ABSTRACT
For the chemist, the argument about receptors really goes back earlier to the work of Cushny on the difference between the isomers of atropine. The idea that there might be subtypes of receptors wasn't totally strange, but the author think the general ruling was that receptors were the same until proved different and this wasn't always easy unless the people had selective antagonists. Stephenson went to Bristol and was then recruited by Gaddum and started his well-known work on receptors. Stephenson suggested that compounds differed in their ability to activate receptors, differed in their efficacy, and that active agonists might produce a maximum response from the tissue with perhaps less than 5% of the receptors occupied. Identifying receptors depends on having antagonists and one of the problems is to get the chemists who make them to understand the pharmacologists as well as the other way round.
