Affinity and efficacy correlate with chemical structuremore than potency does in a series of pentatomic cyclicmuscarinic agonists

1 The efficacy and affinity of nine pentatomic cyclic muscarinic agonists were determined on theguinea-pig ileum, according to the method of Furchgott & Bursztyn {1967). 2 Tbe efficacy and affinity of these agonists are affected differently by structural modifications.3 Our results suggest that a strong dipole oriented in the same direction as that of the hydroxy groupof muscarine, or the presence of a polarizable atom in the same position, are important for efficac