L-谷氨酰胺、谷氨酰胺分解酶和谷氨酰胺合成酶对豚鼠CAP阈值的影响

本文用负直流电300μA(—DC300μA)刺激豚鼠耳蜗圆窗,耗尽耳蜗突触前毛细胞内递质,然后分别用L-谷氯酰胺、谷氨酰胺分解酶和谷氨酰胺合成酶灌流鼓阶。结果表明,谷氨酰胺灌流后,耳蜗神经的CAP阈值明显提高,并使电刺激耳蜗圆窗所导致的CAP阈值的升高加速恢复。用谷氨酰胺合成酶灌流耳蜗鼓阶后能提高CAP阈值50dB,而用谷氨酰胺分解酶灌流则对CAP阈值影响很小。该结果提示L-谷氨酰胺可能为豚鼠耳蜗兴奋性传入递质的候选者。     

EFFECTS OF L-GLUTAMINE, GLUTAMINASE AND GLUTAMINE SYNTHETASE ON CAP THRESHOLD OF COCHLEAR NERVE OF GUINEA PIG

Negative direct current (__DC 300 μA) stimulation was applied to the round window ofthe guinea pig cochlea to exhaust the pre-synaptic intracellular reserves of the transmitter inhair cells, and then the scala tympani was perfused respectively with L- glutamine, glutaminesynthetase and glutaminase. Experimental results showed that the negative DC electricalstimulation applied to the round window elevated the CAP threshold of the cochlear nervein the basal turn of the cochlea, which recovered over a period of approximately 17- 39 min.The perfusion of L- glutamine apparently elevated the CAP threshold. The recovery of theCAP threshold following electrical stimulation, however, was accelerated by the perfusion of10 mmol/L L- glutamine. The time for recovery only took about 5- 6 min. The perfusion ofenzyme glutamine synthetase elevated the CAP threshold by 50 dB, while glutaminase hadlittle effect. These results suggest that the effect of L- glutamine on the CAP threshold inthe cocblea of the guinea pig ap     

L-天门冬氨酸对短声引起的豚鼠耳蜗电位的影响

以内含L-天门冬氨酸的人工外淋巴液灌流豚鼠耳蜗。在灌流过程中,鼓阶内记录耳蜗微音器电位(CM)和神经动作电位(APN_1)。并用计算机常规处理CM和APN_1。当用10mM和15mM的L-天门冬氨酸灌流时,显著增加短声诱发反应,但5mM的L-天门冬氨酸并不影响短声引起的活动。L-天门各氨酸可能包含于耳蜗传入突触内,并参与耳蜗传人突触的传递。