Abnormal molecular weight profile of urinary protein in rats with streptozotocin-induced diabetes

A quantitative analysis of the molecular weight (MW) profile of urinary protein by SDS-PAGE was performed in streptozotocin (STZ)-injected, non-ketotic diabetic rats (DM group), diabetic rats receiving dipyridamole (DM-DIP group), normal rats (C group) and STZ-injected rats with near-normal glycemia due to insulin treatment (DM-INSULIN group). In the DM group, decrease of a small MW protein (SMWP) (MW 19.5 k) was found at 2.5 weeks, and an increase of larger MW proteins (LMWP) (MW 68 [albumin], 55 and 29 k) together with a decrease of SMWPs (MW 19.5 and 15 k) was found at 15 weeks, as compared to the C group: the MW profile of urinary protein in the DM-INSULIN and C groups was indistinguishable. At 15 weeks, creatinine clearance (Ccr) was significantly depressed and an increase in the mesangial matrix with electron dense deposits was evident in the DM group. The urinary protein abnormalities were partially corrected and the reduction of Ccr was absent in the DM-DIP group with no effect on glomerular morphology. STZ-induced diabetes in rats is accompanied by a reduction of urinary SMWP, and a subsequent increase of LMWP and depression of Ccr: dipyridamole ameliorates urinary protein abnormalities and prevents the reduction of Ccr.