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THE ROLE OF THE KIDNEY IN NITROGEN CONSERVATION IN SHEEP
Author(s) -
McIntyre KH,
Williams VJ
Publication year - 1970
Publication title -
australian journal of experimental biology and medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0004-945X
DOI - 10.1038/icb.1970.8
Subject(s) - urea , urine flow rate , reabsorption , chemistry , urine , medicine , renal function , kidney , endocrinology , excretion , zoology , biochemistry , biology
Summary The experiment was designed to test the theory that there is a special renal mechanism involved in urea conservation in sheep given diets low in protein content. The effects of different plasma urea levels and urine flow rates on renal function with respect to urea reabsorption were studied, using three rations which varied in protein content. The same rations were also studied in conjunction with an intravenous infusion of urea of 12 g. per 8 hours. The urea clearances and clearance ratios varied with the dietary treatments imposed and were lowest on the diet which produced a minimum plasma urea level. The ratio of urea in urine to urea in plasma was inversely and linearly related to urine flow rate. The rates of excretion of urea in urine were linearly related to plasma urea nitrogen concentrations (P < 0·01) and urine flow rates (P < 0·01), while plasma urea nitrogen concentrations were linearly related to urine flow rates (P < 0·05). Urine flow rates were linearly related to urea clearances (P < 0·01) and clearance ratios (P < 0·01). The evidence presented suggests that urea reabsorption by the kidney is related to the amount of urea filtered by the kidney, which depends on the plasma urea nitrogen concentration. The ability of the sheep on the low protein diets fed in these experiments to conserve urea was apparently linked with the presentation of relatively small amounts of urea to the glomerulus. There was no evidence of a special renal mechanism.