Muscarinic agonists block five different potassium conductances in guinea-pig sympathetic neurones.
Muscarinic excitation of sympathetic ganglion cells has usually been thought to result from inhibition of an outward K+ current, the M current, although in other neurones several conductances have been shown to be blocked by muscarinic agonists. We report that, as well as resting K+ conductance, all of four different K+ conductances, two voltage-dependent (M currents and A currents) and two calcium-dependent (responsible for slow and very slow afterhyperpolarizations), present in different sub-types of guinea-pig sympathetic neurones, are inhibited by the muscarinic agonists, bethanechol and muscarine. All of these effects increase neurone excitability and can lead to repetitive discharge.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D018723:Bethanechol; D001626:Bethanechol Compounds / Q000494:pharmacology*; D005728:Ganglia, Sympathetic / Q000187:drug effects; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009116:Muscarine / Q000494:pharmacology*; D009431:Neural Conduction / Q000187:drug effects*; D011188:Potassium / Q000502:physiology*
D001626:Bethanechol Compounds; D018723:Bethanechol; D009116:Muscarine; D011188:Potassium