Dvorak R V, Poehlman E T
Department of Medicine, University of Vermont, Burlington 05405, USA.
Exp Gerontol. 1998 Aug;33(5):507-16. doi: 10.1016/s0531-5565(98)00002-3.
The sympathetic nervous system participates in the regulation of carbohydrate, lipid, and energy metabolism, and has been implicated in the pathogenesis of hypertension and obesity. Increased sympathetic nervous system activity with age may alter disease risk and contribute to the development of certain chronic diseases. Thus, we examined possible determinants of sympathetic nervous system activity in older normotensive women from infusions of tritiated norepinephrine (NE) to estimate rates of norepinephrine appearance and clearance. A secondary aim was to examine the association between norepinephrine kinetics and mean supine arterial blood pressure. Twenty-two older women (65.7 +/- 5.7 years) were characterized for resting NE kinetics, body composition, body fat distribution, peak aerobic capacity, leisure time physical activity energy expenditure (LTA), dietary carbohydrates, and daily energy intake. Analysis of univariate correlations revealed that only the LTA was significantly correlated with plasma NE appearance (r = 0.54, p < 0.01). Stepwise regression analysis identified LTA as the only significant predictor of plasma NE appearance rate with a total R2 = 0.29. The waist-to-hip ratio was selected as the only significant predictor of mean arterial blood pressure with an R2 = 0.30. When forced into the model, plasma NE appearance explained only 1% of the unique variance in mean arterial blood pressure. In summary, we found that: (1) higher levels of physical activity are related to higher plasma NE appearance in older women; (2) greater central body fatness is an independent predictor of mean arterial blood pressure; and (3) plasma NE appearance rate is a minor contributor to variation in mean arterial blood pressure in older, normotensive women.
交感神经系统参与碳水化合物、脂质和能量代谢的调节，并与高血压和肥胖的发病机制有关。随着年龄增长，交感神经系统活动增加可能会改变疾病风险，并促进某些慢性疾病的发展。因此，我们通过输注氚标记去甲肾上腺素（NE）来估计去甲肾上腺素的生成率和清除率，以研究老年血压正常女性交感神经系统活动的可能决定因素。第二个目的是研究去甲肾上腺素动力学与平均仰卧位动脉血压之间的关联。对22名老年女性（65.7±5.7岁）进行了静息NE动力学、身体成分、体脂分布、最大有氧能力、休闲时间体力活动能量消耗（LTA）、膳食碳水化合物和每日能量摄入的特征分析。单变量相关性分析显示，只有LTA与血浆NE生成显著相关（r = 0.54，p < 0.01）。逐步回归分析确定LTA是血浆NE生成率的唯一显著预测因子，总R2 = 0.29。腰臀比被选为平均动脉血压的唯一显著预测因子，R2 = 0.30。当纳入模型时，血浆NE生成仅解释了平均动脉血压独特变异的1%。总之，我们发现：（1）老年女性中较高水平的身体活动与较高的血浆NE生成有关；（2）更大的中心性肥胖是平均动脉血压的独立预测因子；（3）在老年血压正常女性中，血浆NE生成率对平均动脉血压变异的贡献较小。
