dinoprost and Renal-Insufficiency

Hyperuricemia may play a role in the pathogenesis of cardiovascular disease, but uric acid is also a significant antioxidant. We investigated the effects of oxonic acid-induced hyperuricemia on carotid artery tone in experimental renal insufficiency.. Three weeks after 5/6 nephrectomy (NX) or Sham operation, male Sprague-Dawley rats were allocated to 2.0% oxonic acid or control diet for 9 weeks. Blood pressure was monitored using tail cuff, isolated arterial rings were examined using myographs, and blood and urine samples were taken, as appropriate. Oxidative stress and antioxidant status were evaluated by measuring urinary 8-isoprostaglandin F(2 alpha) (8-iso-PGF(2 alpha)) excretion and plasma total peroxyl radical-trapping capacity (TRAP), respectively.. Plasma creatinine was elevated twofold in NX rats, but neither NX nor oxonic acid diet influenced blood pressure. Urinary 8-iso-PGF(2 alpha) excretion was increased over 2.5-fold in NX rats on control diet. Oxonic acid diet increased plasma uric acid 2-3-fold, TRAP 1.5-fold, and reduced urinary 8-iso-PGF(2 alpha) excretion by 60-90%. Carotid vasorelaxation to acetylcholine in vitro, which could be abolished by nitric oxide (NO) synthase inhibition, was reduced following NX, whereas maximal response to acetylcholine was augmented in hyperuricemic NX rats. Vasorelaxation to nitroprusside was impaired in NX rats, whereas oxonic acid diet increased sensitivity also to nitroprusside in NX rats.. Oxonic acid-induced hyperuricemia reduced oxidative stress in vivo, as evaluated using urinary 8-iso-PGF(2 alpha) excretion, increased plasma TRAP, and improved NO-mediated vasorelaxation in the carotid artery in experimental renal insufficiency.

Topics: Animals; Carotid Arteries; Creatinine; Dinoprost; Hyperuricemia; Male; Nephrectomy; NG-Nitroarginine Methyl Ester; Oxidative Stress; Oxonic Acid; Peroxides; Rats; Rats, Sprague-Dawley; Renal Insufficiency; Uric Acid; Vasodilation

The renin angiotensin system has been shown to be involved in the pathogenesis of vascular and renal sequelae of diabetes mellitus. In type 2 diabetes mellitus, angiotensin receptor blockers have been shown to exert clinical benefit by reducing the progression of diabetic nephropathy. They also improve endothelium-mediated vascular function. The latter effect is partly due to the reduction of angiotensin II-associated oxidative stress. Moreover, small clinical studies have shown that treatment with angiotensin receptor blockers also reduces the circulating levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase. In the VIVALDI trial, the ability of the angiotensin receptor blocker telmisartan to reduce the progression of diabetic nephropathy (associated with proteinuria) in comparison with valsartan in more than 800 patients with type 2 diabetes during 1 year of treatment is being studied. In order to gain more detailed insight into the potential pathomechanisms associated with this effect, further end-points have been defined. Among these are the circulating levels of ADMA and the urinary excretion rate of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha). The former is an endogenous inhibitor of NO-mediated vascular function(s) and a prospectively determined marker of major cardiovascular events and mortality; the latter is a lipid peroxidation product resulting from the nonenzymatic peroxidation of arachidonic acid, which exerts detrimental vascular effects similar to those of thromboxane A2. Urinary 8-iso-PGF2alpha has been shown in clinical studies to be an independent marker of cardiovascular disease. Highlighting the effects of telmisartan on ADMA and 8-iso-PGF levels in such a large cohort of diabetic patients will enhance our understanding of the roles of dysfunctional NO metabolism and redox mechanisms in the pathogenesis of end-organ damage and its prevention by pharmacotherapy with angiotensin receptor blockers.

Topics: Adult; Aged; Aged, 80 and over; Angiotensin II Type 1 Receptor Blockers; Antihypertensive Agents; Arginine; Benzimidazoles; Benzoates; Clinical Protocols; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Dinoprost; Endothelium, Vascular; Humans; Hypertension; Middle Aged; Multicenter Studies as Topic; Oxidative Stress; Randomized Controlled Trials as Topic; Renal Insufficiency; Telmisartan; Tetrazoles; Valine; Valsartan

Muscle injury (rhabdomyolysis) and subsequent deposition of myoglobin in the kidney causes renal vasoconstriction and renal failure. We tested the hypothesis that myoglobin induces oxidant injury to the kidney and the formation of F2-isoprostanes, potent renal vasoconstrictors formed during lipid peroxidation. In low density lipoprotein (LDL), myoglobin induced a 30-fold increase in the formation of F2-isoprostanes by a mechanism involving redox cycling between ferric and ferryl forms of myoglobin. In an animal model of rhabdomyolysis, urinary excretion of F2-isoprostanes increased by 7.3-fold compared with controls. Administration of alkali, a treatment for rhabdomyolysis, improved renal function and significantly reduced the urinary excretion of F2-isoprostanes by approximately 80%. EPR and UV spectroscopy demonstrated that myoglobin was deposited in the kidneys as the redox competent ferric myoglobin and that it's concentration was not decreased by alkalinization. Kinetic studies demonstrated that the reactivity of ferryl myoglobin, which is responsible for inducing lipid peroxidation, is markedly attenuated at alkaline pH. This was further supported by demonstrating that myoglobin-induced oxidation of LDL was inhibited at alkaline pH. These data strongly support a causative role for oxidative injury in the renal failure of rhabdomyolysis and suggest that the protective effect of alkalinization may be attributed to inhibition of myoglobin-induced lipid peroxidation.

Topics: Animals; Bicarbonates; Dinoprost; Disease Models, Animal; Electron Spin Resonance Spectroscopy; Glycerol; Humans; Hydrogen-Ion Concentration; Kidney; Lipoproteins, LDL; Metmyoglobin; Myoglobin; Oxidation-Reduction; Potassium Compounds; Rats; Renal Insufficiency; Rhabdomyolysis; Spectrophotometry; Vasoconstriction