Oxygen penetration in and release from lung surfactant

The kinetics of oxygen penetration from the air into an oxygen free human BAL/saline and of its release from the oxygenated BAL/saline into a nitrogen environment was studied. Time-dependent oxygen concentration at constant temperature was monitored by recording the direct polarographic current of the second reduction wave of oxygen at a dropping mercury electrode. The obtained kinetic curves showed that not only uptake and release were quicker in BAL than in saline but also the corresponding equilibrium values were higher. Release and uptake curves in BAL were markedly different. The release was faster than the uptake but its maximal value was about 30% under the maximal uptake level. We suggest that the differences in oxygen uptake and release kinetics might contribute to explain the previously found accumulation of oxygen in BAL. The positive difference between the release and uptake kinetics at the beginning of the curves is consistent with a steady oxygen penetration through the BAL. The difference in the maximal oxygen uptake level and the maximal release level indicates a partial retention of the oxygen in the system.