A novel muscarinic receptor antagonist AF-DX 116 differentially blocks slow inhibitory and slow excitatory postsynaptic potentials in the rabbit sympathetic ganglia.
Muscarinic, slow postsynaptic potentials (s-epsp and s-ipsp) in the rabbit superior cervical ganglia were shown to be differentially depressed by a novel cardioselective M2-type antagonist AF-DX 116: it antagonized the s-ipsp with IC50 value of 1.5 X 10(-7) M, which is 16-fold more potent in depressing the s-ipsp than the s-epsp. A hyperpolarizing component in the biphasic potential changes induced by a muscarinic agonist, methacholine, was selectively eliminated by this antagonist. AF-DX 116 was thus shown to be an useful tool for discriminating the M2-type muscarinic responses from those of M1-type in the nervous system.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D018723:Bethanechol; D001626:Bethanechol Compounds / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology*; D008297:Male; D016210:Methacholine Chloride; D008688:Methacholine Compounds / Q000494:pharmacology; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D001626:Bethanechol Compounds; D008688:Methacholine Compounds; D011976:Receptors, Muscarinic; D018723:Bethanechol; D016210:Methacholine Chloride; D010890:Pirenzepine; C048593:otenzepad