卧床前后压力感受性反射机能变化的研究

许多数据表明长期失重以后立位耐力降低可能与压力感受性反射功能的改变有关。本文比较了两组被试者15天低动力卧床前后的立位耐力。以血压调节模型为基础分析了两种不同方式卧床前后单纯立位和下身负压加立位时压力感受性反射功能的改变,并用颈部加压及下身负压对中枢调节功能改变进行了观察。结果表明严格的头低位卧床后,立位耐力下降及压力感受性反射功能改变明显大于半日平卧半日倚坐者。而压力感受性反射功能的改变,特别是中枢神经系统调节功能的紊乱,是卧床后立位耐力降低的主要原因。从这种考虑为基础,作者提出了改变失重或模拟失重状态下的血液分布,调整对压力感受器的刺激,可能是预防心血管失调的有效方法。

THE STUDY OF BARORECEPTOR REFLEX FUNCTION BEFORE AND AFTER BED REST

Current data showed that lowering of orthostatic tolerance after prolonged weightlessness is most likely due to change of baroreceptor reflex function. In the present experiment orthostatic tolerance of two groups of subjects before .and after bed rest were studied, A previously established model of blood pressure regulation during orthostation was used to analyze the change of baroreceptor reflex function during the head-up tilt (HUT) and the head-up tilt plus lower body nagative pressure ( HUT + LBNP ) before and after bed rest. The changes of CNS regulatory function were also observed during neck pressurization and LBNP.Results showed that the changes of orthostatic tolerance and baroreceptor reflex function after strictly supine bed rest was more marked than that after bed rest of 13 hours supine and 11 hours reclining. The changes of baroreceptor reflex,especially the disturbance of CNS regulation function are the main factors causing the decrease of orthostatic tolerance after bed rest. It is suggested that reducing the cephalic fluid shift and adjusting the stimulation of baroreceptor may be effective in preventing the disturbance of cadiovascular function during weightlessness and/or simulated weightlessness.