Life-long consequences of postnatal normoxia exposure in rats raised at high altitude.

We tested the hypothesis that exposure of high-altitude (HA) rats to a period of postnatal normoxia has long-term consequences on the ventilatory and hematological acclimatization in adults. Male and female HA rats (3,600 m, Po(2) ≃ 100 Torr; La Paz, Bolivia) were exposed to normal room air [HA control (HACont)] or enriched oxygen (32% O(2); Po(2) ≃ 160 Torr) from 1 day before to 15 days after birth [HA postnatal normoxia (HApNorm)]. Hematocrit and hemoglobin values were assessed at 2, 12, and 32 wk of age.

Enhanced erythropoietin expression in the brainstem of newborn rats at high altitude.

In addition to its role in elevating red blood cell number, erythropoietin (Epo) exerts protective functions against acute and delayed degenerative diseases of the brain. Moreover, we have recently demonstrated that endogenously synthesized Epo and soluble Epo receptor (a negative regulator of Epo binding to the Epo receptor) in the central nervous system play a crucial role in facilitating the ventilatory response and acclimatization to hypoxia. Here we hypothesized that cerebral Epo in the brainstem is implicated in the process that allows cardiorespiratory acclimatization to high altitude hypoxia during the postnatal period.