Degradation of glomerular basement membrane in diabetes. II. Proteolytic activity of diabetic and nondiabetic glomeruli.
The proteolytic effects of isolated glomeruli of diabetic rats on glomerular basement membrane of nondiabetic rats was investigated at various times after streptozotocin injection. One week after induction of diabetes, proteolytic activity remained unchanged as compared with nondiabetic controls. However, 4 and 10 weeks after streptozotocin injection, glomerular degradation of collagenous (but not noncollagenous) peptides of basement membranes increased (+24% as compared with control experiments). Using diabetic basement membrane as substrate, degradation of collagenous and noncollagenous peptides caused by diabetic glomeruli was 2.6-fold and 1.7-fold higher than in control experiments with nondiabetic glomeruli. The results indicate that the disturbed degradation of glomerular basement membrane in diabetes is not due to a decreased activity of glomerular proteolytic enzymes. In contrast, it can be concluded that the increased resistance of diabetic basement membrane to proteolytic degradation could be partially compensated by quantitative and qualitative changes of the proteolytic potential of diabetic glomeruli.
Leber
R
R
Medizinische Universitätsklinik, Heidelberg, Federal Republic of Germany.
Knecht
R
R
Hasslacher
C
C
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001485:Basement Membrane / Q000378:metabolism*; D002352:Carrier Proteins; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D007678:Kidney Glomerulus / Q000201:enzymology*; D008297:Male; D010447:Peptide Hydrolases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors
D000596:Amino Acids; D002352:Carrier Proteins; D011506:Proteins; C007105:c1q-binding proteins; D010447:Peptide Hydrolases