Objective: To study the expression of aquaporin-1 (AQP-1) in pleural mesothelial cells (PMCs) and the influence of hypertonic medium thereupon.
Methods: Rat PMCs were isolated, cultured, and divided into 2 groups: hypertonic group, cultured in hypertonic media with NaCl of different concentrations for 24 h and control group, cultured in D-MEM/F-12 medium. The 100 mmol/L NaCI group was examined at the time points 6, 12, 18, and 24 h respectively. RT-PCR and Western blotting were used to analyze the mRNA and protein expression of AQP-1.
Results: The A values of AQP-1 protein expression were 24.0 +/- 1.8, 27.8 +/- 2.4, 31.7 +/- 2.5, 89.7 +/- 6.2, and 107.7 +/- 9.3 respectively in the PMCs treated with hypertonic media with NaCl of the concentrations of 25, 50, 75, 100, and 150 mmol/L, all significantly higher than that in the control group (10.8 +/- 1.5, all P < 0.01). The A values of AQP-1 protein expression were 42.1 +/- 2.6, 78.9 +/- 3.6, 109.6 +/- 7.6, and 123.4 +/- 8.7 in the PMCs treated with hypertonic media with NaCl of the concentration of 100 mmol/L after 6 h, 12 h, 18 h, and 24 h, all significantly higher than that in the control group (12.9 +/- 1.9, P < 0. 01). The a values of AQP-1 mRNA expression were 62.6 +/- 6.4, 75.3 +/- 5.5, 122.3 +/- 11.4, 196.2 +/- 18.1, and 223.0 +/- 19.3 respectively in the PMCs treated with hypertonic media with NaCl of the concentrations of 25, 50, 75, 100, and 150 mmol/L, all significantly higher than that in the control group (23.5 +/- 2.7, all P < 0.01). The A values of AQP-1 protein expression were 83.6 +/- 6.1, 159.3 +/- 6.9, 266.2 +/- 24.1, and 196.2 +/- 15.7 in the PMCs treated with hypertonic media with NaCl of the concentration of 100 mmol/L after 6 h, 12 h, 18 h, and 24 h, all significantly higher than that in the control group (26.5 +/- 2.8, P < 0.01).
Conclusion: Hypertonic medium increases the expression of AQP-1 mRNA and protein. AQP-1 participates in the pleural fluid formation.