Glycolysis is not required for fluid homeostasis in isolated rabbit lungs

We investigated whether glycolysis was necessary to maintain the integrity of vascular endothelial and alveolar epithelial barriers in continually weighed isolated rabbit lungs. Lungs were perfused with a cell-free buffered salt solution, and glycolysis was inhibited with a glucose analogue (alpha-methyl glucoside, alpha-MG) or one of two glycolysis inhibitors (iodoacetic acid, IAA, or NaF). Fluid filtration rates (FFR's, the change in lung weight/time) in response to a 7.5-min zone 3 hydrostatic stress (pulmonary arterial and venous pressures raised from 8 to 15 cmH2O, alveolar pressure kept constant at 4 cm on the deflation limb) were repeatedly measured for 120 min after which the lungs were lavaged. The total protein concentration was measured in the bronchoalveolar lavage fluid (BALP). Lactate production was measured to verify inhibition of glycolysis. Lower concentrations of IAA and alpha-MG eliminated lactate production but did not affect FFR or BALP. NaF also had no effect on the FFR or BALP. Only high concentrations of IAA increased FFR and BALP, seemingly by causing nonspecific membrane injury that was unrelated to its specific effects on glycolysis. The glycolytic pathway for energy production is not necessary to maintain the integrity of the pulmonary endothelial-epithelial barrier.