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.