[The effect of growth hormone on Clara cell in acute lung injury of rats].

Objective: To study the effect of growth hormone (Gh) on Clara cell in acute lung injury (ALI) rats during stress responsive stage.

Methods: One hundred and twelve male Sprague-Dawley (SD) rats were randomly divided into ALI group and recombinant human Gh (rhGh) group. The rats in two groups were subdivided into seven subgroups of different time intervals after lipopolysaccharide (LPS) injection:0 (pre-injection of LPS, acted as control group), 0.5, 1, 2, 4, 6 and 24 hours subgroups respectively. Immunohistochemistry and electron microscope were used to investigate the number and morphological changes in Clara cells in ALI rats.

Results: Half of an hour after LPS injection, ALI was induced. The extent of lung injury increased with the time increased after LPS injection,peaked at 6 hours, then the extent of lung injury began to recess. The dynamic changes in lung injury of rats in rhGh group were similar to those in ALI group, but the extent of injury was more severe than that in ALI group at different time intervals. The Clara cell counts decreased significantly 1 hour after LPS injection, reaching the lowest at 6 hours, then began to recover 24 hours after LPS injection with statistically significant difference (all P<0.01). The counts of Clara cells in rhGh group decreased more significantly than that in ALI group at different time intervals after LPS injection, especially at 24 hours.The ultrastructure of Clara cell showed significant damage 24 hours after LPS injection. Compared with ALI group,the ultrastructure of Clara cell in rhGh group were more damaged 24 hours after LPS injection.

Conclusion: rhGh could deteriorate the damage of Clara cell in acute lung injury rats induced by endotoxemia during stress response stage.