Objective To investigate the effects of endothelin 1 (ET 1) on mesangial cell proliferation in vitro Methods Antisense oligodeoxynucleotide (As ODN) and its control sequences, sense (Se ODN) and mismatch (Mis ODN) oligodeoxynucleotides, targeting preproendothelin 1 (ppET 1) mRNA were delivered into cultured human mesangial cells (HMC) with lipofectin mediated gene transfer method The cytotoxicity of lipofectin was determined with lactate dehydrogenase (LDH) release assay The efficiency of ODNs transfer into HMC was examined with biotinylated As ODN staining The effect of As ODN on expression of ppET 1 mRNA was analyzed with semi quantitative reverse transcription polymerase chain reaction (RT PCR) The action of As ODN on HMC ET 1 secretion was tested by radioimmunoassay (RIA) The influence of As ODN on HMC proliferation was evaluated with MTT method Results As ODN was transferred into HMC with lipofectin without any impairment of cell viability The ppET 1 mRNA expression, the ET 1 secretion and the cell proliferation were inhibited by As ODN transferred into HMC, while Se ODN and Mis ODN transfered into HMC did not show any effects on all of these Conclussion Decrease of ET 1 secretion by HMC, caused by the down regulation of ppET 1 mRNA expression after As ODN transfer, led to inhibition of HMC proliferation These results suggest ET 1 is one of the autocrine growth factors of HMC, and may play an important role in the pathogenesis of proliferative glomerulonephritis Objective To investigate the effects of endothelin 1 (ET 1) on mesangial cell proliferation in vitro Methods Antisense oligodeoxynucleotide (As ODN) and its control sequences, sense (Se ODN) and mismatch (Mis ODN) oligodeoxynucleotides, targeting preproendothelin 1 mRNA were delivered into cultured human mesangial cells (HMC) with lipofectin mediated gene transfer method The cytotoxicity of lipofectin was determined with lactate dehydrogenase (LDH) release assay The efficiency of ODNs transfer into HMC was examined with biotinylated As ODN staining The effect of As ODN on expression of ppET 1 mRNA was analyzed with semi quantitative reverse transcription polymerase chain reaction (RT PCR) The action of As ODN on HMC ET 1 secretion was tested by radioimmunoassay (RIA) The influence of As ODN on HMC proliferation was evaluated with MTT method Results As ODN was transferred into HMC with lipofectin without any impairment of cell viability The ppET 1 mRNA expression, the ET 1 secretion and the cell proliferation were inhibited by As ODN transferred into HMC, while Se ODN and Mis ODN transfered into HMC did not show any effects on all of these Conclussion Decrease of ET 1 secretion by HMC, caused by the down regulation of ppET 1 mRNA expression after As ODN transfer, led to inhibition of HMC proliferation these results suggest ET 1 is one of the autocrine growth factors of HMC, and may play an important role in the pathogenesis of proliferative glomerulonephritis