Mechanisms and sequelae of increased alveolar fluid clearance in
hyperoxic rats.
Yue, Gang, and Sadis Matalon.
Departments of Anesthesiology, Physiology and Biophysics and
Pediatrics
APStracts 3:0191L, 1996.
We instilled four ml of isotonic fluid, containing trace amounts of
fluorescently labelled dextran (MW=150 kDa) in the lungs of rats
exposed to either 85% O2 for 7 d or 85% O2 for 7 d and 100% O2 for 3
d. We withdrew the fluid every h for a 3 h period and calculated
alveolar fluid clearance (AFC) from changes in dextran concentration.
Three h post-instillation, AFC values in the control and the two
hyperoxic groups were 51+/-1, 63+/-2* and 62 +/-3* respectively (% of
instilled volume; means+/- 1 SEM; n>/= 5; *= p <0.05).
Addition of either 1 mM amiloride or N-ethyl-N-isopropyl amiloride
(EIPA) in the instillate decreased the AFC values in all groups 3 h
later to about 30% of instilled volume. Instillation of phenamil, an
irreversible blocker of epithelial Na+ channels into the lungs of
rats exposed to 85% O2 for 7 d and 100% O2 for 2 d, resulted in a
significant increase of their extravascular lung fluid volumes 24 h
later. These results demonstrate the existence of EIPA-inhibitable
Na+ channels in alveolar epithelial cells in vivo and indicate that
an increase in Na+ transport plays an important role in limiting the
amount of alveolar edema in oxygen-damaged lungs.
Received 8 July 1996; accepted in final form 11 October 1996.
APS Manuscript Number L207-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996