dimethylarginine and Disease-Models--Animal

Elevation of plasma homocysteine level is a risk factor for cardiovascular disease, stroke, and venous thromboembolism. It is still uncertain, however, whether hyperhomocysteinemia is a causative factor or a marker of vascular disease. The strongest evidence that homocysteine plays a causal role in atherothrombosis has been provided by studies using animal models. In the past decade, considerable progress in defining the vascular effects of hyperhomocysteinemia was achieved through the use of genetic and dietary approaches to induce hyperhomocysteinemia in experimental animals. A key vascular phenotype observed in hyperhomocysteinemic animals is endothelial dysfunction, manifested by decreased bioavailability of endothelium-derived nitric oxide. Impairment of endothelial function may be mediated by either accelerated oxidative inactivation of nitric oxide or inhibition of nitric oxide production caused by the endogenous nitric oxide synthase inhibitor, asymmetric dimethylarginine. Hyperhomocysteinemia also increases susceptibility to arterial thrombosis and accelerates the development of atherosclerosis in susceptible models such as the apolipoprotein E-deficient mouse. Mechanisms of atherothrombosis may include homocysteine-induced thiolation or acylation of plasma or endothelial proteins and endoplasmic reticulum stress, which activates signal transduction pathways leading to inflammation and apoptosis.

Topics: Animals; Apolipoproteins E; Apoptosis; Arginine; Atherosclerosis; Coronary Thrombosis; Cysteine; Disease Models, Animal; Endothelium, Vascular; Homocysteine; Humans; Hyperhomocysteinemia; Inflammation; Methionine; Mice; Models, Biological; Nitric Oxide; Oxidative Stress; Oxygen; Phenotype; Signal Transduction

Duchenne muscular dystrophy (DMD) is an X-linked disease caused by null mutations in dystrophin and characterized by muscle degeneration. Cardiomyopathy is common and often prevalent at similar frequency in female DMD carriers irrespective of whether they manifest skeletal muscle disease. Impaired muscle nitric oxide (NO) production in DMD disrupts muscle blood flow regulation and exaggerates postexercise fatigue. We show that circulating levels of endogenous methylated arginines including asymmetric dimethylarginine (ADMA), which act as NO synthase inhibitors, are elevated by acute necrotic muscle damage and in chronically necrotic dystrophin-deficient mice. We therefore hypothesized that excessive ADMA impairs muscle NO production and diminishes exercise tolerance in DMD. We used transgenic expression of dimethylarginine dimethylaminohydrolase 1 (DDAH), which degrades methylated arginines, to investigate their contribution to exercise-induced fatigue in DMD. Although infusion of exogenous ADMA was sufficient to impair exercise performance in wild-type mice, transgenic DDAH expression did not rescue exercise-induced fatigue in dystrophin-deficient male

Topics: Amidohydrolases; Animals; Arginine; Cardiomyopathies; Coronary Circulation; Disease Models, Animal; Exercise Tolerance; Female; Heterozygote; Male; Mice, Inbred C57BL; Mice, Inbred mdx; Mice, Transgenic; Muscular Dystrophy, Duchenne; Myocardium; Necrosis; Quadriceps Muscle; Ventricular Function, Left

Coal fly dust (CFD)-induced asthma model is used as an ambient particulate matter model of serious pulmonary damage. We aimed to evaluate the effects of a combination of ginseng and Salvia plebeia R. Br extract (KGC-03-PS; KG3P) and its individual components (hispidulin, nepetin and rosmarinic acid) in a CFD-induced mouse model of airway inflammation (asthma). We also evaluated signal transduction by KG3P and its individual components in the alveolar macrophage cell line, MH-S cells. In vitro, KG3P and its individual components inhibited nitric oxide production and expression of pro-inflammatory mediators and cytokines (iNOS, COX-2, IL-1β, IL-6 and TNF-α) through the NF-κB and MAPK pathways in coal fly ash (CFA)-induced inflammation in MH-S cells. Moreover, in the CFD-induced asthma model in mice, KG3P and its predominant individual component, nepetin, inhibited Asymmetric Dimethyl arginine (ADMA) and Symmetric Dimethyl arginine (SDMA) in serum, and decreased the histopathologic score in the lungs. A significant reduction in the neutrophils and immune cells in BALF and lung tissue was demonstrated, with significant reduction in the expression of the pro-inflammatory cytokines. Finally, IRAK-1 localization was also potently inhibited by KG3P and nepetin. Thus, KG3P extract can be considered as a potent candidate for amelioration of airway inflammation.

Topics: Animals; Arginine; Asthma; Bronchoalveolar Lavage Fluid; Coal; Coal Ash; Cytokines; Disease Models, Animal; Flavones; Herbal Medicine; Lung; Mice; Signal Transduction

Alterations in brain nitric oxide (NO)/cGMP synthesis contribute to the pathogenesis of hepatic encephalopathy (HE). An increased asymmetrically dimethylated derivative of L-arginine (ADMA), an endogenous inhibitor of NO synthases, was observed in plasma of HE patients and animal models. It is not clear whether changes in brain ADMA reflect its increased local synthesis therefore affecting NO/cGMP pathway, or are a consequence of its increased peripheral blood content. We measured extracellular concentration of ADMA and symmetrically dimethylated isoform (SDMA) in the prefrontal cortex of control and thioacetamide (TAA)-induced HE rats. A contribution of locally synthesized dimethylarginines (DMAs) in their extracellular level in the brain was studied after direct infusion of the inhibitor of DMAs synthesizing enzymes (PRMTs), S-adenosylhomocysteine (AdoHcy, 2 mM), or the methyl donor, S-adenosylmethionine (AdoMet, 2 mM), via a microdialysis probe. Next, we analyzed whether locally synthesized ADMA attains physiological significance by determination of extracellular cGMP. The expression of PRMT-1 was also examined. Concentration of ADMA and SDMA, detected by positive mode electrospray LC-DMS-MS/MS, was greatly enhanced in TAA rats and was decreased (by 30 %) after AdoHcy and AdoMet infusion. TAA-induced increase (by 40 %) in cGMP was unaffected after AdoHcy administration. The expression of PRMT-1 in TAA rat brain was unaltered. The results suggest that (i) the TAA-induced increase in extracellular DMAs may result from their effective synthesis in the brain, and (ii) the excess of extracellular ADMA does not translate into changes in the extracellular cGMP concentration and implicate a minor role in brain NO/cGMP pathway control.

Topics: Animals; Arginine; Cyclic GMP; Disease Models, Animal; Extracellular Space; Hepatic Encephalopathy; Liver Failure, Acute; Male; Prefrontal Cortex; Protein-Arginine N-Methyltransferases; Rats, Sprague-Dawley; RNA, Messenger; S-Adenosylhomocysteine; S-Adenosylmethionine; Signal Transduction

Intermittent claudication is a form of exercise intolerance characterized by muscle pain during walking in patients with peripheral artery disease (PAD). Endothelial cell and muscle dysfunction are thought to be important contributors to the etiology of this disease, but a lack of preclinical models that incorporate these elements and measure exercise performance as a primary end point has slowed progress in finding new treatment options for these patients. We sought to develop an animal model of peripheral vascular insufficiency in which microvascular dysfunction and exercise intolerance were defining features. We further set out to determine if pharmacological activation of 5'-AMP-activated protein kinase (AMPK) might counteract any of these functional deficits. Mice aged on a high-fat diet demonstrate many functional and molecular characteristics of PAD, including the sequential development of peripheral vascular insufficiency, increased muscle fatigability, and progressive exercise intolerance. These changes occur gradually and are associated with alterations in nitric oxide bioavailability. Treatment of animals with an AMPK activator, R118, increased voluntary wheel running activity, decreased muscle fatigability, and prevented the progressive decrease in treadmill exercise capacity. These functional performance benefits were accompanied by improved mitochondrial function, the normalization of perfusion in exercising muscle, increased nitric oxide bioavailability, and decreased circulating levels of the endogenous endothelial nitric oxide synthase inhibitor asymmetric dimethylarginine. These data suggest that aged, obese mice represent a novel model for studying exercise intolerance associated with peripheral vascular insufficiency, and pharmacological activation of AMPK may be a suitable treatment for intermittent claudication associated with PAD.

Topics: Aging; AMP-Activated Protein Kinases; Animals; Apolipoproteins E; Arginine; Cilostazol; Diet, High-Fat; Disease Models, Animal; Enzyme Activation; Enzyme Activators; Humans; Intermittent Claudication; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle Fatigue; Muscle, Skeletal; Nitric Oxide Synthase Type III; Obesity; Peripheral Vascular Diseases; Phosphodiesterase 3 Inhibitors; Physical Exertion; Tetrazoles; Vasodilator Agents

To investigate the protective effect of ethyl pyruvate (EP), an anti-oxidant agent, against ischemia-reperfusion injury in a rat model of ovarian torsion, considering biochemical and histopathological aspects.. Forty Wistar Albino rats were divided into five groups: Group I, sham operation; Group II, ischemia alone, Group III, ischemia-reperfusion; Group IV, ischemia-reperfusion+50 mg/kg EP; and Group V, ischemia-reperfusion+100 mg/kg EP. Through laparotomy, 360° torsion was performed and maintained for 3 h, and detorsion was maintained for a further 3 h. Intraperitoneal EP was given 30 min before the surgical procedure. Ovarian tissues and blood samples were obtained after surgery. Malondialdehyde (MDA) and asymmetric dimethyl arginine (ADMA) levels were measured in both plasma and tissue samples. Tissue sections were evaluated histopatologically. Analysis of variance was used for statistical analyses.. In both serum and tissue samples, ADMA and MDA levels were found to be significantly lower in the EP groups compared with the ischemia alone and ischemia-reperfusion groups (p=0.0001). However, no significant difference was found between groups treated with 50 mg/kg or 100 mg/kg EP. On histopathological evaluation, the total tissue injury score was found to be lower in rats treated with EP. No significant difference was detected between groups treated with 50 mg/kg or 100 mg/kg EP.. Ethyl pyruvate may exert positive effects in ischemia-reperfusion injury in cases of ovarian torsion. However, no difference was detected between 50 mg/kg and 100 mg/kg EP.

Topics: Animals; Antioxidants; Arginine; Disease Models, Animal; Female; Malondialdehyde; Ovary; Pyruvates; Rats; Rats, Wistar; Reperfusion Injury; Torsion Abnormality

The present study investigated the effects of 3'-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA), the active principle compound of kimchi, on vascular damage in the experimental atherosclerotic animal. HDMPPA was administrated by an intraperitoneal injection of 10 mg/kg per d for 8 weeks to apoE knockout (KO) mice with an atherogenic diet containing 1 % cholesterol, and its effects were compared with vehicle-treated control mice. HDMPPA increased NO content in the aorta, accompanied by a decrease in reactive oxygen species (ROS) concentration. Furthermore, in the HDMPPA-treated group, aortic endothelial NO synthase (eNOS) expression was up-regulated compared with the control group. These results suggested that HDMPPA could maintain NO bioavailability through an increasing eNOS expression and preventing NO degradation by ROS. Furthermore, HDMPPA treatment in apoE KO mice inhibited eNOS uncoupling through an increase in vascular tetrahydrobiopterin content and a decrease in serum asymmetric dimethylarginine levels. Moreover, HDMPPA ameliorates inflammatory-related protein expression in the aorta of apoE KO mice. Therefore, the present study suggests that HDMPPA, the active compound of kimchi, a Korean functional food, may exert its vascular protective effect through the preservation of NO bioavailability and suppression of the inflammatory response.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aorta; Aortitis; Apolipoproteins E; Arginine; Atherosclerosis; Biopterins; Cell Adhesion Molecules; Diet, Atherogenic; Disease Models, Animal; Down-Regulation; Injections, Intraperitoneal; Male; Mice; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase Type III; Phenyl Ethers; Propionates; Random Allocation; Reactive Oxygen Species; Up-Regulation

Increased basal release of nitric oxide (NO) in the splanchnic circulation contributes to elevated plasma levels of NO observed in decompensated cirrhosis. We evaluated in rat mesenteric arteries whether the differences in basal release of NO, revealed by asymmetric dimethylarginine (ADMA)- and N(G) -nitro-L-arginine methyl ester (L-NAME)-induced contractions, were associated with changes in messenger RNA (mRNA) expression of endothelial NO synthase (eNOS) and dimethylarginine dimethylaminohydrolases (DDAHs).. Rat small mesenteric arteries from 14 Sham-control, from 14 with partial portal vein ligation (PPVL), and from 14 with bile duct excision (BDE)-induced cirrhosis were precontracted under isometric conditions with norepinephrine, and additional contractions were induced with ADMA and L-NAME. mRNA expression of eNOS, DDAH-1, and DDAH-2 in mesenteric arteries were evaluated by real-time polymerase chain reaction.. ADMA and L-NAME caused concentration- and endothelium-dependent contractions. pD2 values to L-NAME were similar in all groups. In contrast, pD2 values to ADMA were similar in PPVL and BDE but were significantly lower than those of the L-NAME and the Sham groups. Relaxation to acetylcholine was not modified by ADMA or L-NAME but was abolished by charybdotoxin plus apamin. There was an increased mRNA expression of eNOS, DDAH-1, and DDAH-2 in mesenteric arteries from PPVL and BDE compared with the Sham group.. Basal release of NO is increased in mesenteric arteries of PPVL and BDE rats. The rise in expression of DDAHs indicates a higher degradation of ADMA. This would result in an increased generation of endothelial NO and mesenteric vasodilation.

Topics: Amidohydrolases; Animals; Arginine; Disease Models, Animal; Endothelium, Vascular; Hypertension, Portal; In Vitro Techniques; Liver Cirrhosis, Experimental; Male; Mesenteric Arteries; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; Vasodilation

Asymmetric dimethylarginine is an endogenous inhibitor of NO synthesis that may mediate cardiovascular disease. Alanine-glyoxylate aminotransferase-2 (AGXT2) has been proposed to degrade asymmetric dimethylarginine. We investigated the significance of AGXT2 in methylarginine metabolism in vivo and examined the effect of this enzyme on blood pressure.. In isolated mouse kidney mitochondria, we show asymmetric dimethylarginine deamination under physiological conditions. We demonstrate increased asymmetric dimethylarginine, reduced NO, and hypertension in an AGXT2 knockout mouse. We provide evidence for a role of AGXT2 in methylarginine metabolism in humans by demonstrating an inverse relationship between renal (allograft) gene expression and circulating substrate levels and an association between expression and urinary concentrations of the product. Finally, we examined data from a meta-analysis of blood pressure genome-wide association studies. No genome-wide significance was observed, but taking a hypothesis-driven approach, there was a suggestive association between the T allele at rs37369 (which causes a valine-isoleucine substitution and altered levels of AGXT2 substrate) and a modest increase in diastolic blood pressure (P=0.0052).. Although the effect of variation at rs37369 needs further study, these findings suggest that AGXT2 is an important regulator of methylarginines and represents a novel mechanism through which the kidney regulates blood pressure.

Topics: Adult; Animals; Arginine; Blood Pressure; Disease Models, Animal; Female; Humans; Hypertension; Kidney; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Mitochondria; Nitric Oxide; Transaminases

Reduced bioavailability of endogenous nitric oxide (NO) is a central pathophysiological event in hypertension and other cardiovascular diseases. Recently, it was demonstrated that inorganic nitrate from dietary sources is converted in vivo to form nitrite, NO, and other bioactive nitrogen oxides. We tested the hypothesis that dietary inorganic nitrate supplementation may have therapeutic effects in a model of renal and cardiovascular disease.. Sprague-Dawley rats subjected to unilateral nephrectomy and chronic high-salt diet from 3 weeks of age developed hypertension, cardiac hypertrophy and fibrosis, proteinuria, and histological as well as biochemical signs of renal damage and oxidative stress. Simultaneous nitrate treatment (0.1 or 1 mmol nitrate kg⁻¹ day⁻¹), with the lower dose resembling the nitrate content of a diet rich in vegetables, attenuated hypertension dose-dependently with no signs of tolerance. Nitrate treatment almost completely prevented proteinuria and histological signs of renal injury, and the cardiac hypertrophy and fibrosis were attenuated. Mechanistically, dietary nitrate restored the tissue levels of bioactive nitrogen oxides and reduced the levels of oxidative stress markers in plasma (malondialdehyde) and urine (Class VI F2-isoprostanes and 8-hydroxy-2-deoxyguanosine). In addition, the increased circulating and urinary levels of dimethylarginines (ADMA and SDMA) in the hypertensive rats were normalized by nitrate supplementation.. Dietary inorganic nitrate is strongly protective in this model of renal and cardiovascular disease. Future studies will reveal if nitrate contributes to the well-known cardioprotective effects of a diet rich in vegetables.

Topics: Animals; Arginine; Blood Pressure; Cardiomegaly; Disease Models, Animal; Hypertension, Renal; Kidney; Male; Nephrectomy; Nitrates; Nitric Oxide; Nitrogen; Oxidative Stress; Proteinuria; Rats; Rats, Sprague-Dawley; Sodium Chloride, Dietary

Asymmetric dimethylarginine (ADMA) and N(G) monomethyl-L-arginine (L-NMMA) are endogenous inhibitors of nitric oxide synthases (NOS) and their local concentration is determined by the activity of dimethylarginine dimethylaminohydrolases (DDAHs). The current study in male Wistar rats was designed to immunolocalise DDAH I and II in relation to NOS and to investigate changes in distribution, activity and ADMA content in the acute period following myocardial infarction (MI) resulting from coronary artery ligation. Seven days after the coronary artery ligation, L-Arg and methylated arginine content, as well as DDAH activity were determined in homogenates of left ventricular (LV) infarct and border. The distribution of immunoreactive DDAH I, DDAH II, eNOS and iNOS were determined in sections of LV. In healthy hearts, DDAH I was absent, however, DDAH II was localized to endothelium and endocardium with a similar distribution to that of eNOS. Following MI, LV DDAH activity was increased (to 210+/-19% of control, P<0.05). Both DDAH I and DDAH II proteins were detected in peri-infarct cardiomyocytes, while DDAH II immunoreactivity was additionally localized to infiltrating inflammatory cells and blood vessels in the healing infarct. Both plasma and LV concentrations of the DDAH substrate, ADMA, were increased post-MI, although the ratio of Arg:ADMA was retained in the LV post-MI relative to sham operated controls. In conclusion, DDAH II has a distribution similar to eNOS in healthy myocardium. The increased levels and activity of DDAH I and DDAH II enzymes following myocardial infarction suggest a potential role for them in local protection of NOS enzymes from inhibition by methylated arginines during infarct healing.

Topics: Amidohydrolases; Animals; Aorta; Arginine; Disease Models, Animal; Endocardium; Heart Ventricles; Male; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Protein-Arginine N-Methyltransferases; Rats; Rats, Wistar

Atrial fibrillation (AF) may cause thrombus formation in the left atrial appendage (LAA). Thrombus formation is associated with LAA endocardial dysfunction. Because asymmetrical dimethylarginine (ADMA) can cause endothelial dysfunction by decreasing nitric oxide (NO) formation, we investigated plasma ADMA and nitrite/nitrate (NO(X)) levels and myocardial dimethylarginine dimethylaminohydrolase-2 (DDAH-2), protein arginine methyltransferase-1 (PRMT-1), and endothelial NO synthase (eNOS) protein contents from AF dogs. The results displayed that plasma ADMA level significantly increased, and plasma NO(X) concentration significantly decreased. Compared with normal heart, DDAH-2 expression was unchanged in the fibrillating atria. However, the DDAH activity was significantly decreased in the fibrillating atria. PRMT-1 expression significantly increased in the LAA and in the left atrium (LA). ENOS expression significantly decreased in the LA. ENOS and PRMT-1 expressions were unchanged in the right atria. Our results suggested that the DDAH-PRMT-ADMA system maybe play a pivotal role in regulating endothelial function in AF.

Topics: Amidohydrolases; Animals; Arginine; Atrial Fibrillation; Disease Models, Animal; Dogs; Down-Regulation; Endothelium; Female; Male; Myocardium; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Protein-Arginine N-Methyltransferases; Thrombosis; Up-Regulation

In the context of the hypercatabolic response to stress, critically ill patients reveal hyperglycemia and elevated levels of asymmetrical-dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthases. Both hyperglycemia and elevated ADMA levels predict increased morbidity and mortality. Tight glycemic control by intensive insulin therapy lowers circulating ADMA levels, and improves morbidity and mortality. Methylarginines are released from proteins during catabolism. ADMA is predominantly cleared by the enzyme dimethylarginine-dimethylaminohydrolase (DDAH) in different tissues, whereas its symmetrical isoform (SDMA) is cleared via the kidneys. Therefore, glycemic control or glycemia-independent actions of insulin on protein breakdown and/or on DDAH activity resulting in augmented ADMA levels may explain part of the clinical benefit of intensive insulin therapy. Therefore, we investigated in our animal model of prolonged critical illness the relative impact of maintaining normoglycemia and of glycemia-independent action of insulin over 7 d in a four-arm design on plasma and tissue levels of ADMA and SDMA, on proteolysis as revealed by surrogate parameters as changes of body weight, plasma urea to creatinine ratio, and plasma levels of SDMA, and on tissue DDAH activity. We found that ADMA levels remained normal in the two normoglycemic groups and increased in hyperglycemic groups. SDMA levels in the investigated tissues remained largely unaffected. The urea to creatinine ratio indicated reduced proteolysis in all but normoglycemic/normal insulin animals. DDAH activity deteriorated in hyperglycemic compared with normoglycemic groups. Insulin did not affect this finding independent of glycemic control action. Conclusively, maintenance of normoglycemia and not glycemia-independent actions of insulin maintained physiological ADMA plasma and tissue levels by preserving physiological DDAH activity.

Topics: Amidohydrolases; Animals; Arginine; Blood Glucose; Body Weight; Creatinine; Critical Illness; Disease Models, Animal; Humans; Insulin; Rabbits

Cardiovascular events are accelerated in chronic kidney disease (CKD). Although deranged nitric oxide (NO) pathways and asymmetric dimethylarginine (ADMA) cause endothelial dysfunction, no direct evidence for coronary artery endothelial dysfunction in CKD has been documented. CKD was induced in male dogs by heminephrectomy (1/2Nx) or five-sixths nephrectomy (5/6Nx). After 4 wk, renal ablation reduced GFR (control 76 [54 to 85]; 1/2Nx 38 [29 to 47]; 5/6Nx 15 [12 to 46] ml/min) and elevated plasma ADMA (control 1.88 [1.68 to 2.54]; 1/2Nx 2.51 [2.11 to 3.55]; 5/6Nx 3.84 [2.16 to 3.95] micromol/L). Coronary circulatory responses to acetylcholine revealed marked increases in coronary blood flow in control group (83 +/- 17% increment) but blunted responses in 1/2Nx (34 +/- 8% increment) and 5/6Nx (20 +/- 4% increment). The acetylcholine-induced changes in epicardial arteriolar diameter, using needle-lens probe charge-coupled device videomicroscopy, showed similar results. The responsiveness to sodium nitroprusside did not differ among three groups. Plasma nitrite/nitrate levels decreased in 1/2Nx and 5/6Nx, and the mRNA expressions of dimethylarginine dimethylaminohydrolase-II (DDAH-II), ADMA-degrading enzyme, and endothelial NO synthase (eNOS) in coronary arteries were downregulated in 1/2Nx and 5/6Nx. Finally, 4-wk treatment with all-trans retinoic acid restored the impaired endothelium-dependent vasodilation and reversed the expression of eNOS but not DDAH-II. Coronary endothelial function is impaired in the early stage of CKD. The dysfunction is attributed to the downregulation of eNOS and/or DDAH-II in coronary arteries. Furthermore, the manipulation of NO pathways may constitute a therapeutic strategy for the prevention of coronary dysfunction in CKD.

Topics: Acetylcholine; Amidohydrolases; Animals; Arginine; Coronary Circulation; Disease Models, Animal; Dogs; Endothelium-Dependent Relaxing Factors; Endothelium, Vascular; Glomerular Filtration Rate; Kidney Failure, Chronic; Male; Microscopy, Video; Nitric Oxide; Nitric Oxide Synthase Type III; Nitroprusside; Tretinoin; Vasodilation; Vasodilator Agents

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, is mainly degraded by dimethylarginine dimethylaminohydrolase (DDAH). It was recently reported that reduced DDAH expression could contribute to ADMA accumulation and subsequent elevation of BP in an experimental model of chronic kidney disease (CKD). ADMA is a strong predictor of the progression of CKD as well. However, a role for the ADMA-DDAH in the pathogenesis of CKD remains to be elucidated. This study investigated the effects of DDAH-elicited ADMA lowering on renal function and pathology in a rat remnant kidney model. Four weeks after five-sixths subtotal nephrectomy (Nx), the rats were given tail-vein injections of recombinant adenovirus vector encoding DDAH-I (Adv-DDAH) or control vector expressing bacterial beta-galactosidase (Adv-LZ) or orally administered 20 mg/kg per d hydralazine (Hyz), which served as a BP control model. In comparison with Adv-LZ or Hyz administration, Adv-DDAH decreased plasma levels of ADMA and inhibited the deterioration of renal dysfunction. Plasma levels of ADMA were associated with decreased number of peritubular capillaries, increased tubulointerstitial fibrosis, and proteinuria levels in Nx rats. These changes were progressed in Adv-LZ-or Hyz-treated Nx rats, which were ameliorated by DDAH overexpression. In addition, semiquantitative reverse transcriptase-PCR and immunohistochemistry for TGF-beta revealed that Adv-DDAH inhibited upregulation of TGF-beta expression in Nx rats. These data suggest that ADMA may be involved in peritubular capillary loss and tubulointerstitial fibrosis, thereby contributing to the progression of CKD. Substitution of DDAH protein or enhancement of its activity may become a novel therapeutic strategy for the treatment of CKD.

Topics: Amidohydrolases; Animals; Arginine; Capillaries; Chronic Disease; Disease Models, Animal; Disease Progression; Fibrosis; Gene Expression Regulation, Enzymologic; Genetic Therapy; Kidney; Kidney Diseases; Male; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta

Previous investigations have shown that the level of asymmetric dimethylarginine (ADMA) was increased in hypercholesterolemic animal and humans, and the decreased erythrocyte deformability has been suggested to be a factor contributing to atherogenesis. In the present study, we investigated the effect of ADMA, endogenous or exogenous, on atherogenesis and erythrocyte deformability in apolipoprotein E deficient (ApoE-/-) mice. On a regular chow diet, ApoE-/- mice or C57BL/6 J mice at 12 weeks of age were treated with ADMA (5 mg/kg/day) for 4 weeks. Atherosclerotic lesion area, erythrocyte deformability, plasma lipids and asymmetric dimethylarginine (ADMA) level were determined. Plasma concentrations of triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC), ADMA, and atherosclerotic lesion area were significantly increased, and the level of plasma high-density lipoprotein-cholesterol (HDL-C), erythrocyte deformability in ApoE-/- mice were markedly decreased compared with that of C57BL/6J mice (P<0.05 or P<0.01). Exogenous ADMA treatment increased the plasma TG level, produced atherosclerotic lesions, and decreased erythrocyte deformability in C57BL/6J mice (P<0.05 or P<0.01). Treatment with exogenous ADMA further increased the plasma TG level and lesion areas, and decreased erythrocyte deformability in ApoE-/- mice. In vitro, exogenous ADMA caused a decrease of erythrocyte deformability in a concentration-dependent manner, and the effect of ADMA was reversed by L-arginine. The present results suggest that endogenous ADMA is an important contributor to the development of atherosclerosis and that reduction of erythrocyte deformability and impaired endothelial function induced by ADMA may be an important factor facilitating atherosclerotic lesions.

Topics: Animals; Aorta; Apolipoproteins E; Arginine; Atherosclerosis; Disease Models, Animal; Erythrocyte Deformability; Lipids; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Rats

The objective of this study was to determine whether the long-term administration of an HMG-CoA reductase inhibitor, atorvastatin, confers protective effects against stroke events in stroke-prone spontaneously hypertensive rats (SHRSPs). Atorvastatin (2 mg/kg, 20 mg/kg) or vehicle was orally administered to 8-week-old SHRSPs for 11 weeks. The survival ratio and stroke incidence were calculated, and plasma lipids and plasma levels of asymmetric dimethylarginine (ADMA), a circulating endogenous competitive inhibitor of NO synthase, were measured after sacrifice. The effect of atorvastatin on local cerebral blood flow (l-CBF) was also determined in 13-week-old SHRSPs after treatment with 20 mg/kg atorvastatin daily for 5 weeks. The survival ratios at 19 weeks of age were 15, 30, and 50% in the vehicle, low-dose (2 mg/kg), and high-dose groups (20 mg/kg), respectively. The survival ratio was significantly higher in the high-dose group than in the vehicle group. The incidence of stroke was significantly lower in the high-dose group than in the vehicle group. The levels of ADMA were 0.81+/-0.18 (mean+/-S.D.), 0.62+/-0.09, and 0.61+/-0.06 micromol/l in the vehicle, low-dose, and high-dose groups, respectively. Atorvastatin administration significantly reduced the ADMA levels without affecting the levels of plasma lipids. The level of l-CBF tended to be higher in the treated group, but not to a significant extent. Thus, atorvastatin was determined to confer a protective effect against hypertension-based stroke. The data suggest that the efficacy of the statin for stroke protection may be partially involved in the improvement of endothelial function via NO production and reduction of ADMA. Statins may confer useful protection against not only atherosclerosis-based stroke, but also hypertension-based stroke.

Topics: Animals; Arginine; Atorvastatin; Brain; Cerebral Arteries; Cerebrovascular Circulation; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Endothelial Cells; Heptanoic Acids; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertension; Lipid Metabolism; Male; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Synthase; Pyrroles; Rats; Rats, Inbred SHR; Stroke; Survival Rate; Time; Time Factors; Treatment Outcome

Recently, both asymmetrical dimethylarginine and IL-6 have been suggested to be associated with the induction and severity of single and multiple organ dysfunction. The aims of the present study were to elucidate if these factors were increased in an ischemia reperfusion (IR) model and whether pre-operative carbohydrate supplementation can reduce the risk factors along with the IR injury.. One group of male Wistar rats was fasted for 16 h (water ad libitum) prior to clamping the superior mesenteric artery (IR fasted n=14). A second group had ad libitum access to a carbohydrate solution prior to clamping (IR fasted CHO group n=11). Sham-fasted animals, which only received laparotomy and no clamping, served as controls (n=4).. Plasma urea and ALAT activity were both increased in the IR fasted animals when compared to the sham rats (P=0.007 and P<0.02, respectively). Furthermore, it was shown that IR fasted rats had increased ADMA and IL-6 concentration in plasma when compared to sham animals (P<0.02). Moreover, the GSH level in lung was significantly decreased in the IR fasted animals (P=0.014). IR CHO supplemented showed no significant increase of ALAT activity and decrease of lung GSH. Furthermore, significantly lower plasma urea, ADMA and IL-6 concentration was seen in the IR CHO supplemented group when compared to the IR fasted rats (P=0.028, P<0.01 and P<0.02, respectively). The liver glycogen concentration in IR fasted rats was 48% of that IR rats supplemented the carbohydrate mixture.. The present rat intestinal ischemia reperfusion model not only induces organ injury indicated by the classical parameters such as plasma urea and ALAT activity, but also increased plasma IL-6 and ADMA and decreased lung GSH concentration in IR fasted rats. Pre-operative supplementation with the carbohydrate mixture significantly lowered the plasma urea, IL-6 and ADMA concentrations and maintained lung GSH concentration. This indicates that pre-operative carbohydrate supplementation reduces post-operative organ injury.

Topics: Alanine Transaminase; Animals; Arginine; Blood Urea Nitrogen; Dietary Carbohydrates; Dietary Supplements; Disease Models, Animal; Glutathione; Glycogen; Interleukin-6; Liver; Male; Multiple Organ Failure; Preoperative Care; Random Allocation; Rats; Rats, Wistar; Reperfusion Injury; Risk Factors

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthase enzymes, whereas symmetric dimethylarginine (SDMA) competes with arginine transport. Although both dimethylarginines may be important regulators of the arginine-NO pathway, their metabolism is largely unknown. In previous studies, evidence was found for the liver in the metabolism of dimethylarginines. We aimed to investigate dimethylarginine handling of the gut and the liver in detail under basal conditions and during endotoxemia.. Twenty-one male Wistar rats were used for this study. Endotoxemia was induced by lipopolysaccharide (LPS) infusion (8 mg/kg). Blood flow was measured using radiolabeled microspheres according to the reference sample method. Concentration of dimethylarginines were measured by high-performance liquid chromatography. The combination of arteriovenous concentration difference and organ blood flow allowed calculation of net organ fluxes and fractional extraction (FE) rates.. Arterial plasma concentration of ADMA was lower in LPS rats, in contrast to a higher SDMA concentration. For the gut, net release of ADMA was found, which was higher in LPS rats. In contrast, for the gut, net uptake of SDMA was found, which was lower in LPS rats. For the liver, a high net uptake of ADMA was found in both groups, while FE was significantly increased in LPS rats. Hepatic handling of SDMA was negligible.. The liver plays an important role in eliminating ADMA from the circulation and endotoxemia stimulates this capacity. In contrast to the liver, the gut releases ADMA. Endotoxemia results in a reduced systemic ADMA concentration.

Topics: Animals; Arginine; Disease Models, Animal; Endotoxemia; Gastrointestinal Tract; Lipopolysaccharides; Liver; Male; Rats; Rats, Wistar; Regional Blood Flow; Splanchnic Circulation; Viscera