title: Steroid anaesthetics: inhibition of depolarization-secretion coupling at the mouse motor nerve terminal.
abstract: The coupling between nerve terminal depolarization and quantal secretion of acetylcholine at the mouse neuromuscular junction was estimated by measuring the multiplication of the frequency of miniature end-plate potentials (m.e.p.p.s) produced by increasing the concentration of calcium in the medium from 0.1 to 1.0 mM in the presence of 15 mM potassium. Depolarization-secretion coupling was inhibited by the anaesthetic steroids progesterone, pregnanedione, and alphaxalone. The nonanaesthetic steroid delta 16-alphaxalone also inhibited depolarization-secretion coupling with the same potency as alphaxalone. This results indicates that inhibition of depolarization-secretion coupling in nerve terminals is unlikely to play a major role in the production of anaesthesia.
mesh_terms: D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D009045:Motor Endplate / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects*; D009411:Nerve Endings / Q000187:drug effects*; D013256:Steroids / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D000777:Anesthetics; D013256:Steroids; D002118:Calcium