title: Action of enflurane on cholinergic transmission in identified Aplysia neurones.
abstract: Effects of enflurane on the cholinergic transmission in Aplysia neurones were studied by current and voltage clamp methods. Acetylcholine (ACh) evoked three types of postsynaptic responses on different identified neurones: (1) a depolarizing response due to an increase in Na and K conductances (D-response), (2) a fast hyperpolarizing response due to an increase in C1 conductance (C1-response), and (3) a slow hyperpolarizing response due to an increase in K conductance (K-response). Enflurane altered neither the action potential nor the membrane resistance of the neurones but depressed the three ACh-induced responses, non-competitively, in a dose-dependent manner. The K-response was less suppressed than the other two. Blockade of the closed state of ion channel was suggested by a reduction in the first ACh response evoked 1 min after administration of enflurane. The anaesthetic facilitated the decay of the neurally evoked e.p.s.c. and i.p.s.c. in suggesting a reduction in the mean open time of the postsynaptic ion channel. It is concluded that enflurane depresses excitatory and inhibitory cholinergic transmission by reducing the postsynaptic currents.
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001048:Aplysia; D004558:Electric Stimulation; D004737:Enflurane / Q000494:pharmacology*; D005724:Ganglia / Q000187:drug effects; D066298:In Vitro Techniques; D007478:Iontophoresis; D008564:Membrane Potentials / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D004737:Enflurane; D000109:Acetylcholine