Effects of calf serum and platelet-derived growth factor on sodium hydrogen antiporter activity and cell proliferation of pulmonary artery smooth muscle cells

Objective:To explore the effects of calf serum and plateletderived growth factor (PDGF) on the expression and activity of sodium hydrogen antiporter1 (NHE1) of pulmonary artery smooth muscle cells (PASMCs) in rats,and their role in PASMCs proliferation.Methods:PASMCs were cultured in vitro.After the exposure of PASMCs to 10% calf serum and PDGF for 24 hours,the expression of NHE1 mRNA was determined with reverse transcriptionpolymerase chain reaction(RTPCR),intracellular pH(pHi) was measured with fluorescent probeBCECF, 22 Na and 3HTdR incorporation were determined respectively.The effect of NHE1 specific inhibitor--EIPA on the apoptotic rates of PASMCs was studied with reverse transcriptionpolymerase chain reaction(TUNEL) in situ cell apoptosis kit.Results:Compared with the growth arrested cells,NHE1 mRNA,pHi value, 3HTdR and 22 Na incorporation significantly increased in PASMCs exposed to 10% serum and PDGF.10% calf serumtreated cells had higher NHE1 mRNA level,and 22 Na and 3H incorporation than PDGFtreated cells.EIPA significantly elevated the apoptotic ratio in PASMCs.The effect was enhanced when EIPA concentration increased and the exposure time prolonged.Conclusions:Serum and PDGF regulate the expression and activation of NHE1 in PASMCs,and induce intracellular alkalization consequently.These effects may be important in PASMCs proliferation.