Okamoto M, Etani H, Yagita Y, Kinoshita N, Nukada T
Department of Cardiovascular Medicine and Institute for Clinical Research, Osaka-Minami National Hospital, Kawachinagana, Osaka, Japan.
Gerontology. 2001 May-Jun;47(3):131-5. doi: 10.1159/000052786.
Nitric oxide is pivotal in endothelially dependent vasodilatory regulation. An association of endothelial dysfunction with aging has been documented in the forearm and coronary vascular beds. However, the influence of aging in the human cerebral circulation, where regulation is particularly complex, is incompletely understood.
We systematically administered L-arginine, a precursor of nitric oxide, to evaluate the influence of aging on nitric oxide-mediated cerebral vasomotor regulation.
Among healthy volunteers, 20 older subjects (10 men, 10 women; age: 70.2 +/- 2.8 years) and 22 younger subjects (10 men, 12 women; age: 28.8 +/- 1.9 years) received intravenous infusions of L-arginine monochloride (500 mg/kg) over 30 min. Hemodynamic parameters were monitored continuously during and after infusion. The cerebral vasomotor response was estimated by transcranial Doppler sonography of the right middle cerebral artery.
Infusion of saline as a control brought little change in the mean blood pressure, heart rate or cerebral blood flow velocity in either group. On administration of L-arginine, cerebral blood flow velocity increased and mean blood pressure decreased. After completion of infusion, both parameters rapidly normalized. While reduction of mean blood pressure did not differ between older and younger groups, the cerebral circulation in the older group showed a blunted, smaller, and more easily saturated vasomotor response compared to the younger group, though both groups had similar baseline values.
Our results indicate a diminished nitric oxide-mediated cerebral vasomotor response in aging subjects. Additionally, transcranial Doppler sonography can be used to reliably evaluate age-related changes in the physiologic responses of the human cerebral circulation.
一氧化氮在内皮依赖性血管舒张调节中起关键作用。前臂和冠状动脉床已证实内皮功能障碍与衰老有关。然而，在调节特别复杂的人类脑循环中，衰老的影响尚未完全了解。
我们系统地给予一氧化氮前体L-精氨酸，以评估衰老对一氧化氮介导的脑血管舒缩调节的影响。
在健康志愿者中，20名老年受试者（10名男性，10名女性；年龄：70.2±2.8岁）和22名年轻受试者（10名男性，12名女性；年龄：28.8±1.9岁）在30分钟内静脉输注一氯化L-精氨酸（500mg/kg）。输注期间和之后连续监测血流动力学参数。通过右侧大脑中动脉的经颅多普勒超声估计脑血管舒缩反应。
作为对照输注生理盐水，两组的平均血压、心率或脑血流速度几乎没有变化。给予L-精氨酸后，脑血流速度增加，平均血压降低。输注完成后，两个参数迅速恢复正常。虽然老年组和年轻组平均血压的降低没有差异，但与年轻组相比，老年组的脑循环显示出血管舒缩反应减弱、幅度较小且更容易饱和，尽管两组的基线值相似。
我们的结果表明，衰老受试者中一氧化氮介导的脑血管舒缩反应减弱。此外，经颅多普勒超声可用于可靠地评估人类脑循环生理反应中与年龄相关的变化。
