INCREASED OXIDATIVE-METABOLISM IN COW TRACHEAL EPITHELIAL-CELLS CULTURED AT AIR-LIQUID INTERFACE

Airway epithelial cells cultured at the air-liquid interface possess h ighly differentiated functions and structures compared with the cells cultured under immersion. We examined the oxidative metabolism and gly colysis in cow tracheal epithelial cells on Days 3, 6, 10, and 13, cul tured under three different conditions: (1) immersion culture on porou s filters with apical and basolateral feeding (IM), (2) air-exposed cu lture on porous filters with basolateral feeding, i.e., air-liquid int erface culture (AI), and (3) conventional immersion culture in plastic dishes with apical feeding (DI). Lactate production was less in AI th an in IM and DI on Day 3 through Day 13, whereas cellular adenosine tr iphosphate content and basal O-2 consumption were greater. Ouabain-sen sitive and ouabain-insensitive O-2 consumption, and the uncoupled O-2 consumption were also greater in AI, Cytosolic lactate dehydrogenase a ctivities on Day LO were lower in AI, whereas alpha-ketoglutarate dehy drogenase activities were higher. The increased oxidative metabolism i n AI was more pronounced at the late phase of culture (Days 10 and 13) . In contrast, glycolysis remained elevated during the experiment in I M and DI. These data suggest that (1) AI begins to promote oxidative m etabolism from growth phase by the provision of adequate oxygenation, anti then further shifts to oxidative metabolism with differentiation; and (2) apical feeding may be responsible fur the disturbance of the development of the oxidative metabolism.