Glycosaminoglycans (macromolecular sugars) of the rat renal papilla: ultrastructural and cytochemical findings.

Sulfated glycosaminoglycans have been stained at the ultrastructural level in interstitial matrix of the rat renal papilla, using colloidal thorium dioxide at low pH. Concentration of these proteoglycans was maintained during diuresis, and was thought to be greatly diminished during antidiuresis. The possible relation of these findings to the kidney's mechanism for urine concentration and dilution is discussed.