In vitro interactions of agonists and antagonists with beta-adrenergic receptors.

Neurotransmitters and hormones mediate their effects through interaction with specific receptors. A complete understanding of the effects of these chemical signals requires detailed knowledge, at the molecular level, of agonist/receptor interactions. It is likely that agonists and antagonists interact with the same site on a receptor. Agonists, however, are by definition different from antagonists in that agonists are responsible for transducing information across the cell membrane, ultimately resulting in a biological response, while antagonists appear to act through passive occupancy of receptors. Implicit in this concept is the idea that these fundamental differences between agonists and antagonists arise from the sequelae induced by agonist-specific interactions with receptors.