Abstract

Experiments have been carried out to characterize further the autoinhibitory phenomenon which follows contact of rabbit aortic strips with epinephrine. Desensitization was found to occur after exposure to very low concentrations of the catecholamines. The time course of recovery from inhibitory contacts with different concentrations of epinephrine was such as to predict that autoinhibition would generally he a significant factor in modifying experimental determinations of dose-response relationships. This was found to be the case, and a graphical method, leading to drug-effect hysteresis loops, is proposed as a means of assessing the degree of participation of this factor in a given experimental situation.