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Hyperoxia Prevents
Carrageenan-Induced Enlargement of Functional Residual Lung
Capacity in Rats
B. FIŠÁRKOVÁ, M. VÍZEK
Institute of Pathological Physiology, Second Faculty of
Medicine, Charles University, and Center for Experimental
Cardiovascular Research, Prague, Czech Republic
Received December 6, 2002
Accepted May 5, 2003
Summary
Experimental pneumonia induced by intratracheal application of carrageenan or
paraquat increases the functional residual lung capacity (FRC) in rats. The
mechanism of this increase is not clear, but a decrease in PO2 may be
involved. To test this possibility, we attempted to eliminate the PO2
decrease in carrageenan-treated rats by exposing them to hyperoxia. Animals of
the first group were exposed to 7 days of hyperoxia (FIO2
0.78-0.84, group Car+O2) after intratracheal application of
carrageenan (0.5 ml of 0.7 % carageenan in saline), whereas animals of the
second group were given the same dose of carrageenan but breathed air (group
Car+A). The third group of rats was kept for seven days in hyperoxia (group O2)
and the fourth group served as controls (C). The animals were then anesthetized
and intubated and their ventilatory parameters and FRC were measured during air
breathing. Carrageenan application induced a FRC increase (Car+A 2.0±0.2 ml, C
1.6±0.1 ml), which was not seen in carrageenan-treated rats exposed to hyperoxia
(Car+O2 1.6±0.1 ml). Hyperoxia alone did not affect the value of FRC
(O2 1.5±0.1 ml). These results support the hypothesis that a decrease
in PO2 plays an important role in the carrageenan-induced increase of
FRC in rats.
Key words
Functional residual capacity • Experimental pneumonia •
Carrageenan • Chronic hyperoxia • Control of breathing
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