Fig. 4.

Mechanical ventilation induces autophagy in lung macrophages. A: mechanical ventilation activates autophagy in lung macrophages. Mice were ventilated with a low (7 ml/kg) or high tidal volume (28 ml/kg) for 2 h (n = 3 for each group). Lung macrophages were then isolated from the whole lung homogenates. Lysates from macrophages were analyzed by Western blot. Top, representative Western blots for LC3-I and LC3-II; bottom, bar graph showing the relative abundance of LC3-II protein (normalized to that of GAPDH) from 3 experiments. B: effects of alveolar macrophage (AM) depletion on mechanical ventilation-induced autophagy activation in the lung. Mice were depleted of AMs with clodronate liposomes (CLOD) or PBS (control) and then ventilated with a high tidal volume (28 ml/kg) for 2 h (n = 3 for each group). Top, representative Western blots for LC3-I and LC3-II; bottom, bar graph showing the relative abundance of LC3-II protein (normalized to that of GAPDH) from 3 experiments. *P < 0.05 vs. the control (nonventilated and nontreated) group, †P < 0.05 vs. corresponding MV group.