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Angiotensin-mediated alterations in nephron function in Goldblatt hypertensive rats
The American Journal of Physiology
|December 1, 1982
Summary
Angiotensin I converting enzyme inhibitor (CEI) treatment improved superficial nephron function in Goldblatt hypertensive rats. CEI reduced blood pressure while increasing filtration and excretion, indicating reduced tubular reabsorption.
Area of Science:
- Nephrology
- Cardiovascular Physiology
- Pharmacology
Background:
- Goldblatt hypertension involves renal artery stenosis, leading to elevated blood pressure and altered kidney function.
- Angiotensin II plays a critical role in regulating blood pressure and kidney hemodynamics.
- Superficial nephron function is crucial for maintaining overall kidney homeostasis.
Purpose of the Study:
- To investigate the effects of angiotensin I converting enzyme inhibitor (CEI) on superficial nephron function in a two-kidney, one-clip Goldblatt hypertensive (GH) rat model.
- To determine the role of angiotensin II in mediating tubular reabsorption in the nonclipped kidney during hypertension.
Main Methods:
- Administration of CEI (SQ 20,881) to GH rats.
- Collection of fluid from late proximal and early distal tubules before and during CEI administration.
- Measurement of glomerular filtration rate (GFR), urine flow, sodium excretion, and single nephron GFR (SNGFR).
- Analysis of tubular fluid reabsorption and pressures within nephron segments and peritubular capillaries.
Main Results:
- CEI treatment significantly increased GFR, urine flow, sodium excretion, and SNGFR despite a reduction in arterial blood pressure.
- Absolute and fractional reabsorption of fluid, chloride, and solute decreased in the proximal tubule.
- Absolute reabsorption increased, while fractional reabsorption decreased in the segment between proximal and distal tubules.
- Fractional reabsorption decreased significantly at the distal tubule level.
- Proximal and distal tubule hydrostatic pressures increased, while peritubular capillary pressure decreased.
Conclusions:
- Inhibition of angiotensin II formation with CEI enhances superficial nephron filtration and reduces tubular reabsorption in the nonclipped kidney of GH rats.
- These findings suggest an angiotensin II-mediated enhancement of tubular reabsorption in the nonclipped kidney during Goldblatt hypertension.
- CEI represents a potential therapeutic strategy for managing hypertension by improving renal hemodynamics and function.