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A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction
Published on: December 20, 2014
A micropuncture study of postobstructive diuresis in the rat
The Journal of Clinical Investigation
|March 1, 1972
Summary
Postobstructive diuresis in rats is characterized by significant water and sodium excretion after relieving bilateral ureteral obstruction. Impaired reabsorption in distal tubules, not proximal, causes this diuresis, linked to elevated intrarenal pressure.
Area of Science:
- Nephrology
- Renal Physiology
- Urology
Background:
- Postobstructive diuresis is a complex renal response following urinary tract obstruction.
- Understanding the mechanisms of postobstructive diuresis is crucial for managing patients with obstructive uropathy.
Purpose of the Study:
- To investigate the syndrome of postobstructive diuresis in rats.
- To determine the specific sites of impaired tubular reabsorption responsible for postobstructive diuresis.
- To explore the role of intrarenal pressure in postobstructive diuresis.
Main Methods:
- Clearance and micropuncture studies were performed on rats after 24 hours of bilateral (BUL) or unilateral (UUL) ureteral ligation.
- Measurements included whole kidney and superficial nephron clearances of inulin and p-aminohippuric acid (PAH).
- Absolute and fractional water reabsorption was assessed along the nephron, with tubular fluid to plasma inulin ratios (TF/P(In)) analyzed.
Main Results:
- Rats with BUL exhibited significant diuresis and natriuresis upon relief, unaffected by vasopressin or d-aldosterone.
- Whole kidney and superficial nephron clearances of inulin and PAH were reduced in BUL rats, suggesting impaired deep nephron function.
- Impaired sodium reabsorption occurred primarily in the distal tubules, indicated by decreased TF/P(In) ratios, while proximal tubule reabsorption remained normal.
- Elevated prerelease intrarenal hydrostatic pressure (30.1 mm Hg) in BUL rats, compared to normal or below-normal in UUL rats (9.2 mm Hg), was observed.
Conclusions:
- Postobstructive diuresis following bilateral ureteral obstruction is characterized by impaired distal tubular sodium reabsorption.
- Heterogeneity in nephron function, with deep nephrons functioning poorly, contributes to the observed diuresis.
- Elevated intrarenal hydrostatic pressure during obstruction may be a key factor causing postobstructive diuresis.
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