To observe the effect of seawater stimulation on the secretion of inflammatory factors and the expression of STE20/SPS1-related proline/alanine-rich kinase (SPAK) in lung tissue of rats with seawater inhalation induced acute lung injury.

Sprague-Dawley (SD) rats were randomly divided into 5 groups: control group, 1 h, 3 h, 6 h and 12 h seawater challenged groups(n=5). After challenged by endotracheal instillation of seawater to establish lung injury models, the lung tissues samples were collected and the changes of lung tissue wet dry ratio, pathology, inflammatory factors TNF-α, IL-1β and SPAK transcription and translation were detected according to the plan.

Inhalation of seawater could immediately cause a drop of blood oxygen pressure and an increase of carbon dioxide pressure. The pathological results showed that the alveolar structure was destroyed, the alveolar wall was broken and became thicken, and neutrophil infiltration, red blood cell leakage occurred. ELISA tests showed that seawater could induce the secretion of TNF-α and IL-1β. We also detect the expression of SPAK, and the results showed that the expression of SPAK increased significantly, up to 2.7 times (P<0.01), and then decreased gradually with the recovery of lung injury. Immunohistochemical staining showed that the elevated expression of SPAK was widely distributed in the cytoplasm and nucleus.

Challenged by the hypertonic stimulation of sea water, lung cells could increase the expression of SPAK through transcription and translation, and then participate in the modulating inflammatory response, which aggravates the degree of lung injury.