The Functional Adaptation of the Diseased Kidney. I. Glomerular Filtration Rate*

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Abstract
These experiments were designed to investigate the capacity of the residual nephrons of the experimentally diseased kidney of the dog to undergo an adaptive increase in glomerular filtration. Glomerular filtration rate (GFR) was measured in both kidneys of 26 dogs with unilateral renal disease. Thereafter, the uninvolved contralateral kidney either was removed (21 dogs) or its ureter ligated (5 dogs). GFR increased in the diseased kidneys in 25 of the 26 animals; the average increment for the group was 60.6%. Renal plasma flow was measured in 14 of these animals, and the average increment in this function was 66.5%. The mechanisms underlying the adaptive increase in filtration rate are poorly understood; however, the influence of this adaptation on the functional characteristics of the nephron are striking. Hyperfiltration of the degree noted in these studies must lead not only to an increase in excretory capacity but to an increase in active transport of a number of solutes including sodium. Supernormal rates of sodium transport under basal conditions in turn would necessitate an increase in basal energy production and utilization per nephron. If similar degrees of hyperfiltration occur in man with chronic renal disease, this adaptation could contribute importantly both to the functional capabilities and to certain of the functional limitations observed in the chronically diseased kidney.