Effects of depolarizing agents and Na+-channel inhibitors on ligand binding to muscarinic receptors from rat cerebral cortex.
In a vesicle preparation from rat cerebral cortex, carbachol recognizes a high-affinity and a low-affinity muscarinic agonist binding site. A number of agents, including veratridine (10 microM), gramicidin (10 microM) and valinomycin (10 microM), which depolarize the vesicles also appear to block the high-affinity muscarinic agonist binding site. Lowering [Na+] (from 137 to 80 mM) or raising [K+] (from 5 to 50 mM) produced effects similar to those of the depolarizing agents. Agents such as tetrodotoxin (1 microM), which block the Na+-channel, also appear to block the high-affinity agonist binding site or to convert it into a low-affinity agonist binding form.
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008024:Ligands; D008297:Male; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology*; D009861:Onium Compounds / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D007473:Ion Channels; D008024:Ligands; D009467:Neuromuscular Depolarizing Agents; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; C013289:tetraphenylphosphonium