Effects of simulated altitude (normobaric hypoxia) on cardiorespiratory parameters and circulating endothelial precursors in healthy subjects.
BACKGROUND
Circulating Endothelial Precursors (PB-EPCs) are involved in the maintenance of the endothelial compartment being promptly mobilized after injuries of the vascular endothelium, but the effects of a brief normobaric hypoxia on PB-EPCs in healthy subjects are scarcely studied.


METHODS
Clinical and molecular parameters were investigated in healthy subjects (n = 8) in basal conditions (T0) and after 1 h of normobaric hypoxia (T1), with Inspiratory Fraction of Oxygen set at 11.2% simulating 4850 mt of altitude. Blood samples were obtained at T0 and T1, as well as 7 days after hypoxia (T2).


RESULTS
In all studied subjects we observed a prompt and significant increase in PB-EPCs, with a return to basal value at T2. The induction of hypoxia was confirmed by Alveolar Oxygen Partial Pressure (PAO2) and Spot Oxygen Saturation decreases. Heart rate increased, but arterial pressure and respiratory response were unaffected. The change in PB-EPCs percent from T0 to T1 was inversely related to PAO2 at T1. Rapid (T1) increases in serum levels of hepatocyte growth factor and erythropoietin, as well as in cellular PB-EPCs-expression of Hypoxia Inducible Factor-1alpha were observed.


CONCLUSIONS
In conclusion, the endothelial compartment seems quite responsive to standardized brief hypoxia, possibly important for PB-EPCs activation and recruitment.
Istituto di Medicina Cardiovascolare, Centro Interuniversitario di Fisiologia Clinica e Ipertensione, University of Milan, Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Fondazione IRCCS, Milano, Italy. michele.ciulla@unimi.it
Michele M
MM
Ciulla
Michela
M
Cortiana
Ilaria
I
Silvestris
Emanuela
E
Matteucci
Elisa
E
Ridolfi
Fabrizio
F
Giofrè
Maddalena
M
Zanardelli
Roberta
R
Paliotti
Agostino
A
Cortelezzi
Alberto
A
Pierini
Fabio
F
Magrini
Maria Alfonsina
MA
Desiderio
D000531:Altitude; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry / Q000379:methods; D006339:Heart Rate / Q000502:physiology*; D017228:Hepatocyte Growth Factor / Q000097:blood; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D015656:Respiratory Mechanics / Q000502:physiology*
C066855:HGF protein, human; D017228:Hepatocyte Growth Factor