High CO2 Levels Impair Alveolar Epithelial Function Independently of pH
Figure 1
High CO2 levels impair alveolar epithelial function in rats
. (A) Isolated rat lungs were perfused for 1 h with 40 or 60 mmHg CO2 with pHe: 7.4 or pHe: 7.2 and alveolar fluid reabsorbtion (AFR) was measured as described in the experimental procedures. Graph represents the mean±SEM, (n = 5). (B) Passive movement of Na+ (closed bars) and 3H-Mannitol (open bars) was measured as described in detail in the supplementary methods. Graph represents the mean±SEM (n = 5). Differences among groups were not statistically significant. (C) Albumin flux from the pulmonary circulation into the alveolar space was determined from the fraction of fluorescein isothiocyanate (FITC)-labeled albumin, placed in the perfusate that appeared in the alveolar instillate during the experimental protocol. Graph represents the mean±SEM, (n = 5). Differences among groups were not statistically significant. (D) A three hour experiment was performed in isolated rat lungs. Lungs were perfused for 1h with 40 mmHg CO2, switched to 60 mmHg CO2 for the second hour, and back to 40 mmHg CO2 for the third hour (pHe: 7.4). Alveolar fluid reabsorption (AFR) was measured as described in the experimental procedures. Graph represents the mean±SEM of 5 independent experiments. Bars in panels A, B and C represent the mean from different groups of animals. Bars in panel D represent the mean of single samples from the same group of animals. pHe: extracellular pH. *p<0.05; **p<0.01.