Microcirculatory changes during chronic adaptation to hypoxia

Microcirculatory changes in the window chamber preparation in Syrian golden hamsters, secondary to chronic hypoxia adaptation, are presented herein. Adaptation was attained by keeping animals in a 10% oxygen environment for 1 wk and 5% the following week. The following groups were studied: group 1, adapted to chronic hypoxia and kept in a 5% oxygen environment throughout the experiment; group 2, adapted to chronic hypoxia and kept in a 21% oxygen environment 24 h before and during the experiment; and group 3, control. Adaptation caused venule enlargement and hematocrit increase (68.6 ± 2.44 in group 1, 70 ± 2.66 in group 2, and 43.27 ± 2.30 in group 3; P < 0.05). Whereas heart rate decreased in adapted animals, blood pressure remained constant. Group 1 presented alkalosis, hypocapnia, and hypoxemia. The adapted groups had decreased blood flow velocity in arterioles and veins. We found no difference in microvasculature oxygen tension between groups 2 and 3; however, the number of capillaries with flow was ...