الفهرس 
Uric Acid
Renin-angiotensin systemOnly 14 pages are availabe for public view
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Abstract
The present study was planned in order to assess effect of preexisting hyperuricemia, regarding its pro oxidant or its antioxidant effect, in aggravating or ameliorating the outcome from the later on exposure to renal ischemia reperfusion injury.
This work was performed on adult male Wistar rats, divided into 4 groups:
group I: Sham control rats.
group II: Hyperurecemic rats. Hyperurecemia was induced subcutaneous injection of Oxonic acid (2%) in a dose of 100 mg /Kg/day for 6 days for two weeks.
group III: Renal Ischemic- reperfused rats (renal I/R).
group IV: 2 weeks hyperuricemia followed by 24 hours renal I/R.
All groups including sham control group were injected with the vehicle in which oxonic acid was dissolved (Distilled water). Also, sham control group and group II, were subjected for exposure of the renal pedicles in both side, but they were not subjected to any renal I/R.
Body weight and kidney weight were measured, also blood pressure was measured.
Blood samples were collected for biochemical estimations of:
1. Plasma Urea, creatinine and Uric acid level.
2. Plasma electrolyte level: Na+ and k+.
3. Pro-oxidant parameters: plasma and renal tissue Malondialdhyde (MDA).
4. Anti-oxidant parameters: plasma total anti-oxidant capacity.
5. Plasma and renal tissue levels of NO.
The present study revealed that:
In oxonic acid treated rats (group II) There were significant increase in plasma level of uric acid and plasma total antioxidant capacity compared to control rats .Also there were significant increase in renal tissue MDA,plasma nitrite level compared to control rats and a higher though statistically non- significant in renal tissue nitrite compared to control rats. On the other hand there were non significant changes in plasma MDA level and blood pressure as well as no changes in plasma levels of potassium and sodium.
In ischemia reperfusion rats (group III) significant increase in plasma level of urea, creatinine , plasma and renal tissue levels of MDA were observed compared to control rats. Plasma level of total antioxidant capacity was decreased significantly compared to both control rats and oxonic treated group. There was a significant decrease in renal tissue nitrite compared to both controls and hyperuricemic group but no significant change in plasma nitrite. Although there were significant hyponatremia compared to control rats there were no changes in plasma levels of potassium.also blood pressure values showed no significant changes compared to its corresponding values in control rats.
In ischemia reperfusion preceded by hyperuricemia in (group IV) significant increase in plasma level of urea and creatinine compared to control rats were observed but compared to ischemia reperfusion only in group III creatinine level was decreased significantly. Total anti-oxidant level was significantly increased in comparison to group III with only ischemia reperfusion. Hyperuricemia plus ischemia reperfusion in this group exhibited significant decrease in renal tissue level of MDA in comparison to ischemia reperfusion only and also compared to oxonic treated group II with no change in plasma level of MDA. On the other hand there was an increased nitrite in renal tissue level compared to group III with only ischemia reperfusion. Blood pressure, sodium and potassium levels in group IV. All were non significantly changed compared to group III.
Conclusion
Mild hyperuricemia may provide a state of pharmacological ischemic preconditioning ameliorating the deleterious effects due to renal ischemia reperfusion injury. The increased nitric oxide in plasma and renal tissue with hyperuricemia may be the humoral mediator implemented in the supposed preconditioning effect.
In case of mild hyperuricemia and / or cases of oxidative stress the antioxidant effect of uric acid overwhelmed its pro-oxidant effect.
Mild hyperuricemia as a model may be used to estimate their suggested preconditioning effect in case of cardiac I/R injury.
Recommendations
Treatment of hyperuricemia should be restricted to cases of high level of uric acid.
Comparative studies in the presence of higher levels and longer duration may be in need to be examined.