Open AccessDiurnal changes of arterial oxygen saturation and erythropoietin concentration in male and female highlanders
Author(s) -
Cristancho Edgar,
Riveros Alain,
Sánchez Armando,
Peñuela Oscar,
Böning Dieter
Publication year - 2016
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12901
Subject(s) - nocturnal , morning , erythropoietin , medicine , altitude (triangle) , circadian rhythm , hemoglobin , diurnal temperature variation , effects of high altitude on humans , hypoxia (environmental) , endocrinology , zoology , oxygen , biology , chemistry , meteorology , physics , geometry , mathematics , organic chemistry , anatomy
In Caucasians and Native Americans living at altitude, hemoglobin mass is increased in spite of erythropoietin concentrations ([Epo]) not markedly differing from sea level values. We hypothesized that a nocturnal decrease of arterial oxygen saturation (SaO 2 ) causes a temporary rise of [Epo] not detected by morning measurements. SaO 2 (continuous, finger oximeter) and [Epo] (ELISA, every 4 h) were determined in young highlanders (altitude 2600 m) during 24 h of usual daily activity. In Series I (six male, nine female students), SaO 2 fell during the night with the nadir occurring between 01:00 and 03:00; daily means (range 92.4–95.2%) were higher in females (+1.7%, P < 0.01). [Epo] showed opposite changes with zenith occurring at 04:00 without a sex difference. Mean daily values (22.9 ± 10.7SD U/L) were higher than values obtained at 08:00 (17.2 ± 9.5 U/L, P < 0.05). In Series II (seven females), only SaO 2 was measured. During follicular and luteal phases, SaO 2 variation was similar to Series I, but the rhythm was disturbed during menstruation. While daily [Epo] variations at sea level are not homogeneous, there is a diurnal variation at altitude following changes in SaO 2 . Larger hypoventilation‐dependent decreases of alveolar PO 2 decreases during the night probably cause a stronger reduction of SaO 2 in highlanders compared to lowlanders. This variation might be enlarged by a diurnal fluctuation of Hb concentration. In spite of a lower [Hb], the higher SaO 2 in women compared to men led to a similar arterial oxygen content, likely explaining the absence of differences in [Epo] between sexes.