This study tested the hypothesis that older hypertensive women display augmented pressor responses and aberrant sympathetic neural discharge patterning in response to orthostatic stress versus older hypertensive men. We evaluated, in older hypertensive and normotensive men and women (n=12 each group), blood pressure, heart rate, cardiac index (acetylene rebreathing), total peripheral resistance, and muscle sympathetic nerve activity (microneurography) at baseline (supine; 3 minutes) and during graded head-up tilt (30° for 5 minutes and 60° for 20 minutes). Sympathetic action potential discharge patterns were studied using wavelet-based methodology. In the upright posture, systolic and diastolic blood pressure responses were greater in hypertensive women versus hypertensive men and normotensive women (P<0.05). No differences existed in the heart rate, stroke index, or cardiac index response between groups; however, the total peripheral resistance response throughout graded head-up tilt was markedly greater in hypertensive women (P<0.01). Yet, the increase in integrated muscle sympathetic nerve activity burst frequency and burst incidence were similar between hypertensive women and men in the supine and upright postures. However, the increase in the mean action potential content per integrated burst and recruitment of previously dormant, larger-sized action potentials during 60° head-up tilt was greater in hypertensive women versus hypertensive men and normotensive women (P<0.001). Therefore, total sympathetic action potential firing frequency was markedly greater in hypertensive women throughout 60° head-up tilt (P<0.001). In conclusion, older hypertensive women displayed exaggerated pressor and peripheral vasoconstrictor responses to orthostasis versus hypertensive men, under conditions of augmented and aberrant sympathetic neural recruitment, rather than increased burst frequency, in the upright posture.

中文翻译：

---

老年高血压患者对平视倾斜的交感神经募集和血流动力学反应的性别差异

这项研究检验了这样一个假设，即老年高血压女性与老年高血压男性相比，在直立压力下表现出增强的升压反应和异常的交感神经放电模式。我们评估了老年高血压和正常血压男性和女性（每组 n=12）的血压、心率、心脏指数（乙炔再呼吸）、总外周阻力和肌肉交感神经活动（显微神经造影）（仰卧位；3分钟）和分级平视倾斜（30° 5 分钟和 60° 20 分钟）。使用基于小波的方法研究交感神经动作电位放电模式。在直立姿势下，与高血压男性和正常血压女性相比，高血压女性的收缩压和舒张压反应更大（P<0.05）。组间心率、中风指数或心脏指数反应不存在差异；然而，在高血压女性中，整个分级抬头倾斜的总外周阻力反应明显更大（P<0.01）。然而，在仰卧和直立姿势的高血压女性和男性之间，综合肌肉交感神经活动爆发频率和爆发发生率的增加相似。然而，与高血压男性和正常血压女性相比，高血压女性在 60° 抬头倾斜期间，每次综合爆发的平均动作电位含量的增加和先前休眠的、较大尺寸的动作电位的募集更大（P<0.001）。因此，在整个 60° 抬头倾斜期间，高血压女性的总交感神经动作电位激发频率显着更高（P<0.001）。综上所述，