TEMPERATURE COEFFICIENTS OF AFFINITY CONSTANTS FOR THE BINDING OF ANTAGONISTS TO MUSCARINIC RECEPTORS IN THE RAT CEREBRAL-CORTEX

The temperature coefficients of binding of a series of muscarinic antagonists to their receptors in membrane preparations from the rat cerebral cortex has been examined. At 37°C the affinity constants agree with those determined by antagonism of acetylcholine‐induced contractions of the guinea‐pig ileum. The temperature‐dependence of the affinity constants is low; for the antagonists examined, the affinity constants at 0°C differ by less than a factor of 3 from those measured at 37°C. There are qualitative similarities between the estimates of the temperature coefficient of binding of the antagonists to receptors in ileum strips and in the cerebral cortex. 1979 British Pharmacological Society