Objective: To explore the effects of tanshinone IIA on the activity of aquaporin-5 (AQP5) in human alveolar epithelial cells (A549) after seawater exposure and its possible mechanism.
Methods: Routinely cultured A549 cells were divided into different groups according to different content of seawater: blank control group, 15%, 25%, 50%, 75%, 100% seawater groups; they were divided into different groups according to the duration of exposure to 25% seawater: blank control group, 1, 4, 8 hours groups; they were also divided into different groups according to concentration of tanshinone IIA and exposed to seawater for 4 hours: blank control group, 25% seawater group, 25, 50, 75, 100 μg/ml tanshinone IIA intervention groups. The expressions of AQP5 were respectively assayed by Western blotting and immunohistochemistry.
Results: The results of Western blotting showed that the expressions of AQP5 were remarkably higher at 8 hours of exposure to seawater in 25% and 50% seawater groups than those in blank control group (1.053±0.231, 1.116±0.316 vs. 0.101±0.081, both P<0.05); the expression of AQP5 in 1-hour group showed a slight increase compared with blank control group (0.306±0.125 vs. 0.288±0.098, P>0.05), that in 4-hour group was increased significantly (1.423±0.377, P<0.01), and in 8-hour group (1.507±0.461) it was slightly higher than that in 4-hour group without statistical significance. The AQP5 expression was significantly lower in tanshinone IIA 25 μg/ml and 50 μg/ml intervention groups than that in 25% seawater group (0.580±0.186, 0.499±0.172 vs. 1.013±0.287, both P<0.05). Immuno-histochemistry showed that the expression of AQP5 was markedly up-regulated after A549 cells were stimulated with 25% seawater for 4 hours as compared with blank control group (7.21±0.78 vs. 0.41±0.07, P<0.01), but intervention of tanshinone IIA significantly inhibited the up-regulation of AQP5 expression (3.02±0.23) induced by 25% seawater (P<0.05).
Conclusion: The experimental results showed that tanshinone IIA is innocuous to A549 at a dosage of 25 μg/ml, and it can decrease the overexpression of AQP5 induced by seawater.