Shaoming Huang

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Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance.(More)
Cerebral blood flow increases at high altitude, but the mechanism of the increase and its role in adaptation to high altitude are unclear. We hypothesized that the hypoxemia at high altitude would increase cerebral blood flow, which would in turn defend O2 delivery to the brain. Noninvasive Doppler ultrasound was used to measure the flow velocities in the(More)
Maximal O2 uptake provides an index of the integrated functioning of the O2 transport system. Whether lifelong high altitude residents have greater maximal exercise capacities than acclimatized newcomers is of interest for determining whether years to generations of high altitude exposure influence maximal O2 uptake and, if so, what components of O2(More)
Residence at high altitude could be accompanied by adaptations that alter the mechanisms of O2 delivery to exercising muscle. Seven sea level resident males, aged 22 +/- 1 yr, performed moderate to near-maximal steady-state cycle exercise at sea level in normoxia [inspired PO2 (PIO2) 150 Torr] and acute hypobaric hypoxia (barometric pressure, 445 Torr;(More)
Decreased maximal O2 uptake (VO2max) and stimulation of the sympathetic nervous system have been previously shown to occur at high altitude. We hypothesized that tachycardia mediated by beta-adrenergic stimulation acted to defend VO2max at high altitude. Propranolol treatment beginning before high-altitude (4,300 m) ascent reduced heart rate during maximal(More)
The measurement of peripheral blood flow by plethysmography assumes that the cuff pressure required for venous occlusion does not decrease arterial inflow. However, studies in five normal subjects suggested that calf blood flow measured with a plethysmograph was less than arterial inflow calculated from Doppler velocity measurements. We hypothesized that(More)
Arterial O2 saturation (Sao2) decreases in hypoxia in the transition from rest to moderate exercise, but it is unknown whether other several weeks at high altitude SaO2 in submaximal exercise follows the same time course and pattern as that of ventilatory acclimatization in resting subjects. Ventilatory acclimatization is essentially complete after(More)
Persons with chronic mountain sickness (CMS) hypoventilate and are more hypoxemic than normal individuals, but the cause of the hypoventilation is unclear. Studies of 14 patients with CMS and 11 healthy age-matched control subjects residing in Lhasa, Tibet, China (3,658 m) were conducted to test the hypothesis that hypoventilation, blunted hypoxic(More)
We found that respiratory measurements in Chinese visitors to Colorado differed from those in height- and weight-matched Western residents of Denver, Colo., in the following ways (p less than 0.05): The Chinese had higher respiratory frequencies (15.5 +/- 0.93 vs. 11.4 +/- 0.85 breaths/min), lower tidal volumes (530 +/- 35.9 vs. 693 +/- 477.7 ml), lower(More)
Cerebral blood flow increases with acute exposure to high altitude, but the effect of hypoxia on the cerebral circulation at rest and during exercise appears influenced by the duration of high-altitude exposure. To determine whether internal carotid artery flow velocity increased with exercise in long-term residents of high altitude and whether resting(More)