Compensatory renal hypertrophy in Sprague-Dawley rats: glomerular ultrafiltration dynamics.

The factors responsible for the increase in glomerular filtration rate associated with compensatory hypertrophy in Sprague-Dawley rats were studied 2 weeks following uninephrectomy. In sham-operated rats, the single nephron glomerular filtration rate (SNGFR) was 40 nl/min and the calculated glomerular plasma flow (GPF) was 138 nl/min. Proximal intratubular free-flow (PT) and stop-flow (PSF) hydrostatic pressures were 12 and 34 mm/Hg, respectively. The estimated glomerular capillary hydrostatic pressure (PGC) was 49 mm Hg and the estimated efferent effective ultrafiltration pressure (PUFEA) was 12 mm Hg, indicatng filtration pressure disequilibrium. The specific ultrafiltration coefficient was calculated to be 0.039 nl/s . mm Hg per glomerulus. In uninephrectomized rats, SNGFR increased to 61 nl/min and the calculated GPF increased to 266 nl/min. PT was 12 mm Hg; PGCe was 49 mm Hg and PUFEA was 15 mm Hg. Kf was calculated to be 0.053 nl/s . mm Hg per glomerulus. These data indicate that in Sprague-Dawley rats under conditions of filtration pressure disequilibrium, the increase in GFR associated with compensatory hypertrophy is in part related to a significant change in Kf.