Effects of cardiogenic edema fluid on ion and fluid transport in the adult lung

We have previously shown that cardiogenic pulmonary edema fluid (EF) increases [Na.sup.+] and fluid transport by fetal distal lung epithelia (FDLE) (Rafii B, Gillie DJ, Sulowski C, Hannam V, Cheung T, Otulakowski G, Barker PM and O'Brodovich H. J Physiol 544: 537-548, 2002). We now report the effect of EF on [Na.sup.+] and fluid transport by the adult lung. We first studied primary cultures of adult type II (ATII) epithelium and found that overnight exposure to EF increased [N.sup.+]. transport, and this effect was mainly due to factors other than catecholamines. Plasma did not stimulate [N.sup.+]. transport in ATII. Purification of EF demonstrated that at least some agent(s) responsible for the amiloride-insensitive component resided within the globulin fraction. ATII exposed to globulins demonstrated a conversion of amiloride-sensitive short-circuit current ([I.sub.SC]) to amiloride-insensitive L~ with no increase in total [I.sub.SC]. Patch-clamp studies showed that ATII exposed to EF for 18 h had increased the number of highly selective Nan channels in their apical membrane. In situ acute exposure to EF increased the open probability of [N.sup.+].-permeant ion channels in ATII within rat lung slices. EF did increase, by amiloride-sensitive pathways, the alveolar fluid clearance from the lungs of adult rats. We conclude that cardiogenic EF increases [N.sup.+]. transport by adult lung epithelia in primary cell culture, in situ and in vivo. pulmonary edema fluid: alveolar type ii epithelium; sodium channels; lung fluid clearance