Jablonski Kristen L, Seals Douglas R, Eskurza Iratxe, Monahan Kevin D, Donato Anthony J
Dept. of Integrative Physiology, Univ. of Colorado, Boulder, CO 80309, USA.
J Appl Physiol (1985). 2007 Nov;103(5):1715-21. doi: 10.1152/japplphysiol.00533.2007.
Resting whole leg blood flow and vascular conductance decrease linearly with advancing age in healthy adult men. The potential role of age-related increases in oxidative stress in these changes is unknown. Resting leg blood flow during saline and ascorbic acid infusion was studied in 10 young (25 +/- 1 yr) and 11 older (63 +/- 2 yr) healthy normotensive men. Plasma oxidized LDL, a marker of oxidative stress, was greater in the older men (P < 0.05). Absolute resting femoral artery blood flow at baseline (iv saline control infusion) was 25% lower in the older men (238 +/- 25 vs. 316 +/- 38 ml/min; P < 0.05), and it was inversely related to plasma oxidized LDL (r = -0.56, P < 0.01) in all subjects. Infusion of supraphysiological concentrations of ascorbic acid increased femoral artery blood flow by 37% in the older men (to 327 +/- 52 ml/min; P < 0.05), but not in the young men (352 +/- 41 ml/min; P = 0.28), thus abolishing group differences (P = 0.72). Mean arterial blood pressure was greater in the older men at baseline (86 +/- 4 vs. 78 +/- 2 mmHg; P < 0.05), but it was unaffected by ascorbic acid infusion (P >/= 0.70). As a result, the lower baseline femoral artery blood flow in the older men was mediated solely by a 32% lower femoral artery vascular conductance (P < 0.05). Baseline femoral vascular conductance also was inversely related to plasma oxidized LDL (r = -0.65, P < 0.01). Ascorbic acid increased femoral vascular conductance by 36% in the older men (P < 0.05) but not in the young men (P = 0.31). In conclusion, ascorbic acid infused at concentrations known to scavenge reactive oxygen species restores resting femoral artery blood flow in healthy older adult men by increasing vascular conductance. These results support the hypothesis that oxidative stress plays a major role in the reduced resting whole leg blood flow and increased leg vasoconstriction observed with aging in men.
在健康成年男性中，静息状态下全腿血流量和血管传导率随年龄增长呈线性下降。氧化应激随年龄增长增加在这些变化中所起的潜在作用尚不清楚。我们对10名年轻（25±1岁）和11名年长（63±2岁）的健康血压正常男性进行了研究，观察生理盐水和抗坏血酸输注期间的静息腿部血流量。氧化应激的标志物——血浆氧化型低密度脂蛋白在年长男性中更高（P<0.05）。在基线时（静脉输注生理盐水对照），年长男性的静息股动脉血流量绝对值低25%（238±25 vs. 316±38 ml/min；P<0.05），并且在所有受试者中它与血浆氧化型低密度脂蛋白呈负相关（r=-0.56，P<0.01）。输注超生理浓度的抗坏血酸使年长男性的股动脉血流量增加37%（至327±52 ml/min；P<0.05），但在年轻男性中未增加（352±41 ml/min；P=0.28），从而消除了组间差异（P=0.72）。年长男性在基线时平均动脉血压更高（86±4 vs. 78±2 mmHg；P<0.05），但抗坏血酸输注对其无影响（P≥0.70）。因此，年长男性较低的基线股动脉血流量完全是由股动脉血管传导率低32%介导的（P<0.05）。基线股血管传导率也与血浆氧化型低密度脂蛋白呈负相关（r=-0.65，P<0.01）。抗坏血酸使年长男性的股血管传导率增加36%（P<0.05），但在年轻男性中未增加（P=0.31）。总之，输注已知能清除活性氧的浓度的抗坏血酸可通过增加血管传导率恢复健康老年男性的静息股动脉血流量。这些结果支持以下假设：氧化应激在男性衰老过程中观察到的静息全腿血流量减少和腿部血管收缩增加中起主要作用。
