Rat Glomerular Glycoprotein Composition and Metabolism in Aminonucleoside Nephrosis 1

Summary

In aminonucleoside nephrotic rats, the sialic acid concentration of glomerular membrane fractions were significantly less than values obtained from control preparations. No differences were detected in the concentrations of glucose, galactose, mannose, or hexosamine. The administration of ¹⁴C-glucosamine as precursor of sialic acid, 2 days after giving aminonucleoside, was followed by a significantly greater increase in specific activity of glomerular sialic acid over the subsequent 1-8 days; the falloff in specific activity from days 6 to 13 had a half-life of 4 days compared with 20 days in control animals. The specific activity of sialic acid in glomerular basement and cellular membrane fractions 24 hr after administration of ¹⁴C-glucosamine was 2-5 times greater in animals given aminonucleoside than in control rats. This increase in synthesis may be a consequence of increased degradation or turnover of glomerular membrane sialoprotein.