aDepartment of Anesthesiology and Biomedical Engineering bBiomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA.
J Hypertens. 2014 Feb;32(2):374-82. doi: 10.1097/HJH.0000000000000045.
Dietary sodium influences intermediate physiological traits in healthy adults independent of changes in blood pressure. The purpose of this study was to test the hypothesis that dietary sodium affects cardiac autonomic modulation during mental stress.
In a prospective, randomized cross-over design separated by 1 month between diets, 70 normotensive healthy young adults (F/M: 44/26, aged 18-38 years) consumed a 5-day low (10 mmol/day), normal (150 mmol), and high (400 mmol) sodium diet followed by heart rate variability (HRV) recordings at rest and during 5-min computerized mental arithmetic. Women were studied in the low hormone phase of the menstrual cycle following each diet.
Diet did not affect resting blood pressure, but heart rate (HR) (mean ± SE) was 66 ± 1, 64 ± 1, and 63 ± 1 bpm in low, normal, and high sodium conditions, respectively (analysis of variance P = 0.02). For HRV, there was a main effect of sodium on resting SD of normalized RR intervals (SDNN), square root of the mean squared difference of successive normalized RR intervals (RMSSD), high frequency, low-frequency normalized units (LFnu), and high-frequency normalized units (HFnu) (P < 0.01 for all). The response to low sodium was most marked and consistent with sympathetic activation and reduced vagal activity, with increased LFnu and decreased SDNN, RMSSD, and HFnu compared to both normal and high sodium conditions (P ≤0.05 for all). Dietary sodium-by-mental stress interactions were significant for mean NN, RMSSD, high-frequency power, LFnu, and low frequency/high frequency ratio (P < 0.05 for all). The interactions signify that sodium restriction evoked an increase in resting sympathetic activity and reduced vagal activity to the extent that mental stress caused modest additional disruptions in autonomic balance. Conversely, normal and high sodium evoked a reduction in resting sympathetic activity and incremental increase in resting vagal activity, which were disrupted to a greater extent during mental stress compared to low sodium.
We conclude that autonomic control of HRV at rest and during mental stress is altered by dietary sodium in healthy normotensive young adult men and women.
饮食中的钠会影响健康成年人的中间生理特征，而与血压变化无关。本研究的目的是检验饮食中的钠是否会影响精神压力下的心脏自主调节的假设。
在一项前瞻性、随机交叉设计的研究中，70 名血压正常的健康年轻成年人（F/M：44/26，年龄 18-38 岁）在 1 个月的时间内分别食用 5 天低（10mmol/天）、正常（150mmol）和高（400mmol）钠饮食，然后在休息和 5 分钟计算机化心理算术期间进行心率变异性（HRV）记录。在每次饮食后，女性都在月经周期的低激素期进行研究。
饮食不影响静息血压，但心率（HR）（平均值±SE）分别为低钠、正常钠和高钠条件下的 66±1、64±1 和 63±1bpm（方差分析 P=0.02）。对于 HRV，钠对静息 RR 间期归一化标准差（SDNN）、连续 RR 间期均方根差的平方根（RMSSD）、高频、低频归一化单位（LFnu）和高频归一化单位（HFnu）的主要效应（P<0.01 所有）。低钠的反应最为明显且一致，与交感神经激活和迷走神经活动减少有关，与正常和高钠条件相比，LFnu 增加，SDNN、RMSSD 和 HFnu 减少（P<0.05 所有）。饮食钠与精神压力的相互作用对平均 NN、RMSSD、高频功率、LFnu 和低频/高频比具有显著性（P<0.05 所有）。这些相互作用表明，钠限制引起静息交感神经活性增加，迷走神经活性降低，以至于精神压力引起自主平衡的适度额外破坏。相反，正常和高钠引起静息交感神经活性降低，静息迷走神经活性增加，与低钠相比，精神压力下的这种增加被更大程度地破坏。
我们得出结论，饮食中的钠会改变健康的血压正常年轻成年男性和女性的静息和精神压力下的 HRV 自主控制。
