Renal adaptation to additional nephrons: a functional study in the three-kidney rat

Renal functional adaptation to additional nephrons was studied in rats in which a third kidney was transplanted isogeneically. Total renal function did not increase when an extra kidney was added. Quantitation of the contribution of each kidney, by means of a 99mTc-DTPA scan, showed that the glomerular filtration rate of the native kidneys had decreased to counterbalance the added function. The glomerular filtration rate of the transplanted kidneys as well as its number of glomeruli were 20% less than that of the intact native kidneys. The present findings once again illustrate the kidney's remarkable capacity for functional adaptation to a change in the total number of nephrons.