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Chemoreflexes : A Major Component of Adaptation to High Altitude/Hypoxic Environment
Author(s) -
Richalet JeanPaul,
Voituron Nicolas,
Hermand Eric,
Jeton Florine,
Lhuissier François J
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.841.9
Subject(s) - hypoxic ventilatory response , hypoxia (environmental) , effects of high altitude on humans , hypercapnia , peripheral chemoreceptors , biology , medicine , endocrinology , chemoreceptor , respiratory system , receptor , chemistry , anatomy , oxygen , organic chemistry
The decrease in O 2 pressure in hypoxia, either at high altitude or in disease, induces physiological responses mediated through oxygen sensing systems. Among those responses, chemoreflexes play a major role, especially during the initial phase of exposure to hypoxia. Peripheral chemoreceptors (carotid bodies) and central receptors (retrotrapezoid nucleus) are sensitive to hypoxia and hypercapnia and modulate the activity of the Respiratory rhythm generator. Our aim was to determine the role of erythropoietin (Epo) on those mechanisms in two animal models: transgenic anemic mice under‐expressing Epo (EpoTagh), and the Pika (Ochotona curzoniae) a lagomorph genetically adapted to high altitude on the Tibetan plateau. We showed that Epo are necessary for ventilatory acclimatization in EpoTagh mice and that nNOS and NMDA receptors are overexpressed in the medulla of Pikas. In humans, the sensitivity to hypoxia is a determinant factor for acclimatization to high altitude. A prospective cohort study on 1017 subjects has shown that the ventilatory response to hypoxia at exercise is predictive of the occurrence of severe high altitude illnesses (SHAI). From clinical evaluation and physiological response to hypoxia measured during a hypoxia exercise test, a predictive score of SHAI was calculated, which allowed the detection of high‐risk subjects. Instability of the control of ventilation has been evidenced during exercise in hypoxia, with oscillations of ventilation with a period of 11–12 seconds. The mechanisms of this instability is linked to the gain of the O 2 and CO 2 response, as well as other factors such as dead space and cardiac output. Support or Funding Information Laboratory of Excellence GrEx