Cl. Bai et al., GLUTATHIONE TRANSPORT BY TYPE-II CELLS IN PERFUSED RAT LUNG, American journal of physiology. Lung cellular and molecular physiology, 11(4), 1994, pp. 120000447-120000455
Glutathione (GSH) is an antioxidant that protects the lung against oxi
dative injury. Most cells rely on synthesis of GSH to maintain intrace
llular supply and only a few cell types take up intact GSH. Although i
solated type II cells from rat have a Na+-dependent uptake system that
transports GSH into the cells against a concentration gradient, it is
not known whether this occurs from the vasculature in the intact lung
or whether other cell types in the lung also transport GSH. Based on
the knowledge that gamma-glutamyl analogues of GSH are also transporte
d by the Na+-GSH transporter, a method was developed and used to study
the cell specificity of GSH uptake in perfused lung. A stable, fluore
scent GSH S-conjugate (GSH-I14) was synthesized and separated from the
original dye as analyzed by high-performance liquid chromatography. S
tudies with isolated alveolar type II cells showed that uptake of GSH-
I14 was Na+ dependent and inhibited by GSH. In addition, uptake of GSH
by the type II cells was inhibited by GSH-I14. After perfusion of the
isolated rat lung with GSH-I14, the conjugate accumulated primarily i
n the alveolar type II cell as observed by fluorescence microscopy. Th
is was confirmed by isolation of type II cells and measurement of GSH-
I14 content. Thus these results show that specificity of GSH transport
can be studied with the fluorescent derivative, GSH-I14, and that in
the isolated perfused lung type II cells can transport and concentrate
GSH-I14 from the perfusate. Quantitative fluorescence microscopy will
be required to further determine relative transport activities by oth
er cell types.