identified by (-)-[3H]-dihydroalprenolol ([3H]-DHA) binding. Treatment of these membranes with the reagent cyanogen bromide causes a concentration dependent decrease in the number of binding sites, without affecting the affinity of the tracer. Whereas inactivation of the beta 1-receptors is not affected by the pH (between pH 6 and 9), substantial inactivation of the beta 2-receptors takes place only under mild acidic conditions. The ability of CNBr (cyanogen bromide) to discriminate between both receptor subclasses at basic pH is also confirmed for rat heart membranes (beta 1-receptors), Friend erythroleukemia and S49 lymphoma cell membranes (beta 2-receptors).