缺氧及谷氨酸对大鼠下丘脑神经元NMDA通道的影响

目的　研究缺氧和N 甲基 D 天门冬氨酸 (N methyl D asparticacid ,NMDA)通道激动剂谷氨酸对大鼠下丘脑神经元NMDA通道开放动力学的影响。方法　运用膜片钳技术的细胞吸附式方法记录NMDA通道的单通道电流。结果　在急性缺氧条件下 ,NMDA通道的开放增大 ,开放时间常数τ1,τ2 分别由 (0 .3 3± 0 .10 )ms ,(4.3 6± 0 .2 6)ms变为 (0 .93± 0 .2 2 )ms ,(7.64± 0 .72 )ms ,关闭时间常数τ1,τ2 分别由 (18.0 3± 3 .5 0 )ms ,(171.5 0± 19.10 )ms变为 (3 .42± 1.0 2 )ms ,(19.3 9± 3 .0 7)ms。平均开放概率由 0 .12± 0 .0 5变为 0 .66± 0 .3 6。谷氨酸浓度增加 ,NMDA通道开放时间常数增大、关闭时间常数减小 ,开放概率增大。结论　缺氧及谷氨酸能提高下丘脑神经元NMDA通道的兴奋性 ,促进NMDA通道开放增加。

he roles of hypoxia and glutamic acid on NMDA receptor channel of hypothalamic neuron in rats

Objective　To study the effects of hypoxia and glutamic acid on the kinetic properties of NMDA receptor channel of the hypothalamic neurons in rats. Methods　Cell-attached mode patch clamp technique was employed to record the single channel current of the NMDA receptor. Results　The open probability of NMDA receptor channel was increased after acute hypoxia compared with that of normal state, the open time τ1,τ2 was changed from (0.33±0.10)ms，(4.36±0.26)ms to (0.93±0.22)ms，(7.64±0.72)ms, and the close time τ1,τ2 was from (18.03±3.50)ms，(171.50±19.10)ms to (3.42±1.02)ms，(19.39±3.07)ms. The mean open probability was changed from 0.12±0.05 in normal state to 0.66±0.36 in hypoxia state. Furthermore, glutamic acid can increase open time and open probability of NMDA receptor channel,decrease close time. Conclusion　The excitability and the open probability of NMDA receptor channel of hypothalamic neurons increased by hypoxia is related to glutamate.