尾部悬吊对大鼠肺循环血液动力学的动态影响

Dynamic Effects of Tail-suspension on Hemodynamics of Pulmonary Circulation in Rats

目的研究尾部悬吊模拟失重对大鼠肺循环的影响,为模拟失重对肺循环局部调节与立位耐力和运动能力降低机制研究积累资料。方法 -30°尾部悬吊(tail-suspension,TS)模拟失重的生理效应,Wistar雄性大鼠被随机分成3组:对照组(Con)、7d尾部悬吊组(TS7)和14d尾部悬吊组(TS14)。采用PowerLab/4SP生理记录系统记录肺动脉压、肺静脉压;超声流量计检测肺动脉流量。结果 TS7、TS14组大鼠肺动脉收缩压(arterial systolic blood pressure,SBP)显著降低(P<0.05),TS7组肺动脉舒张压(arterial diastolic blood pressure,DBP)有降低趋势,TS14组大鼠肺动脉DBP显著降低。TS7、TS14组大鼠肺动脉平均压(mean arterial pressure,MAP)均显著(P<0.05)或极显著降低(P<0.01)。TS7、TS14组大鼠静脉压变化不明显。TS7、TS14组大鼠平均动、静脉压压差显著减小主要为动脉端压力变化所致。TS14组大鼠心率(heart rate,HR)是血容量减少的代偿反应,TS7组每分肺动脉流量有增加趋势,可能为从初期反应期到基本适应期肺循环的超调现象所致。结论 TS7和TS14肺动脉端阻力和肺循环阻力显著减小主要起因于肺动脉端压力变化,可能是造成模拟失重后立位耐力和运动能力降低的原因。

Objective To study dynamic effects of simulated weightlessness with tail-suspension（TS） on the hemodynamics of pulmonary circulation in rats, so that to gather data for researches on mechanism of local regulation of pulmonary circulation and mechanism of orthostatic intolerance and the decrease of exercise capability. Methods -30° tail-suspended rats were used as the model to simulate the physiological effects of weightlessness. Wistar rats were randomly arranged into：control group （Con）, 7 d TS group （ TS7） and 14 d TS group（TS14）. The effects of TS on the pressure of pulmonary arteries, veins and ECG were recorded with a PowerLab/4SP physiological system, and the pulmonary arterial volume was measured with Transonic Systems. Results The systolic blood pressure in the pulmonary arteries decreased significantly in the TS7 and TS14 rats（P0.05）, and the diastolic blood pressure tended to decrease in the pulmonary arteries. The mean blood pressure in the pulmonary arteries decreased significantly（P0.05） or very significantly（P0.01） in the TS7 and TS14 rats. There was no significant change and difference among three groups in the pulmonary venous pressure. The significant decrease of the differences between the mean blood pressure in the pulmonary arteries and mean pulmonary venous pressure were due to the changes of pulmonary arterial system. The heart rate （HR） increase was the compensatory response of blood volume reduction. The slight increase of pulmonary arterial volume per minute in the TS7 rats could be due to the super-regulatory phenomena from the initial react stage to the basic adaptive stage. Conclusion The significant decrease ofresistance in the pulmonary arteries and pulmonary circulation is mainly caused by the changes of pulmonary arterial pressure and may be the cause of the orthostatic intolerance and the decrease of exercise capability after simulated weightlessness.