Role of NHE-1 in the proliferation and apoptosis of pulmonary artery smooth muscle cell in rats

AIM: To evaluate the role of Na⁺/H⁺ exchanger-1(NHE-1)in the proliferation and apoptosis of pulmonary artery smooth muscle cells in rats. METHODS: Twenty Wistar rats were equally randomized into the control group and 3-week hypoxic group. Intracellular pH (pHi) of the smooth muscle was determined with fluorescence measurement of the pH-sensitive dye BCECF-AM and the expression of NHE-1 mRNA was detected with RT-PCR. The primary culture of pulmonary artery smooth muscle cell in vitro was performed. In situ cell death detection kit (TUNEL) was used to study the effect of specific NHE-1 inhibitor, dimethyl amiloride (DMA), on the apoptosis of muscle cells which had intracellular acidification. RESULTS: pHi value and expression of NHE-1 mRNA of pulmonary artery smooth muscle cell were significantly higher respectively in the hypoxic group than those in the control group (P＜0.01). DMA elevated the apoptotic ratio significantly. The effect was enhanced when DMA concentration was augmented and the time was prolonged. CONCLUSION: With the function of adjusting pHi, NHE-1 may play an important role in the proliferation and apoptosis of pulmonary artery smooth muscle cells.