title: Muscarinic M2 receptor synthesis: study of receptor turnover with propylbenzilylcholine mustard.
abstract: We have investigated the rate and the functional responsiveness of the newly synthesised M2 muscarinic receptors in HEL 299 cells following propylbenzilylcholine mustard treatment at 37 degrees C. Propylbenzilylcholine mustard induced a dose-dependent loss of the hydrophilic ligand [3H]N-methylscopolamine binding sites with 80% inactivation at 0.1 microM. The rate of muscarinic receptor synthesis in these cells, estimated from wash-out experiments following propylbenzilylcholine mustard treatment, was very slow and returned to control values after 36 h of propylbenzilylcholine mustard removal. The recovery of muscarinic receptors was blocked by the cycloheximide pre-treatment, indicating the synthetic pathway for the new receptors. In control cells as well as in cells treated with propylbenzilylcholine mustard and allowed to recover for 12 h, carbachol still inhibited forskolin-induced cAMP accumulation. These results show that (i) the rate of M2 muscarinic receptor synthesis is slow (ii) the recovery of receptors is mainly through increased synthesis and (iii) the newly synthesised receptors retain their full functional activity.
authors.affiliation: Department of Thoracic Medicine, National Heart and Lung Institute, London, UK.
authors.forename: E B
authors.initials: EB
authors.lastname: Haddad
authors.forename: J
authors.initials: J
authors.lastname: Rousell
authors.forename: P J
authors.initials: PJ
authors.lastname: Barnes
mesh_terms: D000478:Alkylation; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D019832:N-Methylscopolamine; D011438:Propylbenzilylcholine Mustard / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000096:biosynthesis* / Q000187:drug effects; D012602:Scopolamine Derivatives / Q000378:metabolism
chemical_list: D018727:Muscarinic Antagonists; D011500:Protein Synthesis Inhibitors; D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D005576:Colforsin; D011438:Propylbenzilylcholine Mustard; D003513:Cycloheximide; D000242:Cyclic AMP; D019832:N-Methylscopolamine