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Abstract：
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 yr; mean ± SD) were given a low-salt diet (LS; 50 mEq sodium/day) and high-salt diet (HS; 250 mEq sodium/day) for 1 wk each (~2 mo apart with the order randomized), while water intake was ad libitum. Ambulatory BP at 24 h 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 h 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 heartbeats, 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 percent 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.NEW & NOTEWORTHY This is the first study to demonstrate that MBPS and ambulatory BP were not affected by salt intake despite a significant change in sympathetic outflow in healthy premenopausal women with a history of normal pregnancy. This may be due to compensatory adaptations in MSNA and sympathetic vascular transduction during salt reduction versus salt loading.
摘要：
盐的摄入可能会改变血压（BP）的调节，但没有研究调查盐减量与盐负荷对有正常妊娠史的绝经前妇女晨间血压升高(MBPS)和交感神经控制的影响.9名健康女性（42±3岁；平均值±SD）接受低盐饮食（LS;50mEq钠/天）和高盐饮食（HS;250mEq钠/天），每周1周（间隔约2个月，随机顺序），而水的摄入量是随意的。测量24小时动态血压，并在LS和HS后计算血容量（BV）的百分比变化。MBPS定义为早晨收缩压BP（唤醒后2小时的平均值）减去最低的夜间收缩压BP。挨打的BP,心率,在仰卧休息期间测量肌肉交感神经活动（MSNA）。信号平均用于表征自发性MSNA爆发后逐次平均动脉压和总血管电导的变化，以评估交感神经血管转导。动态血压和MBPS（32±7vs.26±12mmHg,P=0.208）在LS和HS之间没有差异。从LS到HS,BV增加4.3±3.7%(P=0.008)。MSNA(30±20vs.18±13次爆发/100次心跳，P=0.005)更高，而LS中的交感神经血管转导低于HS(两者，P<0.01)。MSNA从LS到HS的变化与BV的变化百分比相关（r=-0.673；P=0.047）。因此，盐摄入影响交感神经控制，但不影响有正常妊娠史的绝经前妇女的MBPS。潜在的机制仍然未知；然而，交感神经血管转导的改变，在某种程度上,contribute.NEW＆NOTEWORTHY这是第一项研究，表明尽管有正常妊娠史的健康绝经前妇女的交感神经流出显着变化，但MBPS和动态BP不受盐摄入的影响。这可能是由于盐减少相对于盐负荷期间MSNA和交感神经血管转导的代偿适应。
