AJP - Renal Physiology, Vol 248, Issue 5 688-F697, Copyright © 1985 by American Physiological Society
Tubuloglomerular feedback after nephron or ureteral obstruction
G. A. Tanner
The effects of 1 day of single nephron, unilateral ureteral (UUO), and
bilateral ureteral (BUO) obstruction on tubuloglomerular feedback were
studied in anesthetized rats. Stop-flow pressure (SFP) was measured as an
index of glomerular capillary pressure before, during, and after loop of
Henle microperfusion. Tubuloglomerular feedback (delta SFP) showed an
increased sensitivity to low loop perfusion rates and an increased maximal
response after 1 day of single nephron obstruction or relief of UUO.
Tubuloglomerular feedback was not significantly different from normal after
release of BUO. Whole kidney glomerular filtration rate (GFR) was about 10%
of normal after release of ureteral obstruction, and single nephron
glomerular filtration rate (SNGFR) averaged one-third of normal. Paired
measurements of SNGFR from proximal and distal tubules revealed no
significant differences in control or in BUO kidneys, but a significant
proximal-distal SNGFR difference was observed after UUO. The results
suggest that tubuloglomerular feedback does not significantly contribute to
the low GFR after release of BUO; after release of UUO, approximately
one-fourth of the fall in GFR may be due to activation of the feedback
mechanism.
