Best Stuart A, Okada Yoshiyuki, Galbreath M Melyn, Jarvis Sara S, Bivens Tiffany B, Adams-Huet Beverley, Fu Qi
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA UT Southwestern Medical Center, Dallas, TX, USA.
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.
Exp Physiol. 2014 Jun;99(6):839-48. doi: 10.1113/expphysiol.2013.077248. Epub 2014 Jan 17.
We compared the effect of age- and sex-related differences in haemodynamics, blood volume (BV) and left ventricular (LV) size and mass on resting muscle sympathetic nerve activity (MSNA) in healthy, normotensive adults. Twenty young men (19-47 years old) and 20 young women (21-46 years old) as well as 15 older men (62-80 years old) and 15 older women (60-82 years old) were studied. Cardiac output (acetylene rebreathing), total peripheral resistance, forearm vascular resistance (FVR; venous occlusion plethysmography) and MSNA were measured during supine rest. Blood volume was calculated (CO rebreathing), and LV mass, end-diastolic (LVEDV) and end-systolic volumes (LVESV) were measured using magnetic resonance imaging. Cardiac index (P < 0.001 and P = 0.016), BV (both P < 0.001), LV mass (P < 0.001 and P = 0.002), LVEDV (P < 0.001 and P = 0.002) and LVESV (both P < 0.001) were lower in the older and female groups, respectively. Total peripheral resistance was significantly higher in the older (P < 0.001) and female groups (P = 0.014), but FVR was increased in the female groups (P = 0.048) only (age, P = 0.089). The MSNA was greater in the older groups (P < 0.001) only (sex, P = 0.228). Increased MSNA was shown to correlate with a decrease in BV (P = 0.004) in men only when adjusted for age (women, P = 0.133). There was a positive relation between MSNA and FVR (P = 0.020) in men but not women (P = 0.422). There were no significant relations between MSNA and LV mass, LVEDV or LVESV. The findings suggest that the increase in resting MSNA with age may be related to the decline in BV in men only, but it is unknown whether sex differences in sympathetic adrenergic vasoconstriction occur independently of these changes.
我们比较了健康、血压正常的成年人中，年龄和性别相关的血流动力学、血容量（BV）以及左心室（LV）大小和质量差异对静息肌肉交感神经活动（MSNA）的影响。研究对象包括20名年轻男性（19 - 47岁）、20名年轻女性（21 - 46岁）、15名老年男性（62 - 80岁）和15名老年女性（60 - 82岁）。在仰卧位静息状态下测量心输出量（乙炔重呼吸法）、总外周阻力、前臂血管阻力（FVR；静脉阻断体积描记法）和MSNA。计算血容量（心输出量重呼吸法），并使用磁共振成像测量左心室质量、舒张末期容积（LVEDV）和收缩末期容积（LVESV）。老年组和女性组的心脏指数（P < 0.001和P = 0.016）、BV（均P < 0.001）、左心室质量（P < 0.001和P = 0.002）、LVEDV（P < 0.001和P = 0.002）和LVESV（均P < 0.001）分别较低。老年组（P < 0.001）和女性组（P = 0.014）的总外周阻力显著较高，但仅女性组的FVR增加（P = 0.048）（年龄，P = 0.089）。仅老年组的MSNA较大（P < 0.001）（性别，P = 0.228）。仅在对年龄进行校正后，男性中MSNA增加与BV降低相关（P = 0.004）（女性，P = 0.133）。男性中MSNA与FVR呈正相关（P = 0.020），而女性中无此相关性（P = 0.422）。MSNA与左心室质量、LVEDV或LVESV之间无显著相关性。研究结果表明，静息MSNA随年龄增加可能仅与男性BV下降有关，但尚不清楚交感肾上腺素能血管收缩的性别差异是否独立于这些变化而发生。
