Effect of acute hypoxia on regional cerebral blood flow: effect of sympathetic nerve activity.

We examined 1) whether global cerebral blood flow (CBF) would increase across a 6-h bout of normobaric poikilocapnic hypoxia and be mediated by a larger increase in blood flow in the vertebral artery (VA) than in the internal carotid artery (ICA); and 2) whether additional increases in global CBF would be evident following an α1-adrenergic blockade via further dilation of the ICA and VA. In 11 young normotensive individuals, ultrasound measures of ICA and VA flow were obtained in normoxia (baseline) and following 60, 210, and 330 min of hypoxia (FiO2 = 0.11).

Conduit artery structure and function in lowlanders and native highlanders: relationships with oxidative stress and role of sympathoexcitation.

Research detailing the normal vascular adaptions to high altitude is minimal and often confounded by pathology (e.g., chronic mountain sickness) and methodological issues.