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六小时水浸前后对生理应激源的心血管和自主神经反应。

Cardiovascular and autonomic responses to physiological stressors before and after six hours of water immersion.

作者信息

Florian John P, Simmons Erin E, Chon Ki H, Faes Luca, Shykoff Barbara E

机构信息

Navy Experimental Diving Unit, Panama City, Florida;

出版信息

J Appl Physiol (1985). 2013 Nov 1;115(9):1275-89. doi: 10.1152/japplphysiol.00466.2013. Epub 2013 Aug 15.

Abstract

The physiological responses to water immersion (WI) are known; however, the responses to stress following WI are poorly characterized. Ten healthy men were exposed to three physiological stressors before and after a 6-h resting WI (32-33°C): 1) a 2-min cold pressor test, 2) a static handgrip test to fatigue at 40% of maximum strength followed by postexercise muscle ischemia in the exercising forearm, and 3) a 15-min 70° head-up-tilt (HUT) test. Heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), cardiac output (Q), limb blood flow (BF), stroke volume (SV), systemic and calf or forearm vascular resistance (SVR and CVR or FVR), baroreflex sensitivity (BRS), and HR variability (HRV) frequency-domain variables [low-frequency (LF), high-frequency (HF), and normalized (n)] were measured. Cold pressor test showed lower HR, SBP, SV, Q, calf BF, LFnHRV, and LF/HFHRV and higher CVR and HFnHRV after than before WI (P < 0.05). Handgrip test showed no effect of WI on maximum strength and endurance and lower HR, SBP, SV, Q, and calf BF and higher SVR and CVR after than before WI (P < 0.05). During postexercise muscle ischemia, HFnHRV increased from baseline after WI only, and LFnHRV was lower after than before WI (P < 0.05). HUT test showed lower SBP, DBP, SV, forearm BF, and BRS and higher HR, FVR, LF/HFHRV, and LFnHRV after than before WI (P < 0.05). The changes suggest differential activation/depression during cold pressor and handgrip (reduced sympathetic/elevated parasympathetic) and HUT (elevated sympathetic/reduced parasympathetic) following 6 h of WI.

摘要

对水浸(WI)的生理反应是已知的;然而,WI后对应激的反应特征尚不明确。10名健康男性在6小时静息WI(32 - 33°C)前后接受了三种生理应激源测试:1)2分钟冷加压试验;2)以最大力量的40%进行静态握力试验直至疲劳,随后对运动的前臂进行运动后肌肉缺血试验;3)15分钟70°头高位倾斜(HUT)试验。测量了心率(HR)、收缩压和舒张压(SBP和DBP)、心输出量(Q)、肢体血流量(BF)、每搏输出量(SV)、全身及小腿或前臂血管阻力(SVR和CVR或FVR)、压力反射敏感性(BRS)以及HR变异性(HRV)频域变量[低频(LF)、高频(HF)和标准化值(n)]。冷加压试验显示,WI后HR、SBP、SV、Q、小腿BF、LFnHRV和LF/HFHRV降低,CVR和HFnHRV升高(P < 0.05)。握力试验显示,WI对最大力量和耐力无影响,WI后HR、SBP、SV、Q和小腿BF降低,SVR和CVR升高(P < 0.05)。在运动后肌肉缺血期间,仅WI后HFnHRV从基线升高,LFnHRV在WI后低于WI前(P < 0.05)。HUT试验显示,WI后SBP、DBP、SV、前臂BF和BRS降低,HR、FVR、LF/HFHRV和LFnHRV升高(P < 0.05)。这些变化表明,在6小时WI后,冷加压和握力试验期间存在不同的激活/抑制(交感神经降低/副交感神经升高),而HUT试验期间则是交感神经升高/副交感神经降低。

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