Glomerular basement membrane collagen synthesis rates in normal and diabetic rats

Glomerular basement membrane (GBM) protein and collagen synthesis rates were studied in normal and streptozotocin diabetic rats, using L-(2,3,3H)-proline as a radioactive precursor. The incorporation of tritiated proline into GMB proline was regarded as a measure of total protein synthesis and the incorporation into hydroxyproline as indicative of collagen synthesis. Total GBM protein and collagen synthesis rates were calculated from the simultaneous measurements of specific activities in the precursor (tissue-free) and protein-bound (GBM proline and hydroxyproline) pools. The results suggest that diabetic rats synthesized GBM protein and collagen at the rate of 1.90 and 0.61% per h, respectively, compared to 1.07 and 0.38% per h in normal rats. These data are consistent with our previous findings of increased GBM protein and collagen synthesis in streptozotocin diabetic rats.