Abstract
The influence of high glucose concentration on proliferation, cell cycle and fibronectin (FN) accumulation in cultured normal rat kidney (NRK) cells was studied. Quiescent cells were cultured in RPMI 1640 medium containing 0.5% fetal calf serum in the presence of 5mM glucose, 30mM glucose or 5mM glucose plus 25mM mannitol for 24h.(3H) thymidine incorporation was not changed in the 30-mM glucose condition. In addition, the cell cycle of these cells was not altered in the same condition. However, measurement of FN accumulation by ELISA showed increased concentration of FN in the supernatant of NRK cells grown in the 30-mM glucose condition. Five mM glucose plus 25mM mannitol did not stimulate FN accumulation as the control condition did. Western blot analysis revealed that 30mM glucose stimulated PKC α expression in the membrane fractions of these cells, whereas 5mM glucose plus 25mM mannitol did not stimulate PKCa expressions control conditions did. On the other hand, 5, μM or 10, μM H-7 and 50nM or 100nM staurosporine (protein kinase C inhibitors), suppressed FN accumulation induced by 30mM glucose. These results suggest that high blood glucose concentration may play an important role in the expansion of the interstitium in diabetic nephropathy.
