title: [Etomidate (ET) produced differential effects on afferent sensory transmission to motor neurons (MNs) in neonatal rat spinal cord slices].
abstract: OBJECTIVE
  To investigate the effects of anesthetic ET treatment on afferent sensory- motor transmission in neonatal rat spinal cord ex vivo and the underlying mechanisms.
  
  
  METHODS
  Spinal cord slices from neonatal rats (7 - 14 days postnatal) were treated with ET at different concentrations. The conventional recording techniques for intracellular electrophysiological parameters were employed for the analysis of the dorsal root (DR) electric stimulation elicited excitatory postsynaptic potential (DR-EPSP) in MNs.
  
  
  RESULTS
  ET concentration-dependently suppressed the action potential (AP) and the frequency of firing in MNs. As compared to un-treated control, at 0.3, 3.0 (clinical concentration 0.8- 20.0 μmol/L ) and 30.0 μmol/L, ET significantly (P< 0.05 or P< 0.01) suppressed AP amplitude (mV: 57.5±33.5, 33.8±34.9, 31.2±34.9 vs.74.3±9.4, respectively). At 0.3 μmol/L, the effect of ET was differential : it significantly ( P< 0.05 ) increased the area under curve (AUC) for DR-EPSP (67.1±43.0 vs. 38.9±26.7), amplitude of N-methyl-D-aspartate (NMDA) receptor-mediated DR-EPSP (4.6±4.3 vs. 2.4±3.6 ), and the AUC of non-NMDA receptor-mediated DR-EPSP (78.4±53.6 vs. 70.5±32.7), but also reduced (P< 0.01) the amplitude of DR-EPSP (1.0±0.6 vs. 2.0±0.8) and the AUC of DR-EPSP (18.0±13.4 vs. 35.1±13.4). At concentrations ≥ 3.0 μmol/L, ET effect was totally inhibitory in a concentration-and time-dependent manner: the amplitude of DR-EPSP (as compared to their controls) at 3.0 and 30.0 μmol/L were (0.4±0.6 vs. 2.0±0.8) and (0.1±0.4 vs. 2.0±0.8), respectively, both P< 0.01.
  
  
  CONCLUSIONS
  ET can suppress AP and its firing frequency in MNs concentration-dependently in neonatal rat spinal cord ex vivo. At certain concentration, its effect is differential for DR-EPSP and the glutamate receptors mediating the afferents sensory-MN transmission.
authors: Cell Electrophysiology Laboratory, Wannan Medical College, Anhui, China.
authors: Chao
authors: C
authors: Zheng
authors: Meng-ya
authors: MY
authors: Wang
mesh_terms: D000818:Animals; D005045:Etomidate / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D005045:Etomidate