Abstract
This study compared the renal metabolism of arachidonic acid in Brattleboro (BB) (vasopressin deficient) and Long-Evans (LE) control rats and the effects of a cytochrome P-450 (CYP) inhibitor 1-aminobenzotriazole (ABT) on renal function in these animals. The production of 20-hydroxyeicosatetraenoic acid (20-HETE) by renal cortical and outer medullary microsomes was significantly greater in BB than in LE rats (155 ± 16 vs. 92 ± 13 and 59 ± 7 vs. 33 ± 3 pmol·min-1·mg protein -1). Renal cortical epoxygenase activity was not different in these strains. The expression of CYP4A proteins was 58 and 78% higher in the renal cortex and outer medulla of BB than in LE rats. Chronic treatment of BB rats with a vasopressin type 2 receptor agonist for 1 wk normalized the renal production of 20-HETE. Chronic blockade of the formation of 20-HETE and EETs with ABT had little effect on renal function in LE rats. However, urine flow increased by 54% and urine osmolarity decreased by 33% in BB rats treated with ABT. Plasma levels of oxytocin fell significantly from 7.2 ± 1.3 to 3.9 ± 1.0 pg/ml. The effects of ABT in BB rats were attenuated by chronic infusion of oxytocin (0.7 ng·min-1·100 g-1) to maintain fixed high plasma levels of this hormone. These results indicate that the expression of CYP4A protein and the renal formation of 20-HETE are elevated in the kidney of BB rats due to a lack of vasopressin and that chronic blockade of the formation of 20-HETE and EETs with ABT promotes water excretion in vasopressin-deficient BB rats by reducing the circulating levels of oxytocin, which is a weak vasopressin agonist.
Original language | English |
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Pages (from-to) | F1333-F1340 |
Journal | American Journal of Physiology - Renal Physiology |
Volume | 289 |
Issue number | 6 58-6 |
DOIs | |
Publication status | Published - 2005 Dec |
Keywords
- 20-hydroxyeicosatetraenoic acid
- Brattleboro rats
- Cytochrome P-450
- Epoxyeicosatrienoic acid
- Renal hemodynamics
ASJC Scopus subject areas
- Physiology
- Urology