[Response of pulmonary surfactant and air-blood barrier to general acute hypothermia].

Male rats weighing 235-350 g were subjected to cooling for 4-6 hours at -20 degrees C. The lungs of the supercooled animals developed interstitial and intraalveolar edema, focal atelectases and local hemorrhages. It was shown that under overall acute hypothermia the following processes occur in the lungs: 1/local impairment of the air-blood barrier integrity due to hydropic dystrophy and degeneration of type I alveolocytes and endotheliocytes; 2/disintegration, aggregation and membrane lysis of the alveolar surfactant which underlie atelectases; 3/accumulation of the surface active material in the interstice of the interalveolar septa both because of elimination of disintegrated surfactant by type I alveolocytes and as a result of phospholipid secretion from the basal side of type II alveolocytes; 4/an increase in functional activity of type II alveolocytes and alveolar macrophages.