Vol. 276, Issue 5, L763-L768, May 1999
Effects of eosinophil granule major basic protein on
phosphatidylcholine secretion in rat type II pneumocytes
Manabu
Okumura1,2,
Hirofumi
Kai2,
Shinya
Shinozawa1,
Yoichiro
Isohama2, and
Takeshi
Miyata2
1 Department of Pharmacy,
Miyazaki Medical College, Miyazaki 889-1692; and
2 Department of Pharmacological
Sciences, Faculty of Pharmaceutical Sciences, Kumamoto University,
Kumamoto 862, Japan
Eosinophils are involved in inflammatory
diseases such as asthma. We previously reported that activated
eosinophils increased the phosphatidylcholine (PC) secretion in primary
cultures of rat type II pneumocytes. Increased PC secretion was
confirmed to be partly mediated by superoxide anions released from
activated eosinophils. However, the influence of eosinophil granule
proteins on PC secretion is unknown at present. In this study, we
determined whether eosinophil major basic protein (MBP) influences PC
secretion. MBP dose dependently increased the PC secretion in rat type
II pneumocytes without producing any cell damage. The MBP-induced increase in PC secretion was significantly reduced by preadministration of either H-7, a protein kinase inhibitor, or
1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM, a chelator of intracellular
Ca2+, but not by H-89, a protein
kinase inhibitor. Our results suggest that the MBP-induced increase in
PC secretion may provide mechanical stability and protect against lung atelectasis.
asthma; surfactant
