[The effect of a low-protein diet on the epithelium of nephron segments in sheep]

Changes in the epithelium thickness of proximal and distal convoluted tubule of cortex, thin descending limb of Henle loop from inner stripe of outer medulla, thick ascending limb from outer stripe of outer medulla and of collecting duct from inner medulla were investigated in young growing sheep fed a low protein diet (LP). Sheep on LP-diet were given a daily ration with 5.73 g of nitrogen and 6.13 MJ of digestible energy (DE) while the daily intake of control group was 19.51 g of N and 12.29 MJ of DE. Both groups of animals were fed these diets at least 6 weeks before collection of kidneys. Morphometric analysis with digitizing tablet showed that intake of LP-diet resulted in significant reduction of epithelium thickness in both distal convoluted tubule and thick ascending limb while the epithelium of collecting duct was found to be thicker. No changes of the epithelium dimensions were determined in proximal tubule and in thin descending limb of Henle loop. Presented results point to the morphological expression of the adaptation of sheep kidneys to a low dietary protein intake which is associated with the increased renal reabsorption of urea.