• Maarten D W Hupperets, Susan R Hopkins, Marieke G Pronk, Ivo J H Tiemessen, Nathalie Garcia, Peter D Wagner, and Frank L Powell.
• Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0623, USA.
• Respir Physiol Neurobiol. 2004 Sep 15;142(2-3):145-52.

AbstractAcclimatization to chronic hypoxia (CH) increases ventilation (V(I)) and the isocapnic hypoxic ventilatory response (HVR) over 2-14 days but hypoxic desensitization blunts the HVR after years of CH. We tested for hypoxic desensitization during the first 2 months of CH by studying five normal subjects at sea level (SL) and for 8 weeks at 3800 m (CH, PI(O(2)) approximately 90 Torr). We measured the isocapnic HVR (Delta V(I)/Delta Sa(O(2)) and tested for hypoxic ventilatory decline (HVD) by stepping Sa(O(2)) to 80% after 14 min at 90%. The HVR increased significantly after 2 days and remained significantly elevated for 8 weeks of CH. HVD was similar at SL and during 8 weeks of CH. Hence, hypoxic desensitization of the HVR does not occur after only 8 weeks of hypoxia and the increased HVR during this time does not involve changes in HVD.

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