Functional changes in compensatory hypertrophy of the canine kidney after uninephrectomy

Kidney weight and renal functional parameters were investigated in dogs 7 to 68 days after uninephrectomy. Average enlargement of the remaining kidney amounted to 35.1%. Renal blood flow (RBF) and glomerular filtration rate (GFR) calculated per 100 g actual kidney weight were identical in the non-hypertrophied controls and in the hypertrophied kidneys, i.e. structural and functional changes were strictly proportional. Calculation of mean nephron parameters (MNRBF and MNGFR) revealed an increase of about 43% in the hypertrophied kidneys, with an appropriate decrease in nephronal vascular resistance. The hypertrophied kidney showed an enhanced responsiveness to mannitol; increased MNRBF under stop flow conditions was due to a pronounced dilatation of the postglomerular vessels. There was no difference between control and hypertrophied kidneys in cortical zonal blood flow, as investigated by the labelled microsphere technique. Increase in parallel-connected cortical resistances towards the inner (juxtamedullary) zones was pronounced.