ENHANCED NA-LIQUID INTERFACE CULTURE SYSTEM( TRANSPORT IN AN AIR)

Use of the air-liquid interface culture technique has produced improve d morphological differentiation of rodent, canine, and human tracheal epithelia. We have investigated the effect of this culture technique o n ion transport activities of cultured canine bronchial epithelia. The se cells were isolated from excised airways by enzymatic digestion and plated on permeable collagen membrane substrates. All cultures were m aintained utilizing standard culture techniques, by bathing both apica l and basolateral sides with hormone supplemented, serum-free media un til confluent (days 4-6). Half of the cultures were converted to air-l iquid interface cultures (ALIC) by gentle aspiration of the apical med ium and half were continued under standard technique culture (STC) con ditions. After three additional days, preparations cultured under both conditions were mounted in modified Ussing chambers where bioelectric properties were measured under short-circuit conditions. Mean short-c ircuit current (I(sc)) was significantly greater in ALIC (-91.3 +/- 7. 84 muA/cm2) than in STC (-54.8 +/- 5.03 muA/cm2). The sodium channel b locker, amiloride, reduced I(sc) by 68.4 +/-5.0% in STC and by 84.8 +/ - 3.0% in ALIC. Na-22 and Cl-36 fluxes confirmed the presence of enhan ced sodium absorption in ALIC when compared with STC. The depth of the apical fluid, measured by microelectrodes during ALIC, was approximat ely 15 mum. Studies of cellular metabolism demonstrated a shift in met abolism from an anaerobic to an oxidative pattern in ALIC. This change in the pattern of metabolism suggests that the ALIC technique enhance d sodium transport in canine bronchial epithelia by increasing oxygen delivery to the epithelium.