Charkoudian N, Eisenach J H, Joyner M J, Roberts S K, Wick D E
Dept. of Physiology and Biomedical Engineering, JO 4-184W, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
Am J Physiol Heart Circ Physiol. 2005 Dec;289(6):H2456-60. doi: 10.1152/ajpheart.00601.2005. Epub 2005 Sep 30.
Plasma osmolality alters control of sympathetic activity and heart rate in animal models; however, it is unknown whether physiological increases in plasma osmolality have such influences in humans and what effect concurrent changes in central venous and/or arterial pressures may have. We tested whether physiological increases in plasma osmolality (similar to those during exercise dehydration) alter control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) in humans. We studied 17 healthy young adults (7 women, 10 men) at baseline and during arterial pressure (AP) transients induced by sequential injections of nitroprusside and phenylephrine, under three conditions: control (C), after 1 ml/kg intravenous hypertonic saline (HT1), and after 2 ml/kg hypertonic saline (HT2). We continuously measured HR, AP, central venous pressure (CVP; peripherally inserted central catheter) and MSNA (peroneal microneurography) in all conditions. Plasma osmolality increased from 287 +/- 1 mosmol/kg in C to 290 +/- 1 mosmol/kg in HT1 (P < 0.05) but did not increase further in HT2 (291 +/- 1 mosmol/kg; P > 0.05 vs. C). Mean AP and CVP were similar between C and HT1, but both increased slightly in HT2. HR increased slightly but significantly during both HT1 and HT2 vs. C (P < 0.05). Sensitivity of baroreflex control of MSNA was significantly increased vs. C in HT1 [-7.59 +/- 0.97 (HT1) vs. -5.85 +/- 0.63 (C) arbitrary units (au).beat(-1).mmHg(-1); P < 0.01] but was not different in HT2 (-6.55 +/- 0.94 au.beat(-1).mmHg(-1)). We conclude that physiological changes in plasma osmolality significantly alter control of MSNA and HR in humans, and that this influence can be modified by CVP and AP.
在动物模型中，血浆渗透压会改变交感神经活动和心率的控制；然而，尚不清楚血浆渗透压的生理性升高在人类中是否有此类影响，以及中心静脉压和/或动脉压的同时变化可能会产生什么影响。我们测试了血浆渗透压的生理性升高（类似于运动性脱水期间的情况）是否会改变人类肌肉交感神经活动（MSNA）和心率（HR）的控制。我们研究了17名健康的年轻成年人（7名女性，10名男性），在三种情况下，分别于基线时以及在依次注射硝普钠和去氧肾上腺素诱导的动脉压（AP）瞬变期间进行研究：对照（C）、静脉注射1 ml/kg高渗盐水（HT1）后以及静脉注射2 ml/kg高渗盐水（HT2）后。我们在所有情况下持续测量心率、动脉压、中心静脉压（CVP；经外周静脉穿刺中心静脉导管测量）和肌肉交感神经活动（通过腓总神经微神经图测量）。血浆渗透压从对照时的287±1 mOsmol/kg升高至HT1时的290±1 mOsmol/kg（P<0.05），但在HT2时未进一步升高（291±1 mOsmol/kg；与对照相比，P>0.05）。对照和HT1时的平均动脉压和中心静脉压相似，但在HT2时两者均略有升高。与对照相比，HT1和HT2期间心率均略有但显著升高（P<0.05）。与对照相比，HT1时压力反射对肌肉交感神经活动的控制敏感性显著增加[-7.59±0.97（HT1）对-5.85±0.63（对照）任意单位（au）·次心跳-1·mmHg-1；P<0.01]，但在HT2时无差异（-6.55±0.94 au·次心跳-1·mmHg-1）。我们得出结论，血浆渗透压的生理变化会显著改变人类对肌肉交感神经活动和心率的控制，并且这种影响会受到中心静脉压和动脉压的调节。
