Hyperventilation does not increase alveolar surfactant phospholipids in the anesthetized rat.

Pulmonary distension elicits an increase of the surfactant secretion. Effects of hyperventilation on this same secretion are less precise since they were observed under particular experimental conditions. We report a study of the effects of hyperventilation on the phospholipid content of alveolar lining fluid in the rat. One hour's hyperventilation induced by addition of a dead space to the tracheal cannula of anesthetized rats did not affect the phospholipid content of broncho-alveolar lavage fluid collected in situ immediately after killing. Phospholipid content (4.82 +/- 1.39 mg.g-1 dry lung weight) did not differ significantly from that in anesthetized spontaneously breathing rats (4.00 +/- 1.09 mg.g-1 dry lung weight). Furthermore, phospholipid content was not found to increase in animals maintained at 37 degrees C for 20 min (4.43 +/- 1.30 mg.g-1 dry lung weight) or 60 min (3.55 +/- 0.88 mg.g-1 dry lung weight) after killing. In conclusion the constancy of phospholipid content can be due either to a normal secretion or to a hypersecretion with a concomitant removal.