EPO, red cells, and serum transferrin receptor in continuous and intermittent hypoxia.
OBJECTIVE
Erythropoietic response in 10 healthy nonsmoking volunteers exposed to normobaric hypoxia continuously or intermittently 12 h daily for 7 d was evaluated in a randomized cross-over study.


METHODS
An oxygen content of 15.4% corresponding to an altitude of 2500 m was created by adding nitrogen into room air in a flat. Venous blood samples for hemoglobin (Hb), hematocrit (Hct), reticulocytes, serum erythropoietin (S-EPO), red cell 2,3-diphosphoglycerate (2,3-DPG), serum ferritin (S-Ferrit), and serum soluble transferrin receptor (S-TransfR) were drawn at 8:00 a.m.


RESULTS
S-EPO was increased from baseline values of 22.9+/-9.6 and 20.5+/-10.1 U x L(-1) to 40.7+/-12.9 (P < 0.05) and 35+/-14.3 U x L(-1) (P < 0.05) after the first night in continuous and intermittent hypoxia, respectively, and remained elevated throughout both exposures. Hb and Hct values did not show any significant changes. Red cell 2,3-DPG rose from baseline a value of 5.0+/-0.8 to 5.9+/-0.7 mmol x L(-1) (P < 0.05) after the first day in continuous hypoxia and from 5.2+/-0.7 mmol x L(-1) to 6.1+/-0.5 mmol x L(-1) on day 3 (P < 0.05) during intermittent hypoxia. The reticulocyte count rose significantly (P < 0.05) after 5 d in both experiments. S-transferrin receptor level rose significantly from 2.2+/-0.4 and 2.1+/-0.5 mg x L(-1) to 2.6+/-0.5 mg x L(-1) and 2.3+/-0.6 mg x L(-1) on day 5 (P < 0.05), to 2.7+/-0.5 mg x L(-1) and 2.5+/-0.6 mg x L(-1) on day 7 (P < 0.05) under continuous and intermittent hypoxia, respectively.


CONCLUSIONS
We suggest that intermittent exposure to moderate normobaric hypoxia 12 h daily for 1 wk induces a similar stimulation of erythropoiesis as continuous exposure.
Koistinen
P O
PO
Health Center Hospital of Oulu, Finland. Pentti.Koistinen@ouka.fi
Rusko
H
H
Irjala
K
K
Rajamäki
A
A
Penttinen
K
K
Sarparanta
V P
VP
Karpakka
J
J
Leppäluoto
J
J
D000328:Adult; D018592:Cross-Over Studies; D004912:Erythrocytes; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D008297:Male; D011897:Random Allocation; D011990:Receptors, Transferrin / Q000097:blood*
D011990:Receptors, Transferrin; D004921:Erythropoietin