Salt intake may alter blood pressure (BP) regulation, but no study has investigated the impact of salt reduction versus salt loading on morning blood pressure surge (MBPS) and sympathetic neural control in premenopausal women with a history of normal pregnancy. Nine healthy women [42±3 (SD) yr] were given a low-salt (LS; 50 mEq sodium/day) and high-salt diet (HS; 250 mEq sodium/day) for 1 week each (~2-month apart with the order randomized), while water intake was ad libitum. Twenty-four-hour ambulatory BP was measured and the percent change in blood volume (BV) was calculated following LS and HS. MBPS was defined as the morning systolic BP (averaged for 2-hour after wake-up) minus the lowest nocturnal systolic BP. Beat-by-beat BP, heart rate, and muscle sympathetic nerve activity (MSNA) were measured during supine rest. Signal-averaging was used to characterize changes in beat-by-beat mean arterial pressure and total vascular conductance following spontaneous MSNA bursts to assess sympathetic vascular transduction. Ambulatory BP and MBPS (32±7 vs. 26±12 mmHg, p=0.208) did not differ between LS and HS. From LS to HS, BV increased by 4.3±3.7% (p=0.008). MSNA (30±20 vs. 18±13 bursts·100 heart beats^-1, p=0.005) was higher whereas sympathetic vascular transduction was lower in LS than HS (both, p<0.01). Changes in MSNA from LS to HS were correlated to %changes in BV (r=-0.673, p=0.047). Thus, salt intake affects sympathetic neural control but not MBPS in premenopausal women with a history of normal pregnancy. The underlying mechanisms remain unknown, however, alterations in sympathetic vascular transduction may, in part, contribute.

中文翻译：

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有正常妊娠史的绝经前妇女的盐摄入量会影响交感神经控制，但不会影响早晨血压的升高。

食盐摄入可能会改变血压（BP）的调节水平，但没有研究调查过减盐与加盐量对有正常妊娠史的绝经前妇女早晨血压波动（MBPS）和交感神经控制的影响。九名健康女性（42±3（SD）岁）分别接受低盐饮食（LS； 50 mEq钠/天）和高盐饮食饮食（HS； 250 mEq钠/天），每星期（约2个月）除了随机顺序外），饮水量是任意的。测量24小时动态血压，并根据LS和HS计算血容量（BV）的百分比变化。MBPS定义为早晨收缩压（唤醒后平均2小时）减去最低的夜间收缩压。仰卧休息期间测量心律失常的血压，心律和肌肉交感神经活动（MSNA）。信号平均用于表征自发性MSNA爆发后逐搏平均动脉压和总血管导度的变化，以评估交感性血管转导。流动性BP和MBPS（32±7 vs. 26±12 mmHg，p = 0.208）在LS和HS之间没有差异。从LS到HS，BV增加了4.3±3.7％（p = 0.008）。MSNA（30±20 vs. 18±13爆发·100次心跳^-1，p = 0.005）较高，而LS中的交感性血管转导低于HS（两者，p <0.01）。从LS到HS的MSNA变化与BV的变化百分比相关（r = -0.673，p = 0.047）。因此，盐摄入量影响具有正常妊娠史的绝经前妇女的交感神经控制，但不影响MBPS。潜在的机制仍然未知，但是，交感性血管转导的改变可能部分地起作用。