Acquired attenuation of chemoreceptor function in chronically hypoxic man at high altitude

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Abstract

To determine whether chronic exposure to hypoxia during adulthood produces alterations in the control of ventilation, measurements of the resting ventilatory response to hypoxia and hypercapnia, as well as ventilatory response to hypoxia during exercise, were carried out in a group of 10 long-term (3-39 yr) non-native residents of Leadville, Colo. (elevation 3100 m). A group of 8 subjects native to Leadville was also studied and 10 low altitude subjects of Denver, Colo. (elevation 1600 m) served as controls. Hypoxic ventilatory drive was measured as the shape parameter A of isocapnic ˙VE-PAo2 curves. In the non-native high altitude resident this parameter averaged 43% of the value for low altitude controls (P<0.05) denoting a diminished ventilatory response to hypoxia. The degree of attenuation was related to the length of time spent at high altitude. In the high altitude natives the parameter A averaged 9.6% of control (P<0.01). Similarly hypercapnic ventilatory drive as measured by the slope of the isoxic ˙VE-PAco2 lines was reduced in the non-native residents to 65% of control (P<0.05) and in the natives averaged 54% of control (P<0.01).

Authors

John V. Weil, Edward Byrne-Quinn, Ingvar E. Sodal, Giles F. Filley, Robert F. Grover