Effect Of Acute Hypoxia On The Potassium Channels Current Of Cochlear Spiral Ganglion Neurons In SD Newborn Rats

Objective: To observe the effect of acute hypoxia on potassium channel currents of short-term isolated and cultured neonatal SD rat spiral ganglion neurons. Providing further theoretical basis, when the inner ear damaged by hypoxia, the change of information transfer function affect auditory neurons in the auditory disorders.Methods:(1) Cultured in vitro neonatal 1 ~ 3 d Sprague Dawley(SD) rats SGNs and identified by immunofluorescence.(2) Whole-cell patch clamp recording mode was observed in outwardcurrent and characteristics of SGNs when perfusing with hypoxic PSS.(3) applied to different potassium channel blocker TEA and 4-AP observe the effects of acute hypoxia on SGNs outward currents.(4) enzyme-linked immunosorbent assay(ELISA) in the detection of acute hypoxia associated with potassium channel changes in intracellular second messenger c AMP and c GMP levels.Results:(1) enzymatically isolated neurons survive in good condition. Identified by immunofluorescence for cochlear spiral ganglion neurons.(2) SGNs outward currents was voltage-gated outward rectifier current, mainly including TEA-sensitive BKCa channel currents and 4-AP-sensitive KV channel currents.(3) When the clamp voltage hold at-60 m V, acute hypoxia enhances SGNs outward current in voltage-dependent manner, major enhancement 0 ~ + 60 m V voltage range of activation of the current magnitude, within 5min, + 60 m V activated currents ranging from(971.23 ±50.25) p A to(2361 ± 207.4) p A(n = 9, P<0.01). then a downward trend, After 10 min,enhancement of current compared with base current has no significant difference(P> 0.05).(4) Background perfusion TEA( 1 mmol / L) or 4-AP(1 mmol / L), the enhancement of the outward currents induced by hypoxia on the SGNs by TEA reduced significantly, 4-AP has no significant effect on hypoxia-induced outward current enhanced in SGNs.(5) detect the levels of c AMP and c GMP at 5min, 15 min, 20 min after hypoxia in SGNs. Hypoxia 5 min group compared with the control group, c AMP concentrations were significantly increased. hypoxia 15 min group compared with the control group, c AMP concentration changes were not statistically significant; 20 min hypoxia group compared with the normal group, c AMP levels decreased, c GMP concentration with prolonged hypoxia time, the overall downward trend, but after some rebound in 20 min.Conclusion: acute hypoxia in SD rats SGNs may be activated by the activation of Large conductance Ca2+-activated K+ channel(BKCa), causing K + outward current, neuronal membrane potential hyperpolarization, cell excitability decreased, affecting SGNs conduction. The changes in intracellular second messenger c AMP and c GMP-related.