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SHORT COMMUNICATION
Hypercapnia Does Not Affect Functional Residual
Capacity Enlargement Induced by Chronic Hypoxia
H. MAXOVÁ, M. VÍZEK
Institute of Pathological Physiology, Second
Faculty of Medicine, Charles University, and Center for
Experimental Cardiovascular Research, Prague, Czech Republic
Received November 2, 2001
Accepted March 22, 2002
Summary
To determine whether changes in partial pressure of CO2
participate in mechanism enlarging the lung functional residual
capacity (FRC) during chronic hypoxia, we measured FRC and
ventilation in rats exposed either to poikilocapnic (group H,
FIO2 0.1, FICO2 <0.01) or hypercapnic (group H+CO2, FIO2 0.1,
FICO2 0.04-0.05) hypoxia for the three weeks and in the controls
(group C) breathing air. At the end of exposure a body
plethysmograph was used to measure ventilatory parameters (V´E,
fR, VT) and FRC during air breathing and acute hypoxia (10 % O2
in N2). The exposure to hypoxia for three weeks increased FRC
measured during air breathing in both experimental groups (H:
3.0±0.1 ml, H+CO2: 3.1±0.2 ml, C: 1.8±0.2 ml). During the
following acute hypoxia, we observed a significant increase of
FRC in the controls (3.2±0.2 ml) and in both experimental groups
(H: 3.5±0.2 ml, H+CO2: 3.6±0.2 ml). Because chronic hypoxia
combined with chronic hypercapnia and chronic poikilocapnic
hypoxia induced the same increase of FRC, we conclude that
hypercapnia did not participate in the FRC enlargement during
chronic hypoxia.
Key
words
Functional residual capacity · Chronic hypoxia and hypercapnia ·
Chronic hypoxia · Rat
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requests
H. Maxová, Institute of Pathological Physiology, Second Faculty
of Medicine, Charles University, Plzeňská 221, 150 00 Prague 5,
Czech Republic, fax: +420 257210995, e-mail:
hana.maxova@lfmotol.cuni.cz
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