Diurnal changes of arterial oxygen saturation and erythropoietin concentration in male and female highlanders

Abstract

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 (SaO2) causes a temporary rise of [Epo] not detected by morning measurements. SaO2 (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), SaO2 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 SaO2 was measured. During follicular and luteal phases, SaO2 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 SaO2. Larger hypoventilation‐dependent decreases of alveolar PO2 decreases during the night probably cause a stronger reduction of SaO2 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 SaO2 in women compared to men led to a similar arterial oxygen content, likely explaining the absence of differences in [Epo] between sexes.

Erythropoietic effects of low‐dose cobalt application

“…The finding that the five‐day application did not have a greater EPO response than the single dose may be related to the timing of CO‐ingestion and the diurnal changes in plasma [EPO] . Under baseline conditions, we found circadian fluctuations of plasma [EPO], with low values in the morning and higher values in the afternoon and during the night as described in the literature . It should be noted that the placebo group demonstrated the most pronounce diurnal variation.…”

“…30 Under baseline conditions, we found circadian fluctuations of plasma [EPO], with low values in the morning and higher values in the afternoon and during the night as described in the literature. 31,32 It should be noted that the placebo group demonstrated the most pronounce diurnal variation. Since subjects were randomly assigned to treatment groups it is unlikely that selection bias contrib- During the day, when Co 2+ has been administered every 4 hours, continuous stimulation occurs in the 10 mg group, with higher EPO values in the afternoon (at 2 pm) and at night (at 9 pm, Figure 3D).…”

Circadian regulation of renal function

“…While the study in Uppsala was performed at an elevation of about 15 m above sea level, Cristancho et al reported EPO rhythms in men and women living at least 3 years in of Bogotá, Columbia, with an elevation more than 2600 m over sea level. EPO peaked in both genders late in the night around 4 a.m. [136]. While these studies provide potential evidence that the rhythm of circulating EPO may change at different elevations, more studies involving different populations at varying elevations are necessary to confirm these findings.…”

Genç Sporcularda Diurnal Değişkenliğin Yüksek Şiddetli Egzersiz Sonrası Toparlanmaya Etkisi

“…Başka bir deyişle, sirkadiyen ritme bağlı olarak tüm vücut fonksiyonları da gün içi ya da diurnal değişkenlikler ve salınımlar içerisindedir (Atkinson & Reilly 1996;Reilly, Atkinson & Waterhouse 1997;Rosa 2016). Bu bağlamda, diurnal ya da gün içi salınımların sportif performans düzeyi üzerinde de etkili olduğunu ve birçok fiziksel performans bileşeninin gün içerisinde değişkenlik sergilediğini gösteren çok sayıda bilimsel araştırma bulunmaktadır (Atkinson & Reilly 1996;Reilly, Atkinson & Waterhouse 1997;Reilly 2009;Rossi 2015;Thun 2015;Cristancho 2016;Ghattassi 2016;Rosa 2016).…”

“…Ancak literatürde yer alan biyolojik ritimlerle, özellikle de sirkadiyen ritimle ilgili olarak, diurnal değişkenliklerin sportif performans bileşenleri üzerindeki etkilerini inceleyen çok sayıdaki çalışmada, farklı yüklenme yöntemlerine verilen yanıtlardaki değişimler ele alınmıştır. Diğer bir deyişle, kronobiyolojik çalışmalar yüklenmeye verilen yanıtlardaki değişkenlikler üzerinde odaklanmıştır (Hill & Smith1991;Atkinson & Reilly 1996;Reilly, Atkinson & Waterhouse 1997;Deschodt & Arsac 2004;Souissi 2004;Nicolas 2008;Reilly 2009;Rossi 2015;Thun 2015;Cristancho 2016;Ghattassi 2016;Hatfield, Nicoll & Kraemer 2016;Rosa 2016). Yüklenme sonrası toparlanma sürecine ilişkin olarak diurnal değişimlerin incelendiği bilimsel araştırma sayısı ise oldukça azdır (Güneş 1998;Güvenç 2004;Nicolas 2007;Waterhouse 2007;Morris 2009).…”