From previous studies on hydronephrotic rats in our laboratory, an increased sensitivity of the tubuloglomerular feedback (TGF) mechanism was found during extracellular volume expansion (VE). In contrast, the mechanism resets to a lower sensitivity during VE in control animals. The resetting in hydronephrotic rats was reversed by blocking the thromboxane (Tx) system. The present study was performed to measure changes in pelvic pressure (Pp
) in hydronephrotic kidneys during VE, and the effect of Tx inhibition on those changes. In addition, TGF was characterized during VE of hydronephrotic rats while Pp
was kept at the pre-VE level. On VE, Pp
increased moderately from a control value of 2.9 mm Hg to a plateau with a mean value of 6.0 mm Hg (control, 0.7 vs. 2.1 mm Hg). After Tx inhibition, Pp
was increased by more than 100%, with a plateau value of 13.6 mm Hg. When Pp
was normalized and fixed, the direction of resetting of TGF was normal. The results from this study indicate that the resetting of TGF is of importance to keep glomerular filtration rate low and reduce Pp
in the hydronephrotic kidney. Tx and Pp
are involved in the resetting of TGF.
Dr. Peter Morsing, Department of Physiology, and Biophysics, Sölvegatan 19, S-233 62 Lund (Sweden)
Accepted: July 25, 1989
Published online: November 07, 2008
Number of Print Pages : 9
Kidney and Blood Pressure Research
Vol. 13, No. 4, Year 1990 (Cover Date: 1990)
Journal Editor: Wanner C. (Würzburg)
ISSN: 1420–4096 (Print), eISSN: 1423–0143 (Online)
For additional information: http://www.karger.com/KBR
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