Removal of a dimeric form of surfactant protein C from mouse lungs: its acceleration by reduction

Abstract

Li, Zhong-Yuan, Yasuhiro Suzuki, Mafumi Kurozumi, Hui-Qing Shen, and Chen-Xia Duan. Removal of a dimeric form of surfactant protein C from mouse lungs: its acceleration by reduction. J. Appl. Physiol. 84(2): 471–478, 1998.—Clearance of hydrophobic surfactant-associated protein C (SP-C) and its dimeric form ([SP-C]2) was investigated. SP-C and [SP-C]2 obtained from proteinosis patients were fluorescently labeled and were instilled into mouse lungs as lipid-protein complexes. [SP-C]2 was removed more slowly than SP-C, with apparent half-lives of 30 and 18 h, respectively. A significant amount of [SP-C]2 was removed as SP-C, and the conversion rate was 0.22 μg ⋅ h−1 ⋅ mouse−1. By correcting the removal as SP-C, we obtained 38 h for a possible half-life of [SP-C]2. Conversion from SP-C to [SP-C]2 seemed very slow. Decrease in glutathione (GSH) in the lung inhibited the conversion of [SP-C]2to SP-C and GSH-treatment of liposomes accelerated clearance of [SP-C]2. These results suggest that the removal of [SP-C]2 from lung is accelerated by reduction and that GSH acts as a reducing agent in the lung.