Nitric oxide and attenuated reflex cutaneous vasodilation in aged skin
Nitric oxide and attenuated reflex cutaneous vasodilation in aged skin
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DOI：
10.1152/ajpheart.00871.2002
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发表时间：
2003-05-01
影响因子：
4.8
通讯作者：
Minson, CT
中科院分区：
文献类型：
--
作者：
Holowatz, LA;Houghton, BL;Minson, CT
老年人体温调节性皮肤血管舒张功能减弱。本研究的目的是检验一氧化氮（NO）依赖性机制的减少有助于老年受试者的皮肤血管舒张反射减弱的假设。七个年轻人（23 +/- 2岁）和七个老年人（71 +/- 6岁）的男性与两个微透析纤维在前臂皮肤。一个位点作为对照（林格氏输注），第二个位点用10 mM N-G-硝基-L-精氨酸甲酯灌注以在整个方案中抑制NO合酶（NOS）。用灌水服使中心温度升高1.0 ℃。红细胞（RBC）流量测定激光多普勒血流仪在每个微透析纤维。皮肤血管传导性（CVC）计算为RBC流量/平均动脉压，值表示为最大血管舒张（输注28 mM硝普钠）的百分比。NOS抑制剂使年轻受试者的CVC从75 +/- 6%最大CVC（CVCmax）降至53 +/- 3% CVCmax，使老年受试者的CVC从64 +/- 5% CVCmax降至29 +/- 2% CVCmax，核心温度升高1.0 ℃。因此，在此温度水平下，皮肤主动血管舒张（AVD）的NO依赖性部分占年轻受试者血管舒张的23%，占老年受试者血管舒张的60%（P < 0.001）。总之，NO介导的途径在高核心温度下对老年受试者的总血管舒张反应贡献更大。这表明皮肤血管舒张随年龄增长而减弱可能是由于血管对介导AVD的未知神经递质的反应性降低或降低。
Thermoregulatory cutaneous vasodilation is diminished in the elderly. The goal of this study was to test the hypothesis that a reduction in nitric oxide (NO)-dependent mechanisms contributes to the attenuated reflex cutaneous vasodilation in older subjects. Seven young (23 +/- 2 yr) and seven older (71 +/- 6 yr) men were instrumented with two microdialysis fibers in the forearm skin. One site served as control ( Ringer infusion), and the second site was perfused with 10 mM N-G-nitro-L-arginine methyl ester to inhibit NO synthase ( NOS) throughout the protocol. Water-perfused suits were used to raise core temperature 1.0degreesC. Red blood cell (RBC) flux was measured with laser-Doppler flowmetry over each microdialysis fiber. Cutaneous vascular conductance (CVC) was calculated as RBC flux per mean arterial pressure, with values expressed as a percentage of maximal vasodilation ( infusion of 28 mM sodium nitroprusside). NOS inhibition reduced CVC from 75 +/- 6% maximal CVC (CVCmax) to 53 +/- 3% CVCmax in the young subjects and from 64 +/- 5% CVCmax to 29 +/- 2% CVCmax in the older subjects with a 1.0degreesC rise in core temperature. Thus the relative NO-dependent portion of cutaneous active vasodilation (AVD) accounted for similar to23% of vasodilation in the young subjects and 60% of the vasodilation in the older subjects at this level of hyperthermia (P < 0.001). In summary, NO-mediated pathways contributed more to the total vasodilatory response of the older subjects at high core temperatures. This suggests that attenuated cutaneous vasodilation with age may be due to a reduction in, or decreased vascular responsiveness to, the unknown neurotransmitter(s) mediating AVD.