Cao Lei, Graham Stuart L, Pilowsky Paul M
The Heart Research Institute and The University of Sydney, New South Wales, Australia; and.
Australian School of Advanced Medicine, Macquarie University, New South Wales, Australia.
Am J Physiol Regul Integr Comp Physiol. 2016 Jul 1;311(1):R49-56. doi: 10.1152/ajpregu.00486.2015. Epub 2016 May 4.
The role of vagal function in cardiovascular risk in older women remains unclear. Autonomic modulation following carbohydrate ingestion (CI) and postural stress (PS) were investigated in 14 healthy men and 21 age-matched postmenopausal women (age: 65.0 ± 2.1 vs. 64.1 ± 1.6 years), with normal and comparable insulin sensitivity. Continuous noninvasive finger arterial pressure and ECG were recorded in the lying and the standing positions before and after ingestion of a carbohydrate-rich meal (600 kcal, carbohydrate 78%, protein 13%, and fat 8%). Low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.4 Hz) components (ms(2)) of heart rate variability (HRV), low-frequency power (mmHg(2)) of systolic blood pressure variability (SBP LF power), and the sequence method for spontaneous baroreflex sensitivity (BRS, ms/mmHg) were used to quantify autonomic modulation. In response to CI and PS, mean arterial pressure maintained stable, and heart rate increased in women and men in the lying and standing positions. Following CI (60, 90, and 120 min postprandially) in the standing position, SBP LF power increased by 40% in men (P = 0.02), with unchanged HRV parameters; in contrast, in women, HRV HF power halved (P = 0.02), with unaltered SBP LF power. During PS before and after CI, similar magnitude of SBP LF power, HRV, and BRS changes was observed in men and women. In conclusion, CI induces sex-specific vascular sympathetic activation in healthy older men, and cardiac vagal inhibition in healthy older women; this CI-mediated efferent vagal inhibition may suggest differential cardiovascular risk factors in women, irrespective of insulin resistance, and impairment of autonomic control.
迷走神经功能在老年女性心血管风险中的作用仍不清楚。对14名健康男性和21名年龄匹配的绝经后女性(年龄:65.0±2.1岁与64.1±1.6岁)进行了研究,这些女性胰岛素敏感性正常且相当,研究了碳水化合物摄入(CI)和体位应激(PS)后的自主神经调节。在摄入富含碳水化合物的餐食(600千卡,碳水化合物78%,蛋白质13%,脂肪8%)之前和之后,分别在卧位和立位记录连续无创手指动脉压和心电图。采用心率变异性(HRV)的低频(LF,0.04 - 0.15赫兹)和高频(HF,0.15 - 0.4赫兹)成分(毫秒²)、收缩压变异性的低频功率(毫米汞柱²)(SBP LF功率)以及自发性压力反射敏感性的序列法(BRS,毫秒/毫米汞柱)来量化自主神经调节。对CI和PS的反应中,男女在卧位和立位时平均动脉压保持稳定,心率增加。立位时CI后(餐后60、90和120分钟),男性SBP LF功率增加40%(P = 0.02),HRV参数未改变;相比之下,女性HRV HF功率减半(P = 0.02),SBP LF功率未改变。在CI前后的PS期间,男女观察到相似幅度的SBP LF功率、HRV和BRS变化。总之,CI在健康老年男性中诱导性别特异性的血管交感神经激活,在健康老年女性中诱导心脏迷走神经抑制;这种CI介导的传出迷走神经抑制可能提示女性存在不同的心血管危险因素,与胰岛素抵抗和自主神经控制受损无关。