Acclimatization and adaptation to high altitude in newborn rats

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At high altitude, the organism of most mammals responds with a series of adjustment that increases the transport of oxygen in the blood and its utilization by the cells. These responses include a gradual increase of ventilation, that develops over several days, due to a progressive increase of sensitivity of specialized cells sensing the decrease of blood oxygenation. Furthermore these responses varies with age (low in newborn and strong in adults), and this development is greatly influenced by environmental oxygen levels. Humans and animals raised under condition of low oxygen (such as occurring at high altitude) have a persistent and paradoxical defect in the ability of these cells to respond to low oxygen, hence their respiratory response is weaker than expected. It is one of our objective to further understand how this decrease of respiratory sensibility to low oxygen will prevent an adequate acclimatization to long-term hypoxia in adults. This question is of interest for the hundreds of millions of humans living at altitude ranging from 2500 to 4500 m worldwide. A secondary question of our research concerns the effect of low oxygen during postnatal development in rats permanently living at high altitude, in the capital-city of Bolivia, at 3600m above sea level. While responses to long-term exposure to low oxygen are well described in adults, studies in newborn are scarce, but are nonetheless critical to better understand how mammals, and men, may survive and develop into well-adapted adults at high altitude. We use rats raised at high altitude to define the contribution of high altitude hypoxia during postnatal development, a critical period for succesful reproduction. Genetic adaptation favors life at altitude, and some genetically adapted rodents are found at extremely high altitude in North America (4500 m). To understand the contribution of genetic background and during postnatal development at high altitude we will study development of respiratory control in these animals. These studies will expend our comprehension of the mechanisms underlying successful life at high altitude, a research area of long-lasting interest in physiology and respiratory biology.