Bender P R, Groves B M, McCullough R E, McCullough R G, Huang S Y, Hamilton A J, Wagner P D, Cymerman A, Reeves J T
Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver, 80262.
J Appl Physiol (1985). 1988 Dec;65(6):2592-7. doi: 10.1152/jappl.1988.65.6.2592.
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; PIO2, 83 Torr), and after 18 days' residence on Pikes Peak (4,300 m) while breathing ambient air (PIO2, 86 Torr) and air similar to that at sea level (35% O2, PIO2, 144 Torr). In both hypoxia and normoxia, after acclimatization the femoral arterial-iliac venous O2 content difference, hemoglobin concentration, and arterial O2 content, were higher than before acclimatization, but the venous PO2 (PVO2) was unchanged. Thermodilution leg blood flow was lower but calculated arterial O2 delivery and leg VO2 similar in hypoxia after vs. before acclimatization. Mean arterial pressure (MAP) and total peripheral resistance in hypoxia were greater after, than before, acclimatization. We concluded that acclimatization did not increase O2 delivery but rather maintained delivery via increased arterial oxygenation and decreased leg blood flow. The maintenance of PVO2 and the higher MAP after acclimatization suggested matching of O2 delivery to tissue O2 demands, with vasoconstriction possibly contributing to the decreased flow.
居住在高海拔地区可能会伴随着一些适应性变化，这些变化会改变氧气输送到运动肌肉的机制。7名年龄在22±1岁的海平面居民男性，在海平面常氧环境下[吸入氧分压（PIO2）为150 Torr]、急性低压缺氧环境下（气压445 Torr；PIO2，83 Torr），以及在派克斯峰（4300米）居住18天后呼吸环境空气（PIO2，86 Torr）和类似海平面的空气（35%氧气，PIO2，144 Torr）时，进行了中度至接近最大强度的稳态自行车运动。在缺氧和常氧环境中，适应后股动脉-髂静脉血氧含量差、血红蛋白浓度和动脉血氧含量均高于适应前，但静脉血氧分压（PVO2）未改变。热稀释法测得的腿部血流量较低，但适应后缺氧状态下计算得出的动脉氧输送量和腿部耗氧量与适应前相似。适应后缺氧状态下的平均动脉压（MAP）和总外周阻力比适应前更大。我们得出结论，适应并没有增加氧输送，而是通过增加动脉氧合和减少腿部血流量来维持氧输送。适应后PVO2的维持以及更高的MAP表明氧输送与组织氧需求相匹配，血管收缩可能导致了血流量的减少。
