AJP - Renal Physiology, Vol 244, Issue 6 650-F658, Copyright © 1983 by American Physiological Society
Glomerular ultrafiltration dynamics during increased renal venous pressure
J. R. Dilley, A. Corradi and W. J. Arendshorst
The effects of unilateral partial renal venous ligation on whole kidney and
single nephron function were determined in anesthetized euvolemic
Munich-Wistar rats using clearance, blood flow, and micropuncture
techniques. Increased venous pressure (4-22 mmHg) reduced glomerular
filtration rate (GFR) and renal plasma flow (RPF) to 60% of control values;
filtration fraction (FF) was constant. Similar responses occurred in the
superficial cortex, as evidenced by a 40% fall in SNGFR determined while
intratubular pressure was maintained at the elevated precollection level.
Fractional reabsorption by the proximal convoluted tubule remained
constant, indicating maintenance of glomerulotubular balance. The
contralateral kidney exhibit a diuresis and natriuresis while GFR and RPF
were stable. In the experimental kidney single nephron glomerular plasma
flow decreased by 35% due to increments in preglomerular and efferent
arteriolar resistance. The transcapillary hydrostatic pressure gradient was
unchanged since there were similar 7- to 8-mmHg increases in glomerular
capillary and Bowman's space pressures. Filtration pressure disequilibrium
was observed in control and experimental periods. Mean effective
ultrafiltration pressure was similar in both periods. Specific values for
the ultrafiltration coefficient (Kf) fell from 0.023 to 0.015 nl . s-1.
mmHg-1. Accordingly, partial renal venous ligation produces ipsilateral
vasoconstriction and a fall in GFR that is primarily due to a proportional
decline in Kf.
