第四脑室周围组织的GABA在家兔低氧循环反应中的作用

THE ACTIONS OF GABA AROUND THE AREA OF THE FOURTH VENTRICLE ON CIRCULATORY RESPONSE TO ACUTE HYPOXIA IN RABBITS

本工作探讨第四脑室周围区域的GABA系统在家兔低氧循环反应中的作用。动物麻醉制动，经人工呼吸机吸入含氧量为11％的低氧混合气（模拟海拔高度6500m）。对照组（n＝11）第四脑室注射生理盐水100μl；实验组（n＝8）第四脑室注射Picrotoxin10μg／100μl。结果显示：对照组的动物第四脑室注射后对MAP和HR均无明显影响；实验组的动物第四脑室注射后MAP明显升高，HR无显著变化。两组动物均于第四脑室注射10分钟时进行低氧（时间15分钟）。对照组的动物低氧期间MAP和HR均明显降低，终止低氧5—10分钟时恢复；实验组的动物低氧期间HR明显降低，而且与对照组比较HR下降更为明显（P＜0．01），MAP与低氧前比较无显著变化。本工作有力地证明了正常情况下GABA对血管运动中枢有紧张性抑制作用；低氧引起的MAP下降与延髓区域的GABA系统活动加强有密切关系。

This paper erports the effects of injection of purotoxin at the fourth ventricle on the circulatory response to acute hypoxia. The rabbits were anesthetized with urethan and chloralose,immobilized with gal-lamine triethiodide and ventilated artificially. The animals were divided into two groups: the control group with the injection of physiological saline (100μl) and the experiment group with the injection of picrotoxin (10μg/100μl) at the fourth ventricle. The results indicated that the heart rate (HR) and the mean arterial pressure (MAP) in the control group presented significant decrease during acute hypoxia,then reached to the control level at 5-10min after normoxia; HR in the experiment group presented remarkabaly decrease during acute hypoxia and recovered after normoxia. The decrease of HR in experiment group was more ob-vious than that in the control group during acute hypoxia. MAP in the experiment group did not presente significant change during acute hypoxia. These results guggest that the decrease of MAP during hypoxia be mediated through the depressant effect of GABA around the area of the fourth ventricle.