Effect of High Glucose on Inducible Nitric Oxide Synthase mRNA Expression and ECM Synthesis in Cultured Mesangial Cells

Objective:To elucidate the effect of high glucose on the mRNA expression of inducible nitric oxide synthase(iNOS) and nitric oxide(NO) synthesis and on extracellular matrix(ECM) synthesis in cultured human mesangial cells(MC).Methods:Cultured human mesangial cells were stimulated with lipopolysaccharide(LPS) to induce iNOS.Normal glucose condition was 5.6 mmol/L and high glucose condition was 10 mmol/L,25 mmol/L,50 mmol/L respectively. Mannitol with same osmolality was used as control.MC proliferation was assessed by means of MTT colorrnetric method. Reverse transcription-polymerase chain reaction(RT-PCR) was used to determine the activity of iNOSmRNA. The aliquot of the medium was used to determine NO by nitrate-reductase assay.Type Ⅳ collagen and fibronectin( FN ) were determined by ELISA.Results:MC proliferation was inhibited by high glucose with the increasing of concentration and duration, reaching peak at 48 h under 50 mmol/L concentration(P0.05). Mannitol with same osmolality had no significant effects on MC proliferation(P0.05). The expression of iNOSmRNA induced by LPS was up-regulated by high glucose. There were significant differences in iNOSmRNA expression between mannitol controls and glucose groups(0.145±0.036 vs 0.331± 0.023, P0.05).NO increased with glucose concentration and duration in experimental group(P0.05). Both type Ⅳ collagen and FN increased with glucose concentration and duration in experimental group(P0.05).Conclusion:High glucose up-regulates the expression of iNOSmRNA induced by LPS and increases the concentration of NO, and the expression of Type IV collagen and FN in cultured human mesangial cells.