3-nitrotyrosine and Hyperlipidemias

To investigate the relationship between insulin resistance, postprandial hyperglycemia, postprandial hyperlipidemia, and oxidative stress in type 2 diabetes, changes in postprandial glucose, triglyceride, and nitrotyrosine levels vs baseline after diet loading were examined in type 2 diabetic patients given pioglitazone (PG) or glibenclamide (GB). Twenty-four outpatients with type 2 diabetes treated with oral PG for 6 mo (BMI, 26.3 +/- 0.9; HbA1c, 8.2 +/- 0.2%) and 10 type 2 diabetic patients treated with GB (BMI, 27.4 +/- 1.6; HbA1c, 8.1 +/- 0.2%) at our institutions were compared. These patients were given meal tolerance tests (MTT; each consisting of energy 400 kcal, protein 8.7 g, fat 22.4 g, carbohydrate 41 g) before and 6 mo after administration of either agent. PG produced a significant decrease in FPG, HbA1c, HOMA-R, and TG levels in the subjects compared to baseline. In contrast, GB significantly decreased FPG and HbA1c levels, while not affecting HOMA-R and TG values. While PG produced a significant increase in LPL, HDL-cholesterol, and adiponectin levels, GB did not affect these values. At MTT 6 mo after PG administration, insulin levels before and 4 h after MTT, free fatty acid (FFA) levels 1, 2, and 4 h after MTT, glucose, TG, and RLP-TG levels before and 1, 2, 4, and 6 h after MTT were significantly decreased compared to baseline. At MTT 6 mo after GB administration, while a significant decrease in fasting and 2 h, postprandial glucose values compared to baseline MTT levels was observed, fasting and postprandial TG and RLP-TG levels remained unchanged compared to baseline. After 6 mo of PG and GB administration, serum nitrotyrosine levels before and after MTT were significantly decreased compared to baseline in both groups, while the decrease in nitrotyrosine levels before and after MTT was more marked in the subjects given PG. Our study results suggest that PG suppresses increases in postprandial glucose and TG levels, and improves insulin resistance; and, in addition, that PG may have a favorable impact on oxidative stress in type 2 diabetic patients.

Topics: Aged; Blood Glucose; Diabetes Mellitus, Type 2; Dose-Response Relationship, Drug; Fatty Acids, Nonesterified; Female; Glyburide; Glycated Hemoglobin; Humans; Hyperglycemia; Hyperlipidemias; Hypoglycemic Agents; Insulin; Insulin Resistance; Lipoprotein Lipase; Male; Middle Aged; Oxidative Stress; Pioglitazone; Postprandial Period; Thiazolidinediones; Time Factors; Triglycerides; Tyrosine

An advanced glycation end products (AGE)/a receptor for AGE (RAGE) axis plays a central role in the pathogenesis of diabetic vascular remodeling. This study was conducted to clarify the role of RAGE in nondiabetic atherosclerosis. We used the aortic and coronary atherosclerotic lesions of Watanabe heritable hyperlipidemic (WHHL) rabbits prone to myocardial infarction (WHHLMI) at 1 to 14 months. Immunohistochemistry demonstrated the significant expression of RAGE as early as at 1 month with the stronger expression at 3 and 7 months, which was remarkably diminished at 14 months. RAGE expression was concordant with AGE accumulation. The major original sources of RAGE expression were macrophages and smooth muscle cells in addition to endothelial cells, and RAGE expression was distributed in the areas of phospholipid products, a component of oxidized LDL and nitrotyrosine. The concentrations of serum AGE did not alter significantly with aging. These findings suggested the expression of RAGE was induced by hyperlipidemia and oxidative stress independent of diabetes in WHHLMI rabbits. Additionally, our in vitro study showed that silencing of RAGE tended to attenuate oxidized-LDL-triggered PAI-1 expression in human cultured macrophages, as well as oxidized-LDL-induced tissue factor expression in peritoneal macrophages, suggesting a possible role of RAGE in prothrombogenic molecular regulation. In conclusion, the present study provides in vivo evidence that RAGE plays an integral role in the initiation and progression of nondiabetic atherosclerosis, suggesting that RAGE may be a novel target for treating not only diabetic but also nondiabetic vascular complications.

Topics: Aging; Animals; Antigens, Neoplasm; Atherosclerosis; Disease Models, Animal; Female; Gene Knockdown Techniques; Glycation End Products, Advanced; Humans; Hyperlipidemias; Immunohistochemistry; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinases; Oxidative Stress; Plaque, Atherosclerotic; Rabbits; Receptor for Advanced Glycation End Products; Tyrosine

The aim of this study was to investigate the effect of high cholesterol (CHOL) and CHOL + methionine (MET) diets on atherogenic and oxidative index parameters and on the factors that influence nitric oxide (NO) bioavailability. Also, attempts were made to determine whether dietary betaine (BET) resulted in any improvement in the changes that occurred after CHOL + MET administration.. Guinea pigs were fed chow containing 1.5% CHOL with or without 2% MET for 10 wk. A third group received the CHOL + MET + BET diet. Control groups were given standard chow or standard chow + BET. Arginine, NO, nitrotyrosine (NT), and asymmetric dimethylarginine (ADMA) levels; lipid profile; and dimethylarginine dimethylaminohydrolase (DDAH) activity were measured. The liver and aorta were subjected to histopathologic analysis.. The CHOL + MET diet caused higher serum CHOL and homocysteine levels, but no further increases were seen in aortic CHOL and diene conjugate (DC) levels and histopathologic lesions as compared with the CHOL group. Hepatic lipids and DC levels were also higher, and histopathologic lesions were more severe. CHOL + MET feeding increased ADMA and NT levels as compared with those of the CHOL-fed group. When BET (1 g/kg body weight/d) was added to the CHOL + MET diet, homocysteine and lipid levels decreased and histopathologic changes were reversed. BET diet decreased serum ADMA and hepatic and aortic DC levels and partly restored DDAH activity.. BET supplementation may be effective in preventing hyperlipidemia, disturbed NO availability, oxidative stress, and the development of fatty liver and atherosclerotic lesions that might result from excess amounts of cholesterol and methionine in the diet.

Topics: Animals; Arginine; Atherosclerosis; Betaine; Cholesterol; Cholesterol, Dietary; Diet, High-Fat; Dietary Supplements; Fatty Liver; Guinea Pigs; Hyperlipidemias; Lipid Peroxidation; Liver; Male; Malondialdehyde; Methionine; Nitric Oxide; Tyrosine

The present study examined whether hemin could prevent the development of high-fat diet-induced insulin resistance in the liver and skeletal muscle using a hyperinsulinemic-euglycemic clamp. A four-week high-fat feeding to mice increased the body weight, fat mass, and plasma levels of insulin and lipid, which were reduced by hemin. High-fat diet reduced whole body glucose uptake, which were increased by hemin. Insulin-stimulated hepatic glucose production (HGP) was increased by high-fat diet, but hemin had no significant effect on HGP. Skeletal muscle glucose uptake was reduced by high-fat diet, and hemin normalized the glucose uptake. High-fat diet increased triglyceride levels and mRNA levels of lipogenic enzymes, and decreased mRNA levels of enzymes involved in lipid β-oxidation, which was reversed by hemin. Phosphorylated AMP-activated protein kinase levels were increased in the skeletal muscle of high fat-fed hemin-injected mice. High-fat diet reduced mRNA levels of antioxidant enzymes and increased mRNA levels of inflammatory cytokines and nitrotyrosine levels, which was normalized by hemin in the skeletal muscle. However, hemin had no significant effect on these factors in the liver. These results suggest that hemin prevents the development of high-fat diet-induced insulin resistance by increased insulin sensitivity in the skeletal muscle.

Topics: Adipose Tissue; AMP-Activated Protein Kinases; Animals; Body Weight; Cytokines; Depression, Chemical; Diet, High-Fat; Gene Expression; Glucose; Glucose Clamp Technique; Glutathione Peroxidase; Glutathione Peroxidase GPX1; Heme Oxygenase (Decyclizing); Hemin; Hyperinsulinism; Hyperlipidemias; Insulin Resistance; Liver; Male; Mice, Inbred C57BL; Muscle, Skeletal; Superoxide Dismutase; Triglycerides; Tyrosine

Cardioprotection by ischemic preconditioning (IP) was abolished in connexin 43 (Cx43)-deficient mice due to loss of Cx43 located in mitochondria rather than at the sarcolemma. IP is lost in hyperlipidemic rat hearts as well. Since changes in mitochondrial Cx43 in hyperlipidemia have not yet been analyzed, we determined total and mitochondrial Cx43 levels in male Wistar rats fed a laboratory chow enriched with 2% cholesterol or normal chow for 12 wk. Hearts were isolated and perfused according to Langendorff. After a 10-min perfusion, myocardial tissue cholesterol, superoxide, and nitrotyrosine contents were measured and Cx43 content in whole heart homogenate and a mitochondrial fraction determined. In the cholesterol-fed group, tissue cholesterol and superoxide formation was increased (P < 0.05), while total Cx43 content remained unchanged. Mitochondrial total and dephosphorylated Cx43 content decreased. Hearts were subjected to an IP protocol (3 × 5 min ischemia-reperfusion) or time-matched aerobic perfusion followed by 30-min global ischemia and 5-min reperfusion. IP reduced infarct size in normal but not in cholesterol-fed rats. At 5-min reperfusion following 30-min global ischemia, the total and dephosphorylated mitochondrial Cx43 content was increased, which was abolished by IP in both normal and high-cholesterol diet. In conclusion, loss of cardioprotection by IP in hyperlipidemia is associated with a redistribution of both sarcolemmal and mitochondrial Cx43.

Topics: Animals; Cholesterol; Cholesterol, Dietary; Connexin 43; Hyperlipidemias; Ischemic Preconditioning, Myocardial; Male; Mitochondria, Heart; Models, Animal; Myocardial Infarction; Rats; Rats, Wistar; Sarcolemma; Superoxides; Tyrosine

The aim of the present study was to investigate if hyperlipidemia interferes with the infarct size-limiting effect of postconditioning and to study the involvement of peroxynitrite in this phenomenon. Rats were fed a 2% cholesterol-enriched or normal diet for 12 wk. Infarct size by triphenyltetrazolium chloride staining was measured in hearts isolated from both groups and subjected to 30 min coronary occlusion followed by 120 min reperfusion with or without the postconditioning protocol induced by six cycles of 10 s coronary occlusion and 10 s reperfusion at the onset of the reperfusion. Postconditioning significantly decreased infarct size in the normolipidemic but not in the hyperlipidemic group. Postconditioning increased cardiac 3-nitrotyrosine concentration (a marker for peroxynitrite formation) in the normal but not in the cholesterol-fed group when measured at the 5th min of reperfusion. Next, we tested if the postconditioning-induced acute increase in peroxynitrite is involved in the cardioprotection in normolipidemic animals in separate experiments. Postconditioning failed to decrease infarct size in the presence of the peroxynitrite decomposition catalyst 5,10,15,20-tetrakis-[4-sulfonatophenyl]-porphyrinato-iron [III] (20 mg/l) in normolipidemic animals. We conclude that an early increase in peroxynitrite after postconditioning plays a role in cardioprotection. Furthermore, hyperlipidemia blocks the cardioprotective effect of postconditioning at least in part via deterioration of the postconditioning-induced early increase in peroxynitrite formation.

Topics: Animals; Biomarkers; Cholesterol, Dietary; Disease Models, Animal; Hyperlipidemias; Male; Metalloporphyrins; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Peroxynitrous Acid; Rats; Signal Transduction; Stress, Physiological; Tyrosine

We investigated whether aliskiren, a direct renin inhibitor, improves NO bioavailability and protects against spontaneous atherosclerotic changes. We also examined the effects of cotreatment with aliskiren and valsartan, an angiotensin II receptor blocker, on the above-mentioned outcomes. Watanabe heritable hyperlipidemic rabbits were treated with vehicle (control), aliskiren, valsartan, or aliskiren plus valsartan for 8 weeks. Then, acetylcholine-induced NO production was measured as a surrogate index of endothelium protective function, and both superoxide and vascular peroxynitrite were measured. Tetrahydrobiopterin in aortic segments was assessed by high-performance liquid chromatography with fluorescence detection. Plaque area was quantified by histology. Increase in plasma NO concentration in response to intra-aortic acetylcholine infusion was significantly greater in all of the test groups than in controls. Aliskiren+valsartan cotreatment increased acetylcholine-induced NO by 6.2 nmol/L, which was significantly higher than that with either aliskiren or valsartan alone. Vascular superoxide and peroxynitrite levels were both significantly higher in controls and significantly lower in the aliskiren+valsartan group than in the aliskiren or valsartan group. The highest tetrahydrobiopterin levels were observed after aliskiren+valsartan cotreatment. Histology of the thoracic aorta revealed that the plaque area was significantly decreased with combination therapy compared with monotherapy. Treatment with a direct renin inhibitor has protective effects on endothelial function and atherosclerotic changes. Furthermore, cotreatment with a direct renin inhibitor and an angiotensin II receptor blocker has additive protective effects on both.

Topics: Acetylcholine; Amides; Animals; Antihypertensive Agents; Atherosclerosis; Biopterins; Blood Pressure; Drug Therapy, Combination; Endothelium, Vascular; Fumarates; Heart Rate; HSP90 Heat-Shock Proteins; Hyperlipidemias; Inflammation Mediators; Lipids; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Oxidative Stress; Proto-Oncogene Proteins c-akt; Rabbits; Renin; Tetrazoles; Tyrosine; Valine; Valsartan; Vasodilation; Vasodilator Agents

We investigated the effects of co-administration of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor and angiotensin II type 1 receptor blocker (ARB) on nitric oxide (NO) bioavailability in genetically hyperlipidemic rabbits with our newly developed NO sensor. A total of 36 myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits equally derived (n=6 per group) were treated with 1) vehicle (control), 2) hydralazine (15 mg/kg/d), 3) the HMG-CoA reductase inhibitor pitavastatin (P: 0.5 mg/kg/d), 4) the ARB valsartan (V: 5 mg/kg/d), and 5) pitavastatin+valsartan (P+V) together without or 6) with N(G)-nitro-L-arginine methyl ester (L-NAME) for 8 weeks. After treatment, acetylcholine (ACh)-induced NO production was measured as a surrogate for endothelium protective function, and vascular peroxynitrite (a product of superoxide and NO) was measured for assessing dysfunctional endothelial NO synthase activity. Plaque area was quantified by histology as well as optical coherence tomography (OCT). Intra-aortic infusion of ACh produced an increase in plasma NO concentration, which was significantly greater with all drug treatments than with the control. P+V increased ACh-induced NO by 4.1 nmol/L significantly more than either P or V singly. The vascular peroxynitrite concentration was 1.6 pmol/mg protein in the control group and significantly less than those in the P- and V-monotherapy-groups. The lowest peroxynitrite concentration was observed in the P+V group (0.4 pmol/mg protein), which was significantly lower than those in the P- and the V-monotherapy-groups. OCT and histology of the thoracic aorta revealed that the plaque area decreased significantly more with the combination than with the monotherapy. In conclusion, the combined treatment with an HMG-CoA reductase inhibitor and an ARB may have additive protective effects on endothelial function as well as atherosclerotic change.

Topics: Acetylcholine; Angiotensin II Type 1 Receptor Blockers; Animals; Atherosclerosis; Biological Availability; Drug Therapy, Combination; Echocardiography; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hyperlipidemias; Myocardial Infarction; Nitric Oxide; Quinolines; Rabbits; Reactive Oxygen Species; Tetrazoles; Tyrosine; Valine; Valsartan

We investigated the effects of co-administration of an angiotensin-converting enzyme inhibitor (ACEI) and angiotensin type 1 receptor blocker (ARB) on nitric oxide (NO) bioavailability in genetically hyperlipidemic rabbits with our newly developed NO sensor. Plasma NO was measured using the new NO sensor in the abdominal aorta of anesthetized Watanabe heritable hyperlipidemic (WHHL) rabbits. Acetylcholine (ACh)-stimulated (20 microg in 5 min into the aortic arch) NO production was recorded after an 8 week per os pretreatment with 1) vehicle (control), 2) the ACEI enalapril (E: 3 mg/kg/day), 3) the ARB losartan (L: 30 mg/kg/day) and 4) enalapril (1.5 mg/kg/day)+losartan (15 mg/kg/day) (E+L). Intra-aortic infusion of ACh produced an increase in plasma NO concentration, which was significantly greater with all the drug treatments than with the control. E increased ACh-induced NO significantly more than L (by 6.9 nmol/L, and 4.7 nmol/L, respectively). E+L increased ACh-induced NO by 9.5 nmol/L, significantly more than either E or L. Plasma peroxynitrite concentration was 1.2 pmol/mg protein in the control group and significantly less than in the E- and L-group. The lowest peroxynitrite concentration was observed in the E+L group (0.5 pmol/mg protein), which was significantly lower than in the E-group and the L-group. Optical coherence tomography and histology of the thoracic aorta revealed that the plaque area decreased significantly more with the combination than with the monotherapy (p<0.01). In conclusion, the combined treatment with an ACEI and an ARB may have additive protective effects on endothelial function as well as atherosclerotic change.

Topics: Acetylcholine; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta, Abdominal; Atherosclerosis; Blood Pressure; Disease Models, Animal; Dose-Response Relationship, Drug; Enalapril; Heart Rate; Hyperlipidemias; Losartan; Male; Nitric Oxide; Peroxynitrous Acid; Rabbits; Tyrosine; Vasodilator Agents

Hyperlipidemia attenuates the cardioprotective effect of preconditioning via unknown mechanisms. We have reported previously that in normolipidemic rats, preconditioning decreased ischemia-induced activation and release of myocardial matrix metalloproteinase (MMP)-2 into the coronary perfusate. Here, we investigated whether hyperlipidemia interferes with the cardioprotective effect of preconditioning through modulation of MMP-2. Hearts isolated from male Wistar rats fed 2% cholesterol-enriched or control chow for 9 weeks were subjected to a preconditioning protocol (three intermittent periods of ischemia/reperfusion of 5-min duration each) or a time-matched nonpreconditioning protocol. This was followed by a test ischemia/reperfusion (30-min ischemia and 120-min reperfusion) in both groups. Preconditioning decreased infarct size in the control but not the cholesterol-fed group. Cardioprotection in the preconditioned control group but not in the cholesterol-fed group was associated with an 18 +/- 3% (p < 0.05) inhibition of test ischemia/reperfusion-induced activation and release of myocardial MMP-2 into the perfusate. Myocardial protein levels of tissue inhibitors of MMPs [tissue inhibitor of metalloproteinases (TIMP)-2 and TIMP-4] were not changed in either group. A reduction of infarct size in nonpreconditioned hearts from both control and cholesterol-fed group was produced by the MMP inhibitor ilomastat at 0.25 microM, a concentration producing MMP-2 inhibition comparable with that of preconditioning in the control group. We conclude that hyperlipidemia blocks preconditioning-induced cardioprotection, hyperlipidemia abolishes preconditioning-induced inhibition of myocardial MMP-2 activation and release, preconditioning-induced inhibition of MMP-2 activation and release is not mediated by TIMPs, and pharmacological inhibition of MMPs produces cardioprotection in both normal and hyperlipidemic rats.

Topics: Animals; Blotting, Western; Cholesterol, Dietary; Diet; Dose-Response Relationship, Drug; Enzyme Inhibitors; Hydroxamic Acids; Hyperlipidemias; Indoles; Ischemic Preconditioning, Myocardial; L-Lactate Dehydrogenase; Male; Matrix Metalloproteinase Inhibitors; Myocardial Infarction; Myocardium; Protease Inhibitors; Rats; Rats, Wistar; Tissue Inhibitor of Metalloproteinase-2; Tissue Inhibitor of Metalloproteinase-4; Tissue Inhibitor of Metalloproteinases; Tyrosine

We evaluated the effects of a 0.5% cholesterol-enriched diet (HCD) on nitric-oxide synthase (NOS) and arginase expression and the modulating role of 17beta-estradiol (E(2)) on this phenomenon. Thirty oopherectomized rabbits were divided into three groups and treated for 15 weeks. Group I received normal chow; group II, HCD; and group III, HCD plus E(2) pellets. Animals in group II showed an increase in plasma lipids, and they demonstrated atheromatous lesions as well as expression of arginase I and II accompanied by a significant number of BrdU-positive cells in endothelial cells and intimal muscle cells, suggestive of an increase in cellular proliferation. There was significant expression of inducible NOS and increased staining of nitrotyrosine-positive areas. These were not observed in group I animals. In both groups, E(2) levels were low. In group III animals, E(2) supplementation led to a decrease in atheromatous lesions and BrdU-positive cells and reduced expression of both inducible NOS and arginase I and II accompanied by a decrease in nitrotyrosine staining. E(2) levels were increased. Our results suggest that E(2) was responsible for these effects, despite the animals being hyperlipidemic, similar to those in group II. Because arginase is responsible for cell proliferation by converting l-arginine to polyamines, our results indicate that expression of arginase may play an important role in cellular proliferation in atherosclerosis, and inhibition of arginase expression by E(2) may be another potential mechanism in attenuating atherogenesis.

Topics: Animals; Arginase; Atherosclerosis; Bromodeoxyuridine; Cell Movement; Disease Models, Animal; Estradiol; Female; Gene Expression Regulation, Enzymologic; Hyperlipidemias; Immunohistochemistry; Lipids; Macrophages; Myocytes, Smooth Muscle; Nitric Oxide Synthase Type II; Rabbits; Tyrosine

Cigarette smoking is known to promote atherosclerosis, possibly through enhanced oxidative stress. The aim of the present study was to elucidate the possible involvement of peroxynitrite in oxidative modification of low-density lipoprotein (LDL) induced by aqueous extract of cigarette smoke (CSE) and the preventive effect of fluvastain, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor with antioxidative activity, in vitro and in vivo. Modification of LDL was monitored by LDL subfraction analysis using anion-exchange HPLC, TBARS formation and 3-nitrotyrosine production. Incubation of LDL with CSE caused a marked increase in oxidative modification of LDL and nitration of tyrosine residues in the apolipoprotein B. These modifications were prevented by treatment with fluvastatin as well as Vitamin E in a concentration-related manner. Fluvastatin was equal to or more effective than Vitamin E for preventing protein nitration, but weaker for preventing oxidative modification. When CSE was injected daily into the ear vein of Watanabe heritable hyperlipidemic rabbits for 5 months, both oxidative modification and nitration of the plasma LDL noticeably occurred. These changes induced by CSE could be effectively prevented by the simultaneous oral administration of fluvastatin (10 and 30 mg/kg) or Vitamin E (150 mg/kg). Fluvastatin prevented the LDL nitration more effectively than Vitamin E. These results suggest that peroxynitrite in CSE is involved in oxidative modification of LDL and that fluvastatin can efficiently prevent LDL modification by scavenging peroxynitrite. Fluvastatin may be potentially beneficial to hypercholesterolemic patients with oxidative stress such as smoking.

Topics: Animals; Antioxidants; Apolipoproteins; Fatty Acids, Monounsaturated; Female; Fluvastatin; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hyperlipidemias; In Vitro Techniques; Indoles; Lipoproteins, LDL; Male; Oxidation-Reduction; Oxidative Stress; Peroxynitrous Acid; Rabbits; Smoking; Tyrosine; Vitamin E

We investigated the influence of experimental hyperlipidemia on the formation of cardiac NO, superoxide, and peroxynitrite (ONOO(-)) in rat hearts.. Wistar rats were fed 2% cholesterol-enriched diet or normal diet for 8 weeks. Separate groups of normal and hyperlipidemic rats were injected twice intraperitoneally with 2 x 20 micromol/kg FeTPPS (5,10,15,20-tetrakis-[4-sulfonatophenyl]-porphyrinato-iron[III]), a ONOO(-) decomposition catalyst, 24 h and 1 h before isolation of the hearts.. A cholesterol diet significantly decreased myocardial NO content, however, myocardial Ca(2+)-dependent and Ca(2+)-independent NO synthase activity and NO synthase protein level did not change. Myocardial superoxide formation and xanthine oxidase activity were significantly increased; however, cardiac superoxide dismutase activity did not change in the cholesterol-fed group. Dityrosine in the perfusate, a marker of cardiac ONOO(-) formation, and plasma nitrotyrosine, a marker for systemic ONOO(-) formation, were both elevated in hyperlipidemic rats. In cholesterol-fed rats, left ventricular end-diastolic pressure (LVEDP) was significantly elevated as compared to controls. Administration of FeTPPS normalized LVEDP in the cholesterol-fed group.. We conclude that cholesterol-enriched diet-induced hyperlipidemia leads to an increase in cardiac ONOO(-) formation and a decrease in the bioavailability of NO which contributes to the deterioration of cardiac performance and may lead to further cardiac pathologies.

Topics: Animals; Biomarkers; Cholesterol, Dietary; Hyperlipidemias; Male; Malondialdehyde; Models, Animal; Myocardium; Nitric Oxide; Nitric Oxide Synthase; Peroxynitrous Acid; Rats; Rats, Wistar; Superoxide Dismutase; Superoxides; Tyrosine; Xanthine Dehydrogenase

With the present studies we sought to determine how treatment with nitroglycerin (NTG) affects endothelial function, oxidative stress and nitric oxide (NO)-downstream signaling in Watanabe heritable hyperlipidemic rabbits (WHHL).. In vitro experiments have demonstrated potent antiatherosclerotic effects of NO suggesting that treatment with NO-donors such as NTG could compensate for the diminished availability of endothelial NO. Nitric oxide may, however, not only be scavenged by reaction with endothelium-derived superoxide but also form the potent oxidant and inhibitor of vascular function, peroxynitrite (ONOO(-)).. Watanabe heritable hyperlipidemic rabbits were treated for three days with NTG patches. Normolipidemic New Zealand White rabbits (NZWR) served as controls. Endothelial function was assessed ex vivo with organ chamber experiments and vascular superoxide was quantified using lucigenin (5 and 250 microM) and CLA-enhanced chemiluminescence. Vascular ONOO(-) formation was determined using nitrotyrosine antibodies. The activity of the cGMP-dependent kinase (cGK-I) was assessed by determining the phosphorylation of vasodilator-stimulated phosphoprotein VASP (P-VASP).. Nitroglycerin treatment caused endothelial dysfunction in NZWR and WHHL, associated with an increase in superoxide and ONOO(-) production and a substantial drop in cGK-I activity. In vivo NTG-treatment decreased lipophilic antioxidants (alpha- and beta-carotene) in NZWR and WHHL. Treatment of NZWR with NTG also decreased plasma extracellular superoxide dismutase (EC-SOD)-activity.. Nitroglycerin treatment of WHHL with exogenous NO worsens rather than improves endothelial dysfunction secondary to increased formation of superoxide and/or peroxynitrite leading to decreased cGK-I activity. The decrease in plasma levels of alpha- and beta-carotene may be at least in part due to a decrease in EC-SOD activity.

Topics: Animals; Antioxidants; beta Carotene; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Drug Evaluation, Preclinical; Endothelium, Vascular; Free Radicals; Hyperlipidemias; Immunohistochemistry; Male; Nitric Oxide; Nitroglycerin; Oxidative Stress; Rabbits; Reactive Oxygen Species; Superoxide Dismutase; Tyrosine; Vasodilator Agents