title: [Renal retention of urea in sheep].
abstract: The urea-retaining ability of kidneys of ruminants and returning it back to the blood circulation are important features of the mechanism of nitrogen conservation in the organism. Applying the model of a low-nitrogen diet to sheep we found out the low fractional excretion of urea (FE urea) as a result of increased urea transport capacity in renal tubules. The decrease in the amount of excreted urea by 85% was also accompanied by a reduced glomerular filtration rate (GFR). We tried to verify our hypothesis by the cross-perfusion method that the renal excretion of urea in sheep is regulated by a factor circulating in the blood. We found out that FE urea decreased significantly in the cross-perfused kidney (in sheep on a high-nitrogen diet, connected to sheep on a low-nitrogen diet), without any changes in GFR. Our hypothesis is well-supported by the above result. The kidneys of sheep on low nitrogen diet retain urea through a decrease in the GFR and increased tubular urea transport.
mesh_terms: D000818:Animals; D004032:Diet; D005919:Glomerular Filtration Rate; D007668:Kidney / Q000378:metabolism*; D009584:Nitrogen / Q000008:administration & dosage; D012756:Sheep / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*
chemical_list: D014508:Urea; D009584:Nitrogen
vernacular_title: Renálna retencia mocoviny u oviec.