急性低压缺氧对狗胃肠移行复合运动的影响

Effect of acute hypobaric hypoxia on gastrointestinal migrating motor complex in dogs

目的 在低压舱中模拟不同高度状态 ,观察狗消化间期胃肠移行性复合运动 (MMC)和血浆胃动素的变化。 方法 应用低顺应性毛细管水灌注消化道腔内测压系统记录清醒狗胃和十二指肠的收缩活动。先在低压舱海平面记录狗正常 MMC,然后分别在 MMC 相初期和后期模拟升至 30 0 0 m和 5 0 0 0 m高度停留 1h,记录 MMC的变化 .并在不同时间点抽取静脉血测定血浆胃动素浓度。 结果 30 0 0 m高度对 MMC无明显影响 ,但在 5 0 0 0 m高度发现 :1狗 MMC周期时间延长 ,主要是 相时间延长 , 相时间缩短 ;2在 MMC 相初期模拟升空 ,胃窦和十二指肠 MMC 相收缩振幅和动力指数明显低于海平面对照 (P<0 .0 5 ,P<0 .0 1) ,MMC 相被抑制 ;3在 MMC 相后期模拟升至 5 0 0 0 m高度 ,MMC 相仍能出现 ,但其收缩振幅和动力指数明显降低 (P<0 .0 5 ,P<0 .0 1) ;4在海平面 ,血浆胃动素随 MMC周期出现周期性波动 ,其浓度在 MMC 相时最高 ,在MMC 相时最低。在 MMC 相后期升至 5 0 0 0 m高度 ,虽有血浆胃动素高峰 ,但胃动素高峰浓度明显低于海平面对照 (P<0 .0 5 ) ;而在 MMC 相初期升至 5 0 0 0 m 高度 ,则血浆胃动素浓度无明显高峰出现。 结论 急性暴露低压低氧干扰了胃肠 MMC的活动 ,血浆胃动素释放减少可能介导了胃肠抑制作用。

Objectives To explore the effect of hybobaric hypoxia at various altitudes on gastrointestinal migrating motor complex (MMC) and plasma motilin level in conscious dogs. Methods Gastrointestinal contractile activity was measured with low compliance capillary water perfusion manometric system. MMC at sea level was recorded as control, and MMCs during exposure to 3 000 m or 5 000 m altitude for one hour began in early or late phaseⅡof MMC were taken and compared with that of control. Blood samples in different phases of MMC were collected for measuring plasma motilin concentrations. Results As compared with those of control, no significant changes of MMC indexes were found during 3 000 m exposure. During 5 000 m exposure, it was found : as compared with control, ① period of MMC, especially phaseⅡ was prolonged, and phase Ⅲ was shortened (P<0.05, P<0.01); ②amplitude and motility index of contractions in phaseⅡdecreased significantly(P<0.05,P<0.01), and phase Ⅲ was suppressed when 5 000 m exposure began in early phaseⅡ. ③ when 5 000 m exposure began in late phaseⅡ, phaseⅢ appeared, however its amplitude and motility index were significantly lower than those of control(P<0.05, P<0.01). ④ at sea level, plasma motilin levels showed cyclical fluctuations in different phases of MMC, it was highest in phase Ⅲ and lowest in phaseⅠ. The peak plasma motilin level in phase Ⅲ during 5 000 m exposure began in late phaseⅡ was lower than that of control (P<0.05), and no obvious peak level of motilin was noted during 5 000 m exposure began in early phaseⅡ. Conclusions Acute hypobaric hypoxia exposure may lead disturbance of MMC, and the lowered motilin release may be involved in the inhibition of gastrointestinal contractile activity.