Hyperoxic effects on alveolar sodium resorption and lung Na-K-ATPase

Ethan P. Carter, O. Douglas Wangensteen, Jordan Dunitz, David H. Ingbar

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25 Scopus citations


Active Na+ transport by the alveolar epithelium keeps alveoli relatively dry. Hyperoxia increases epithelial permeability, resulting in pulmonary edema. We sought to determine whether active Na+ resorption from the air spaces and Na-K-ATPase activity increased in rats exposed to >95% O2 for 60 h. The permeability x surface area products for unidirectional resorption of alveolar [14C]sucrose (PS(sucrose)) and 22Na+ (PS(Na+)) were measured in isolated, perfused rat lungs immediately after hyperoxia and after 3 and 7 days of recovery in room air. At 60 h of hyperoxia, the mean PS(sucrose) and PS(Na+) increased from 6.71 ± 0.8 x 10-5 to 12.6 ± 1.6 x 10-5 cm3/s (P = 0.029) and from 23.6 ± 1.1 x 10-5 to 31.0 ± 1.6 x 10- 5 cm3/s (P < 0.008), respectively. However, the values in individual rats ranged widely from no change to nearly a fourfold increase. Subgroup analysis revealed that benzamil- or amiloride-sensitive (transcellular) PS(Na+) was significantly reduced in the exposed lungs with normal PS(sucrose) but was maintained in the lungs with high PS(sucrose). By day 3 of recovery, mean Na+ and sucrose fluxes returned to values similar to control. Na-K-ATPase membrane hydrolytic maximal velocity (V(max)) activity fell significantly immediately after hyperoxic exposure but recovered to normal values by day 3 of recovery. The Na-K-ATPase β1-subunit antigenic signal did not significantly change, whereas the α1-subunit levels increased during recovery. In summary, there was a heterogeneous response of different rats to acute hyperoxia. Hyperoxia led to complex, nonparallel changes in Na+ pump antigenic protein, hydrolytic activity, and unidirectional active Na+ resorption. Active Na+ transport was differentially affected, depending on degree of injury, but permeability and transport normalized by day 3 of recovery.

Original languageEnglish (US)
Pages (from-to)L1191-L1202
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Issue number6 17-6
StatePublished - 1997


  • Acute lung injury
  • Amiloride
  • Benzamil
  • Pulmonary edema
  • Rat
  • Sodium pump
  • Sodium-potassium-adenosinetriphospharase


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