Unilateral obstructive nephropathy in the rabbit. I. Early morphologic, physiologic, and histochemical changes

Complete unilateral obstruction was studied in adult male New Zealand rabbits in an attempt to relate the functional, morphologic, and histochemical changes. Glomerular filtration rate (GFR), concentrating ability, glucose reabsorption, osmolar clearance, and free water reabsorption were determined for the obstructed and contralateral kidney at intervals up to 32 days. T(m) glucose fell from a mean control value of 48 mg per minute after 1 day of obstruction and was reduced to less than 10 mg per minute by the 4th day. This was shown to be largely due to depression of GFR since there was no significant change in glucose reabsorption when this was factored for GFR. Ultrastructural and histochemical findings revealed a small fraction of nephrons with normal morphology. The concentrating ability of the obstructed kidney was severely altered by 1 day and this was related to the depression in GFR, alteration in the ultrastructure of the ascending thick limbs, widening of the interstitial space, the presence of microthrombi in some vasa recta, and progressive necrosis of the papillary tip. Fourteen enzymes were studied histochemically and their activity was related to the ultrastructural and functional changes observed.