健康人冷应激前后直肠感觉和自主神经功能的变化

背景应激可以影响消化道内脏感觉功能,冷应激是一有效的应激刺激.目的研究冷应激前后直肠感觉阈值和自主神经张力的变化,探讨自主神经功能改变对直肠敏感性的影响.方法符合入选标准的健康志愿者15名,用电子恒压器测定直肠对气囊扩张的感觉阈值,同时分析心率变异性(HRV)以反映自主神经张力.数日后采用冷水浸手获得应激状态后重复上述实验.结果冷应激状态下,受试者初次感觉、初次排便感觉和便意窘迫感的容量阈值显著升高(P＜0.05);HRV频域分析显示低频带功率(P1)和低、高频带功率比(P1/P2)显著升高(P＜0.05).结论冷应激时直肠对容量刺激的敏感性降低可能与交感神经兴奋性升高有关.

Effect of Cold Stress on the Rectal Perception and Autonomic Nerve Function in Healthy Subjects

Stress may affect the visceral sensation of the gut and cold stress is an effective stressor. Aims: To investigate the changes of the thresholds of rectal perception and autonomic nervous tone induced by cold stress, and to reveal the autonomic nervous modulation to rectal sensitivity. Methods: Fifteen healthy volunteers were enrolled in this study. The rectal perception thresholds to balloon distension were determined by electronic barostat; and heart rate variability (HRV) was analyzed to reflect the autonomic nervous tone simultaneously. The experiments were repeated in a cold stress situation induced by cold water immersion on another day soon after. Results: In cold stress state, the thresholds to volume of the volunteers at the time of early sensation, first sensation of defecation and urgency of defecation increased significantly (P<0.05); and HRV analysis showed elevation of low frequency power (P_2) and low frequency power-to-high frequency power ratio (P_1/P_2) (P<0.05). Conclusions: Cold stress can diminish the rectal sensitivity to volume stimulus, which may be attributed to the increased sympathetic activity.