Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas.
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas.
Am J Physiol Regul Integr Comp Physiol. 2021 Mar 1;320(3):R307-R316. doi: 10.1152/ajpregu.00297.2020. Epub 2021 Jan 13.
Excessive salt intake is considered a risk factor for the development of hypertension. Additionally, aberrant neurocirculatory responses to a cold stimulus are associated with an increased risk of hypertension. This study aimed to determine whether salt loading versus salt reduction would impact hemodynamic and sympathetic neural responses during the cold pressor test (CPT) in premenopausal women with a history of normal pregnancy. Nine healthy premenopausal women [42 ± 3 (SD) yr] were given a standardized isocaloric high-salt (HS; 250 mEq sodium/day) or low-salt (LS; 50 mEq sodium/day) diet for 1-wk each (∼2 mo apart with the order randomized), while water intake was ad libitum. Laboratory testing was performed following each HS and LS period in the mid-luteal phase of the menstrual cycle. Subjects were in the supine position and beat-by-beat blood pressure (BP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) were continuously measured during 1-min baseline followed by 2-min CPT, and 3-min recovery. BP and HR increased during the CPT (both < 0.001); the responses were similar between HS and LS. MSNA increased during the CPT, but the increment (Δ) was greater during HS than LS (29 ± 6 vs. 15 ± 4 bursts/min; < 0.001). The transduction of MSNA for vasoconstriction during the CPT was lower in HS ( < 0.05). Thus, salt loading augments sympathetic neural reactivity to the cold stimulus with similar pressor responses compared with salt reduction, which may be attributed to the blunted neurovascular transduction-a compensatory mechanism for hemodynamic homeostasis in premenopausal women with a history of normal pregnancy.
过量的盐摄入被认为是高血压发展的一个危险因素。此外，对冷刺激的异常神经循环反应与高血压的风险增加有关。本研究旨在确定在有正常妊娠史的绝经前妇女中，盐负荷与盐减少是否会影响冷加压试验（CPT）期间的血液动力学和交感神经神经反应。9 名健康的绝经前妇女[42±3（SD）岁]分别接受 1 周的标准等热量高盐（HS；250 mEq 钠/天）或低盐（LS；50 mEq 钠/天）饮食（约相隔 2 个月，顺序随机），同时自由饮水。在每个 HS 和 LS 期后，在月经周期的黄体中期进行实验室测试。受试者处于仰卧位，在 1 分钟基线后连续测量每搏血压（BP）、心率（HR）和肌肉交感神经活动（MSNA），接着进行 2 分钟 CPT 和 3 分钟恢复。CPT 期间 BP 和 HR 升高（均<0.001）；HS 和 LS 之间的反应相似。CPT 期间 MSNA 增加，但 HS 时的增量（Δ）大于 LS（29±6 与 15±4 爆发/分钟；<0.001）。CPT 期间，MSNA 对血管收缩的转导在 HS 时较低（<0.05）。因此，与盐减少相比，盐负荷会增强对冷刺激的交感神经反应，而血压反应相似，这可能归因于神经血管转导减弱——这是有正常妊娠史的绝经前妇女血液动力学稳态的一种代偿机制。
