Compensatory hypertrophy of single nephrons following ischemic injury in the rat

In Sprague-Dawley rats, the increase in single nephron glomerular filtration rate (SNGFR) following uninephrectomy is due to an increase in glomerular plasma flow (GPF) along with an increase in the glomerular capillary ultrafiltration coefficient (Kf). Hypertrophy of individual nephrons also occurs when renal mass is reduced by disease or ischemic injury. To characterize the factors determining SNGFR in the minority of nephrons that recover from a severe ischemic insult, rats were studied 4 weeks after 1 hour of complete unilateral renal artery occlusion and the results compared to those obtained in normal rats. Indirect determination of the dynamics of glomerular ultrafiltration along with microangiographic studies indicated that despite a reduction in total renal blood flow in the postischemic kidney, a minority of nephrons were hyperperfused. The increase of GPF in these nephrons along with a significant increase in Kf was responsible for the observed increase in SNGFR.