BACKGROUND: Recent studies have suggested that increased glucose uptake via GLUT1 may be a major determinant of glucose utilization and extracellular matrix formation in mesangial cells. This study was to evaluate the effect of protein kinase C inhibitor on glucose transporter-1 (GLUT1) expression in cultured rat mesangial cells. METHODS: The GLUT1 expression was evaluated in mesangial cells exposed to various glucose concentrations of media (5.5 mM, 15 mM or 30 mM) and incubation times (6 hr, 24 hr or 72 hr) by semiquantitative RT-PCR and western blot analysis. The effect of protein kinase C (PKC) inhibitor, calphostin C and phorbol 12-myristate 13-acetate (PMA) on GLUT1 expression was also evaluated under the same conditions. RESULTS: The GLUT1 mRNA expressions were significantly increased in MG (15 mM) and HG (30 mM) than those in NG (5.5 mM) with incubation of 6 hr, 24 hr and 72 hr, respectively. In HG media, the GLUT1 mRNA expression with incubation of 24 hr and 72 hr were significantly increased than that with incubation of 6 hr, respectively. In HG media, the GLUT1 mRNA expressions were significantly reduced in calphostin C and PMA treated groups compared with those in untreated groups. In western blot analysis of HG media, GLUT1 proteins were identified in PMA- or calphostin C-untreated group and PMA 6 hr treated group, but not identified in PMA 24 hr treated group and in calphostin C-treated groups with incubation of 6 hr and 24 hr. CONCLUSION: PKC inhibitors decrease glucose-induced GLUT1 expression under high glucose concentration in mesangial cells. These results suggest that PKC pathway may regulate GLUT1 expression under high glucose concentration in cultured rat mesangial cells.