Recurrent low frequency sensorineural deafness / 临床耳鼻咽喉头颈外科杂志

Low frequency sensorineural deafness is a common subtype of idiopathic sudden deafness. Certain patients suffered recurrent attacks without vertigo, much alike Meniere's disease. Few of them developed into definite Meniere's disease during long-term follow-up in many clinical studies. Although the pathophysiology of recurrent low frequency deafness is yet unknown, the desease is considered associated with early state of endolymphatic hydrops or migraine. Otologists shall be aware of its clinical course and careful explanation is necessary at time of initial informed consent.

Inhibition of gamma-aminobutyric acid receptor-gated chloride currents by noradrenaline in rat spiral ganglion neuron / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the pharmacological modulatory properties of noradrenaline in the rat spiral ganglion neuron.</p><p><b>METHODS</b>Nystatin perforated patch recording technique under voltage-clamp conditions was used to record the modulatory effect of noradrenaline on the current evoked by gamma-amino butyric acid (GABA) in the spiral ganglion neuron.</p><p><b>RESULTS</b>The reversal potential of the GABA response was about (- 0.78 +/- 0.05) mV (n = 8), which was almost identical to the theoretical Cl- equilibrium potential. At the holding potential of -50 mV, GABA evoked inward current (I(GABA)) over the concentration range of 0.3 to 1 micromol/L. The EC50 and Hill coefficient for GABA were (5.2 +/- 0.5) micromol/L and 1.03 (n = 26). The I(GABA) was suppressed by bicuculline, the selective GABA-A receptor antagonist, and the chloride currents evoked by GABA was inhibited by noradrenaline.</p><p><b>CONCLUSIONS</b>The result indicates that noradrenaline depressed GABA-A receptor-gated chloride currents, which may contribute to the modulatory effect of sympathetic system on auditory transmission.</p>

Technique of rat cochlea slicing and study of rat spiral ganglion neurons by infrared visual slice patch clamp method / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To establishing the cochlea slice technique and infrared visual slice patch clamp method in order to observe the electrophysiological characteristics of rat spiral ganglion neurons (SGN) METHODS: SD rats were divided into three groups according to postnatal days old (0-2 d, 3-6 d and 7-14 d). Making slice of SD rat cochlear quickly, using infrared differential interference contrast (IR-DIC) technique, together with slice patch clamp, the electrophysiological characteristics of rat spiral ganglion neurons were observed, and factors which affected the quality of cochlear slice and recording of patch clamp were analyzed.</p><p><b>RESULTS</b>The success rate of 3-6 days SD was the highest, and 2-4 pieces of slice could be made from each cochlea. Cochlea connecting with partial skull and integrity of cochlear hull were the key for making slice, and the angle of modiolus axis should be adjusted to be parallel to the knife and the preparing time should be shorter. The SGN cell of good condition could be easily found and the seal test became easier with the help of infrared visual slice patch clamp method. The rest membrane potential was (-45.6 +/- 5.3) mV (x +/- s, n=52) and the current of Na+ and K+ could be activated.</p><p><b>CONCLUSIONS</b>Cochlear slice technique can retain structural integrity, cell viability and their association in cochlea, which suggest that this technique provides carrier for electrophysiological study of rat spiral ganglion neurons, and patch clamp with infrared videomicroscopy method can be used to make direct real-time observation in electrophysiological experiments of SGN, which can provide important technique support and reference for deep study of electrophysiological characteristics of SGN and auditory neurotransmission in cochlea.</p>