Aspects on receptor regulation and isoreceptor identification.

The present paper introduces a classification of receptor regulation. This classification takes into consideration especially the type of regulation (homoregulation vs. heteroregulation) and the biochemical mechanisms subserving the regulation process. Furthermore, criteria for isoreceptor identification are introduced on a quantitative basis, that is by means of comparisons of ED50 values obtained, using a certain agonist, for the different responses triggered by the binding of the ligand with the respective class of receptors. Finally, a possible case of isoreceptor interconversion is extensively discussed and a model for such an interconversion is suggested.