Antagonism of the responses to isoproterenol in the rat hippocampal slice with subtype-selective antagonists

The electrophysiological and cAMP responses to the β-adrenoceptor agonist isoproterenol were measured in the in vitro hippocampal slice preparation. Subtype-selective antagonists were used to evaluate the specificity of these responses. The β₁-selective antagonist ICI 89,406 was 60-fold more potent than was the β₂-selective antagonist ICI 118,551 at antagonizing the electrophysiological response. ICI 89,406 was 200 times more potent in its antagonism of the cAMP response. These results suggest that the electrophysiological and cAMP responses in this preparation are primarily mediated by β₁-adrenoceptors.