Lindenberger Marcus, Länne Toste
Division of Physiology, Department of Medicine and Care, University Hospital, Linköping University, SE 58185 Linköping, Sweden.
Am J Physiol Heart Circ Physiol. 2007 Dec;293(6):H3568-74. doi: 10.1152/ajpheart.00725.2007. Epub 2007 Sep 28.
There are sex-related differences in venous compliance and capillary filtration in the lower limbs, which to some extent can explain the susceptibility to orthostatic intolerance in young women. With age, venous compliance and capacitance are reduced in men. This study was designed to evaluate age-related changes in venous compliance and capillary filtration in the lower limbs of healthy women. Included in this study were 22 young and 12 elderly women (23.1 +/- 0.4 and 66.4 +/- 1.4 yr). Lower body negative pressure (LBNP) of 11, 22, and 44 mmHg created defined transmural pressure gradients in the lower limbs. A plethysmographic technique was used on the calf to assess venous capacitance and net capillary filtration. Venous compliance was calculated with the aid of a quadratic regression equation. No age-related differences in venous compliance and capacitance were found. Net capillary filtration and capillary filtration coefficient (CFC) were lower in elderly women at a LBNP of 11 and 22 mmHg (0.0032 vs. 0.0044 and 0.0030 vs. 0.0041 ml.100 ml(-1).min(-1).mmHg(-1), P < 0.001). At higher transmural pressure (LBNP, 44 mmHg), CFC increased by approximately 1/3 (0.010 ml.100 ml(-1).min(-1).mmHg(-1)) in the elderly (P < 0.001) but remained unchanged in the young women. In conclusion, no age-related decrease in venous compliance and capacitance was seen in women. However, a decreased CFC was found with age, implying reduced capillary function. Increasing transmural pressure increased CFC in the elderly women, indicating an increased capillary susceptibility to transmural pressure load in dependent regions. These findings differ from earlier studies on age-related effects in men, indicating sex-specific vascular aging both in the venous section and microcirculation.
下肢静脉顺应性和毛细血管滤过存在性别差异，这在一定程度上可以解释年轻女性易患体位性不耐受的原因。随着年龄增长，男性的静脉顺应性和容量会降低。本研究旨在评估健康女性下肢静脉顺应性和毛细血管滤过的年龄相关变化。本研究纳入了22名年轻女性和12名老年女性（年龄分别为23.1±0.4岁和66.4±1.4岁）。通过11、22和44 mmHg的下体负压（LBNP）在下肢产生确定的跨壁压力梯度。采用体积描记技术测量小腿的静脉容量和净毛细血管滤过。借助二次回归方程计算静脉顺应性。未发现静脉顺应性和容量存在年龄相关差异。在11和22 mmHg的LBNP时，老年女性的净毛细血管滤过和毛细血管滤过系数（CFC）较低（分别为0.0032 vs. 0.0044和0.0030 vs. 0.0041 ml·100 ml⁻¹·min⁻¹·mmHg⁻¹，P < 0.001）。在较高的跨壁压力（LBNP为44 mmHg）下，老年女性的CFC增加了约1/3（0.010 ml·100 ml⁻¹·min⁻¹·mmHg⁻¹）（P < 0.001），而年轻女性则保持不变。总之，女性未出现静脉顺应性和容量随年龄下降的情况。然而，发现CFC随年龄降低，这意味着毛细血管功能下降。增加跨壁压力会使老年女性的CFC增加，表明依赖区域的毛细血管对跨壁压力负荷的敏感性增加。这些发现与早期关于男性年龄相关影响的研究不同，表明静脉段和微循环中存在性别特异性的血管老化。
