Schwartz R S, Jaeger L F, Veith R C
J Gerontol. 1987 Sep;42(5):546-51. doi: 10.1093/geronj/42.5.546.
Several studies have documented an increase in sympathetic nervous system (SNS) activity, as reflected by either plasma norepinephrine (NE) concentration or NE appearance rate, with aging. Because similar increases have been noted in young obese persons, and because adiposity increases with age, we hypothesized that body composition might be an important determinant of heightened SNS activity. Baseline SNS activity, energy expenditure, and responses to a standard formula "meal" were compared in 11 young (31.1 +/- 5 years) (m +/- SD) and 9 old (64.9 +/- 6.3 years) persons. Both baseline NE concentration, p less than .05, and the NE appearance rate, p less than .05, were increased in the elderly group. The percentage of body fat, p = .004, and age, p less than .02, were correlated independently with NE appearance rate but not with NE concentration. Although plasma NE increased after the meal in both groups, NE appearance increased in the young group only. We conclude that NE appearance rate is a better reflection of SNS activity than NE concentration. We also found that the percentage of body fat and age are independent determinants of baseline SNS activity, which together account for 52% of the variability in SNS activity, as reflected by NE appearance rate.
多项研究记录了随着年龄增长，交感神经系统（SNS）活动增加，这可通过血浆去甲肾上腺素（NE）浓度或NE出现率反映出来。由于在年轻肥胖者中也观察到了类似的增加，且肥胖程度会随着年龄增长，我们推测身体组成可能是SNS活动增强的一个重要决定因素。对11名年轻（31.1±5岁）（均值±标准差）和9名老年（64.9±6.3岁）人群的基线SNS活动、能量消耗以及对标准配方“餐食”的反应进行了比较。老年组的基线NE浓度（p<0.05）和NE出现率（p<0.05）均有所增加。体脂百分比（p = 0.004）和年龄（p<0.02）与NE出现率独立相关，但与NE浓度无关。虽然两组在餐后血浆NE均升高，但仅年轻组的NE出现增加。我们得出结论，NE出现率比NE浓度更能反映SNS活动。我们还发现，体脂百分比和年龄是基线SNS活动的独立决定因素，它们共同解释了以NE出现率反映的SNS活动变异性的52%。
