Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States.
Department of Exercise Science and Physical Education, Montclair State University, Montclair, New Jersey, United States.
J Appl Physiol (1985). 2024 Aug 1;137(2):374-381. doi: 10.1152/japplphysiol.00833.2023. Epub 2024 Jul 4.
The sympathetic nervous system is critical for regulating blood pressure (BP) via the arterial baroreflex and sympathetic transduction in the peripheral vasculature. These mechanisms interact, and both may be altered with aging and impacted by menopause. Although age-related decreases in sympathetic transduction have been demonstrated in women, it remains unclear whether sympathetic baroreflex sensitivity (BRS) is impaired in postmenopausal women (POST). We tested the hypothesis that sympathetic BRS would be enhanced in POST compared with premenopausal women (PRE). We examined beat-by-beat BP and muscle sympathetic nerve activity (MSNA) in 19 PRE (22 ± 2 yr, 22 ± 3 kg/m) and 12 POST (57 ± 5 yr, 24 ± 2 kg/m) during 10 min of rest. Spontaneous sympathetic BRS was quantified as the slope of a linear regression between MSNA burst incidence and diastolic BP. Sympathetic transduction to mean arterial pressure (MAP) for the 10 cardiac cycles following spontaneous MSNA bursts was assessed via signal averaging method. Resting MAP was similar (PRE: 82 ± 8 vs. POST: 85 ± 8 mmHg, = 0.43), whereas resting MSNA was elevated in POST (PRE: 10 ± 6 vs. POST: 45 ± 16 bursts/100 heart beats, < 0.0001). Spontaneous sympathetic BRS was enhanced in POST (PRE: -2.0 ± 1.2 vs. POST: -5.2 ± 1.9 bursts/beat/mmHg, < 0.0005). Sympathetic transduction to MAP was attenuated in POST (time: < 0.001, group: < 0.001, interaction: < 0.01). These data suggest that sympathetic BRS may be enhanced in POST. Consistent with recent hypotheses, enhanced sensitivity of the arterial baroreflex's neural arc may signify a compensatory response to reduced efficiency of the peripheral arterial baroreflex arc (i.e., sympathetic transduction) to preserve BP buffering capacity. Studies examining sympathetic baroreflex function with aging remain equivocal, with some studies showing an increase, decrease, or no change in sympathetic baroreflex sensitivity (BRS) in older adults compared with younger adults. With aging, women experience unique physiological changes due to menopause that influence autonomic function. For the first time, we show that postmenopausal women exhibit a greater sympathetic BRS compared with young premenopausal women.
交感神经系统通过动脉压力反射和外周血管中的交感神经转导对血压 (BP) 的调节至关重要。这些机制相互作用，并且随着年龄的增长和绝经的影响，两者都可能发生改变。尽管已经证明女性的交感神经转导随着年龄的增长而降低，但尚不清楚绝经后女性的交感神经压力反射敏感性 (BRS) 是否受损 (POST)。我们假设 POST 中的交感 BRS 会比 PRE 中的增强。我们在 19 名 PRE（22 ± 2 岁，22 ± 3 kg/m）和 12 名 POST（57 ± 5 岁，24 ± 2 kg/m）中检查了 10 分钟的休息时的逐拍血压和肌肉交感神经活动 (MSNA)。通过线性回归斜率来量化 MSNA 爆发与舒张压之间的自发性交感 BRS。通过信号平均方法评估 10 个心脏周期后自发性 MSNA 爆发后的平均动脉压 (MAP) 的交感神经转导。休息时的 MAP 相似（PRE：82 ± 8 vs. POST：85 ± 8 mmHg，= 0.43），而 POST 中的休息时的 MSNA 升高（PRE：10 ± 6 vs. POST：45 ± 16 次/100 次心跳，< 0.0001）。POST 中的自发性交感 BRS 增强（PRE：-2.0 ± 1.2 vs. POST：-5.2 ± 1.9 次/拍/mmHg，< 0.0005）。MAP 的交感神经转导在 POST 中减弱（时间：<0.001，组：<0.001，相互作用：<0.01）。这些数据表明，POST 中的交感 BRS 可能增强。与最近的假设一致，动脉压力反射神经弧的敏感性增强可能表明对周围动脉压力反射弧（即交感神经转导）效率降低的代偿反应，以维持血压缓冲能力。随着年龄的增长，关于交感神经压力反射功能的研究仍然存在争议，一些研究表明，与年轻成年人相比，老年人的交感神经压力反射敏感性（BRS）增加、降低或没有变化。随着年龄的增长，女性由于绝经而经历独特的生理变化，这会影响自主功能。我们首次表明，绝经后女性与年轻的绝经前女性相比，表现出更大的交感 BRS。
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