Antagonism between adenosine and bromobenzoyl-methyladamantylamine, a K+-channel blocker, in atrial myocardium of guinea pig.

The effect of bromobenzoyl-methyladamantylamine (BMA) on the adenosine-induced changes in the electrical and mechanical activity of the atrial muscle, and the effect of adenosine on the slow action potentials induced by BMA in K+-depolarized atrial myocardium of guinea pig were studied. BMA was able to antagonize the adenosine-induced shortening of the action potential duration and negative inotropic effect. This action of BMA was potentiated by theophylline, and reduced by dipyridamole. Adenosine depressed the BMA-induced slow action potentials. The results suggest that there may be an antagonism between BMA and adenosine.