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Hyperuricemia exacerbates chronic cyclosporine nephropathy
1Division of Nephrology, University of Washington Medical Center, Seattle 98185, USA.
Transplantation
|May 15, 2001
Summary
Elevated uric acid levels worsen cyclosporine (CSA) induced kidney damage in rats. This exacerbation is linked to the renin-angiotensin system and reduced nitric oxide, not crystal formation.
Area of Science:
- Nephrology
- Pharmacology
- Toxicology
Background:
- Hyperuricemia is a common complication of cyclosporine (CSA) treatment.
- Chronic hyperuricemia is linked to tubulointerstitial disease and vasoconstriction, suggesting a role in CSA nephropathy.
Purpose of the Study:
- To investigate the hypothesis that hyperuricemia contributes to chronic cyclosporine nephropathy.
- To determine the effect of elevated uric acid on CSA-induced kidney injury in a rat model.
Main Methods:
- Cyclosporine nephropathy was induced in rats using CSA (15 mg/kg/day) for 5-7 weeks.
- Hyperuricemia was induced by co-administering oxonic acid with CSA.
- Histological and functional assessments were performed, with control groups receiving vehicle or oxonic acid alone.
Main Results:
- CSA treatment led to mild hyperuricemia, arteriolar hyalinosis, tubular injury, and interstitial fibrosis.
- Co-administration of oxonic acid with CSA (CSA-OA) resulted in higher uric acid levels and more severe kidney damage.
- Both CSA and CSA-OA groups showed increased renal renin and decreased nitric oxide synthases (NOS1 and NOS3), with more pronounced changes in the CSA-OA group. Intrarenal urate crystals were absent.
Conclusions:
- Increased uric acid exacerbates cyclosporine-induced nephropathy in rats.
- The mechanism involves activation of the renin-angiotensin system and inhibition of intrarenal nitric oxide production.
- Intrarenal urate crystal deposition is not the mechanism by which hyperuricemia worsens CSA nephropathy.