Characteristics of Cl− uptake in rat alveolar type I cells

AUTOR(ES)

Johnson, Meshell

FONTE

American Physiological Society

RESUMO

Although Cl− transport in fetal lung is important for fluid secretion and normal lung development, the role of Cl− transport in adult lung is not well understood. In physiological studies, the cystic fibrosis transmembrane regulator (CFTR) plays a role in fluid absorption in the distal air spaces of adult lung, and alveolar type II cells cultured for 5 days have the capacity to transport Cl−. Although both alveolar type I and type II cells express CFTR, it has previously not been known whether type I cells transport Cl−. We studied Cl− uptake in isolated type I cells directly, using either radioisotopic tracers or halide-sensitive fluorescent indicators. By both methods, type I cells take up Cl−. In the presence of β-adrenergic agonist stimulation, Cl− uptake can be inhibited by CFTR antagonists. Type I cells express both the Cl−/HCO3− anion exchanger AE2 and the voltage-gated Cl− channels CLC5 and CLC2. Inhibitors of AE2 also block Cl− uptake in type I cells. Together, these results demonstrate that type I cells are capable of Cl− uptake and suggest that the effects seen in whole lung studies establishing the importance of Cl− movement in alveolar fluid clearance may be, in part, the result of Cl− transport across type I cells.

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