title: The desensitizing interaction of hexafluorenium with the cholinergic receptor in the diaphragm of the rat.
abstract: 1. The interaction of hexafluorenium with acetylcholine, carbachol and suxamethonium with regard to the depolarization of the end-plate of rat diaphragm was studied. The depolarization was measured with the moving meniscus technique of Fatt. The competitive antagonist d-tubocurarine was included in the studies. 2. Hexafluorenium inhibited acetylcholinesterase in the end-plate. 3. The receptors in the end-plate were desensitized by carbachol and suxamethonium. Hexafluorenium enhanced the desensitization by suxamethonium. d-Tubocurarine had no direct influence on desensitization 4. The desensitization of the receptors in rat diaphragm is compatible with a cyclic model of desensitization. 5. The desensitizing interaction of hexafluorenium with the receptors may explain the non-competitive antagonism with depolarizing drugs with regard to the depolarization of the end-plate and the synergism with these drugs with regard to the paralysis of the indirectly stimulated muscle reported earlier. 6. The affinities of carbachol, suxamethonium and d-tubocurarine to the sensitive receptors are 4.9, 5.2 and 6.8, respectively.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D003964:Diaphragm / Q000187:drug effects; D005449:Fluorenes; D006584:Hexamethonium Compounds / Q000494:pharmacology*; D066298:In Vitro Techniques; D009045:Motor Endplate / Q000187:drug effects; D009467:Neuromuscular Depolarizing Agents; D051381:Rats; D011950:Receptors, Cholinergic / Q000187:drug effects*; D013390:Succinylcholine / Q000494:pharmacology
chemical_list: D005449:Fluorenes; D006584:Hexamethonium Compounds; D009467:Neuromuscular Depolarizing Agents; D011950:Receptors, Cholinergic; C005034:hexafluorenium; D002217:Carbachol; D013390:Succinylcholine; D000109:Acetylcholine