TY - JOUR T1 - The Relationship between Desensitization and the Metaphilic Effect at Cholinergic Receptors JF - Molecular Pharmacology JO - Mol Pharmacol SP - 383 LP - 390 VL - 6 IS - 4 AU - H. P. RANG AU - J. M. RITTER Y1 - 1970/07/01 UR - http://molpharm.aspetjournals.org/content/6/4/383.abstract N2 - Experiments were carried out to test the possibility that the metaphilic effect seen with certain antagonists acting at cholinergic receptors in chick and frog muscle was closely related to the phenomenon of receptor desensitization. The action of the metaphilic antagonist dinaphthyldecamethonium mustard in blocking the contraction of chick biventer cervicis muscle or the end-plate depolarization in frog muscle was studied. In both tissues it was found that agonists that were particularly effective in desensitizing the receptors also produced a marked metaphilic effect. A linear relationship was found between the metaphilic effect and desensitization, which was independent of the drug used to produce the desensitization. This finding was consistent with the hypothesis that metaphilic antagonists have a preferential affinity for desensitized receptors. For the antagonist studied, the rate of alkylation appeared to be about 5 times greater for desensitized than for normal receptors. ACKNOWLEDGMENTS We are grateful to Dr. E. W. Gill and Dr. R. B. Barlow for their generosity in supplying many of the compounds used in this study. ER -