5-Hydroxytryptamine-induced proliferation of pulmonary artery smooth muscle cells are extracellular signal-regulated kinase pathway dependent

Aim:To investigate the effect of 5-hydroxytryptamine transporter(5-HTT)inhibi-tor fluoxetine and antisense oligodeoxynucleotide(ODN)to extracelluar signal-regulated kinases(ERKs)on pulmonary arterial smooth muscle cells(PASMCs)proliferation induced by 5-HT.Methods:Liposomal transfection was used tointroduce ODNs to ERK1/2 into cultured rat PASMCs and the transfection effi-ciency was measured by observing the uptake of the fluorecein isothiocynate(FITC)-labeled antisense ODN in PASMCs.The effects of 5-HTT selective inhibi-tor fluoxetine and ODNs on the proliferation of PASMCs were evaluated by cellnumber counting and cell cycle analysis,and measured by microculture tetrazo-lium(MTT)assay and flow cytometry(FCM),respectively.Results:Liposomesmediated the transfection of ODNs into PASMCs with high efficiency.MTTassay showed fluoxetine(10μmol/L,1 μmol/L,and 100 nmol/L)concentrationdependently inhibited the proliferation of PASMCs induced by 5-HT(1 μmol/L)invitro.The proliferation rate of PASMCs by 5-HT was significantly inhibited bypretreatment with ERK1/2 antisense ODN(0.2μmol/L)from 251%±18% to 86%±5%(P<0.01).Flow cytometric analysis of cell cycle distribution showed that theincrease of 5-HT induced S phase fraction(SPF)and proliferation index(PI)weresignificantly inhibited by fluoxetine(1μmol/L)or antisense ODN with SPF from36%±4% to 26%±3% and 24%±4%,and PI from 34%±2% to 29%±2% and 24%±2%,respectively.Conclusion:5-HTT mediates the mitogenic effect of 5-HT onPASMCs and the proliferation of PASMCs induced by 5-HT is dependent onERKs signal pathway.