Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The crucial role of nitric oxide (NO) for normal endothelial function is well known. In many conditions associated with increased risk of cardiovascular diseases such as hypercholesterolemia, hypertension, abdominal obesity, diabetes and smoking, NO biosynthesis is dysregulated, leading to endothelial dysfunction. The growing evidence from animal and human studies indicates that endogenous inhibitors of endothelial NO synthase such as asymmetric dimethylarginine (ADMA) and NG-monomethyl-L-arginine (L-NMMA) are associated with the endothelial dysfunction and potentially regulate NO synthase. The major route of elimination of ADMA is metabolism by the enzymes dimethylarginine dimethylaminohydrolase-1 and -2 (DDAH). In our recent study 16 men with either low or high plasma ADMA concentrations were screened to identify DDAH polymorphisms that could potentially be associated with increased susceptibility to cardiovascular diseases. In that study a novel functional mutation of DDAH-1 was identified; the mutation carriers had a significantly elevated risk for cardiovascular disease and a tendency to develop hypertension. These results confirmed the clinical role of DDAH enzymes in ADMA metabolism. Furthermore, it is possible that more common variants of DDAH genes contribute more widely to increased cardiovascular risk.
 ...
PMID:DDAH gene and cardiovascular risk. 1644 68

Asymmetric dimethylarginine (ADMA) is synthesized during the methylation of protein arginine residues by protein arginine methyltransferases (PRMT) and is released during proteolysis. ADMA is a competitive inhibitor of nitric oxide synthase and may decrease NO availability. ADMA is eliminated by renal excretion or is metabolized by dimethylarginine dimethylaminohydrolase (DDAH) to citruline and dimethylamine. Two other endogenous methylarginines are also synthesized by PRMT: N-monomethyl-L-arginine (L-NMMA) and symmetric dimethylarginine (SDMA). L-NMMA inhibits NO synthase but its concentrations in circulation are much lower than ADMA whereas SDMA is inactive. Plasma concentration of ADMA is markedly increased in patients with chronic renal failure and moderately increased in patients with many other diseases including hyperlipidemia, diabetes mellitus, arterial hypertension, hyperhomocysteinemia and heart failure. The increased concentration of ADMA is positively correlated with markers of atherosclerosis, such as carotid artery intima-media thickness and has a predictive value for acute cardiovascular events in prospective studies. Angiotensin-converting enzyme inhibitors, angiotensin AT1 receptor antagonists, vitamin E and, according to some studies, estrogens used in hormonal replacement therapy reduce plasma ADMA concentration, which may contribute to their beneficial effect on NO synthesis and endothelial function. However, in some states associated with excess of NO, such as septic shock or excitotoxic neuronal injury ADMA may be protective by limiting toxic effect of high concentrations of NO. This article reviews the effect of pharmacotherapy on ADMA metabolism and its possible clinical implications.
 ...
PMID:Asymmetric dimethylarginine (ADMA) as a target for pharmacotherapy. 1670 18

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase. ADMA is generated by protein methyltransferase (PRMT) and is metabolized mainly by dimethylarginine dimethylaminohydrolase (DDAH). ADMA levels are reported to increase in patients with chronic kidney disease (CKD), thereby playing a role in the pathogenesis of accelerated atherosclerosis in this population. However, the precise mechanism underlying ADMA accumulation in these patients is not fully understood. This study investigated the molecular mechanism for the elevation of ADMA levels in CKD, using a rat remnant kidney model that represents progressive CKD. After male Sprague-Dawley rats underwent baseline measurement of BP and renal function, 5/6 subtotal nephrectomy (5/6Nx) and 4/6 nephrectomy were performed. Plasma and urinary levels of ADMA and symmetric dimethylarginine, an inert isomer of ADMA, were measured by HPLC. Expression levels of PRMT genes and DDAH proteins were analyzed by semiquantitative reverse transcription-PCR and Western blotting, respectively. Plasma ADMA levels were elevated in the Nx groups in proportion to the degree of nephrectomy despite marked increases in renal clearance of ADMA. In contrast, renal clearance of symmetric dimethylarginine was decreased and its plasma levels were increased in the Nx groups. Furthermore, both liver and kidney gene expression of PRMT was increased, whereas DDAH protein expression was decreased in the 5/6Nx group. Plasma ADMA levels were correlated with systolic BP levels. Moreover, adenovirus-mediated DDAH gene transfer into the 5/6Nx rats prevented the elevation of BP levels, which was associated with the reduction of plasma and urinary ADMA levels. The results presented here suggest that decreased DDAH levels as well as increased PRMT gene expression could cause the elevation of plasma ADMA levels, thereby eliciting hypertension in CKD. Substitution of DDAH protein or enhancement of its activity may become a novel therapeutic strategy for the treatment of hypertension-related vascular injury in CKD.
 ...
PMID:Molecular mechanism for elevation of asymmetric dimethylarginine and its role for hypertension in chronic kidney disease. 1680 6

Left ventricular hypertrophy (LVH) is an early manifestation of cardiovascular target organ damage in patients with arterial hypertension. It is not only a target organ response to increased after-load, but is also the most potent cardiovascular risk factor. LVH is multifactorial sign which has several causative factors in addition to blood pressure. Asymmetrical dimethylarginine (ADMA) is an endogenous inhibitor of NO synthase. ADMA plasma levels have been shown to be elevated in diseases related to endothelial dysfunction such as hypertension, hyperlipidemia, diabetes mellitus. Because cardiac remodeling is associated with endothelial NO pathway, some recent studies investigated whether the plasma ADMA was related to LVH and found that there is a link between ADMA and left ventricular mass and geometry. ADMA was two times higher in patients with concentric LVH than in those normal controls. In many experimental systems, accumulation of ADMA is accompanied by reduced dimethylarginine dimethylaminohydrolase (DDAH) activity. Plasma ADMA is cleared in small part by urinary excretion, but the bulk of ADMA is degraded by DDAH. Therefore, we proposed that change in DDAH activity could disturb the metabolism of ADMA and result in hypertensive LVH through the ADMA/NO pathway.
 ...
PMID:Dimethylarginine dimethylaminohydrolase (DDAH)--a critical regulator of hypertensive left ventricular hypertrophy? 1798 7

The endothelium is a fundamental layer in the arterial wall both for the local regulation of flow to critical organs like the heart, brain and kidney, and for the protection of the vascular system from atherogenic insults. Inhibition of nitric oxide (NO) synthesis has profound effects at systemic and renal levels. Low NO bioavailability may occur in essential hypertension and in a variety of conditions associated with high cardiovascular risk. High oxidative stress and low availability of the substrate of NO-synthase, l-arginine, as well as an increase of endogenous NO inhibitors such as asymmetric dimethylarginine (ADMA) may engender endothelial dysfunction. This alteration is very frequent in patients with chronic kidney disease (CKD) and may contribute to accelerated progression of CKD, hypertension and cardiovascular complications. The kidney not only reabsorbs but also synthesizes l-arginine and appears to be a central organ for the catabolism of ADMA, mainly because it is richly endowed with the enzyme that degrades ADMA, dimethylarginine dimethylaminohydrolase (DDAH). Recent studies demonstrated that ADMA accumulation predicts both progression to end-stage renal disease and death in patients with CKD, again further suggesting that ADMA is a potentially important treatment target in clinical trials aimed at reducing the rate of loss of renal function in these patients.
 ...
PMID:The endothelium as a target in renal diseases. 1805 Jan 41

The aim of the present study was to investigate the role of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) and its degrading enzyme dimethylarginine dimethylaminohydrolase (DDAH) in angiotensin II (ANG II)-induced hypertension and target organ damage in mice. Mice transgenic for the human DDAH1 gene (TG) and wild-type (WT) mice (each, n = 28) were treated with 1.0 microg kg(-1) min(-1) ANG II, 3.0 microg kg(-1) min(-1) ANG II, or phosphate-buffered saline over 4 wk via osmotic minipumps. Blood pressure, as measured by tail cuff, was elevated to the same degree in TG and WT mice. Plasma levels of ADMA were lower in TG than WT mice and were not affected after 4 wk by either dose of ANG II in both TG and WT animals. Oxidative stress within the wall of the aorta, measured by fluorescence microscopy using the dye dihydroethidium, was significantly reduced in TG mice. ANG II-induced glomerulosclerosis was similar between WT and TG mice, whereas renal interstitial fibrosis was significantly reduced in TG compared with WT animals. Renal mRNA expression of protein arginine methyltransferase (PRMT)1 and DDAH2 increased during the infusion of ANG II, whereas PRMT3 and endogenous mouse DDAH1 expression remained unaltered. Chronic infusion of ANG II in mice has no effect on the plasma levels of ADMA after 4 wk. However, an overexpression of DDAH1 alleviates ANG II-induced renal interstitial fibrosis and vascular oxidative stress, suggesting a blood pressure-independent effect of ADMA on ANG II-induced target organ damage.
 ...
PMID:Role of asymmetric dimethylarginine for angiotensin II-induced target organ damage in mice. 1815 99

Telmisartan, in addition to blocking angiotensin (Ang) II type 1 receptor (AT(1)R), activates peroxisome proliferator activated receptor gamma (PPARgamma) signaling that interferes with nitric oxide (NO) system. Because aging of endothelial cells (ECs) is hallmarked by a reduction in NO synthesis, we hypothesized that telmisartan increases NO formation by regulated asymmetrical dimethylarginine (ADMA)-dimethylarginine dimethylaminohydrolase (DDAH)-system through blocking AT(1)R and activating PPARgamma signaling. To test this hypothesis, ECs were cultured with telmisartan, eprosartan, Ang II, and GW9662 (PPARgamma antagonist) until the twelfth passage. During the process of aging, PPARgamma protein expression decreased significantly, whereas the expression of AT(1)R increased. Telmisartan reversed these effects and dose-dependently decreased reactive oxygen species and 8-iso-prostaglandin (PG) F(2alpha) formation. This effect was associated with an upregulated activity and protein expression of DDAH, accompanied by a decrease in ADMA concentration, an increase in NO metabolites, and delayed senescence. Blockade of PPARgamma signaling by GW9662 or PPARgamma small-interference RNA prevented the effect of telmisartan on ADMA-DDAH-NO system. Coincubation with Ang II did not affect the effect of telmisartan-delayed senescence, whereas Ang II itself accelerated endothelial aging. Moreover, AT(1)R blocker eprosartan that did not influence PPARgamma protein expression had no effect on ADMA system and senescence. We have demonstrated that telmisartan mainly by activating PPARgamma signaling can alter the catabolism and release of ADMA as an important cardiovascular risk factor. We therefore propose that telmisartan translationally and posttranslationally upregulated DDAH expression via activation of PPARgamma signaling, causing ADMA to diminish and increase NO synthesis sufficient to delay senescence.
Hypertension 2008 Mar
PMID:Effect of telmisartan on nitric oxide--asymmetrical dimethylarginine system: role of angiotensin II type 1 receptor gamma and peroxisome proliferator activated receptor gamma signaling during endothelial aging. 1825 Mar 62

Asymmetric (N(G),N(G)) dimethylarginine (ADMA) is present in plasma and cells. It can inhibit nitric oxide synthase (NOS) that generates nitric oxide (NO) and cationic amino acid transporters (CATs) that supply intracellular NOS with its substrate, l-arginine, from the plasma. Therefore, ADMA and its transport mechanisms are strategically placed to regulate endothelial function. This could have considerable clinical impact since endothelial dysfunction has been detected at the origin of hypertension and chronic kidney disease (CKD) in human subjects and may be a harbinger of large vessel disease and cardiovascular disease (CVD). Indeed, plasma levels of ADMA are increased in many studies of patients at risk for, or with overt CKD or CVD. However, the levels of ADMA measured in plasma of about 0.5micromol.l(-1) may be below those required to inhibit NOS whose substrate, l-arginine, is present in concentrations many fold above the Km for NOS. However, NOS activity may be partially inhibited by cellular ADMA. Therefore, the cellular production of ADMA by protein arginine methyltransferase (PRMT) and protein hydrolysis, its degradation by N(G),N(G)-dimethylarginine dimethylaminohydrolase (DDAH) and its transmembrane transport by CAT that determines intracellular levels of ADMA may also determine the state of activation of NOS. This is the focus of the review. It is concluded that cellular levels of ADMA can be 5- to 20-fold above those in plasma and in a range that could tonically inhibit NOS. The relative importance of PRMT, DDAH and CAT for determining the intracellular NOS substrate:inhibitor ratio (l-arginine:ADMA) may vary according to the pathophysiologic circumstance. An understanding of this important balance requires knowledge of these three processes that regulate the intracellular levels of ADMA and arginine.
 ...
PMID:Cellular ADMA: regulation and action. 1968 80

Recent studies have shown that asymmetric dimethylarginine (ADMA), a nitric oxide synthase inhibitor, is increased in hypertension and chronic kidney disease. However, little is known about the effects of hypertension per se on ADMA metabolism. The purpose of this study was to test the hypothesis that ANG II-induced hypertension, in the absence of renal injury, is associated with increased oxidative stress and plasma and renal cortex ADMA levels in rats. Male Sprague-Dawley rats were treated with ANG II at 200 ng.kg(-1).min(-1) sc (by minipump) for 1 or 3 wk or at 400 ng.kg(-1).min(-1) for 6 wk. Mean arterial pressure was increased after 3 and 6 wk of ANG II; however, renal injury (proteinuria, glomerular sclerosis, and interstitial fibrosis) was only evident after 6 wk of treatment. Plasma thiobarbituric acid reactive substances concentration and renal cortex p22(phox) protein abundance were increased early (1 and 3 wk), but urinary excretion of isoprostane and H(2)O(2) was only increased after 6 wk of ANG II. An increased in plasma ADMA after 6 wk of ANG II was associated with increased lung protein arginine methyltransferase-1 abundance and decreased renal cortex dimethylarginine dimethylaminohydrolase activity. No changes in renal cortex ADMA were observed. ANG II hypertension in the absence of renal injury is not associated with increased ADMA; however, when the severity and duration of the treatment were increased, plasma ADMA increased. These data suggest that elevated blood pressure alone, for up to 3 wk, in the absence of renal injury does not play an important role in the regulation of ADMA. However, the presence of renal injury and sustained hypertension for 6 wk increases ADMA levels and contributes to nitric oxide deficiency and cardiovascular disease.
 ...
PMID:Asymmetric dimethylarginine in angiotensin II-induced hypertension. 2001 20

Asymmetrical dimethylarginine inhibits nitric oxide synthase, cationic amino acid transport, and endothelial function. Patients with cardiovascular risk factors often have endothelial dysfunction associated with increased plasma asymmetrical dimethylarginine and markers of reactive oxygen species. We tested the hypothesis that reactive oxygen species, generated by nicotinamide adenine dinucleotide phosphate oxidase, enhance cellular asymmetrical dimethylarginine. Incubation of rat preglomerular vascular smooth muscle cells with angiotensin II doubled the activity of nicotinamide adenine dinucleotide phosphate oxidase but decreased the activities of dimethylarginine dimethylaminohydrolase by 35% and of cationic amino acid transport by 20% and doubled cellular (but not medium) asymmetrical dimethylarginine concentrations (P<0.01). This was blocked by tempol or candesartan. Cells stably transfected with p22(phox) had a 50% decreased protein expression and activity of dimethylarginine dimethylaminohydrolase despite increased promoter activity and mRNA. The decreased DDAH protein expression and the increased asymmetrical dimethylarginine concentration in p22(phox)-transfected cells were prevented by proteosomal inhibition. These cells had enhanced protein arginine methylation, a 2-fold increased expression of protein arginine methyltransferase-3 (P<0.05) and a 30% reduction in cationic amino acid transport activity (P<0.05). Asymmetrical dimethylarginine was increased from 6+/-1 to 16+/-3 micromol/L (P<0.005) in p22(phox)-transfected cells. Thus, angiotensin II increased cellular asymmetrical dimethylarginine via type 1 receptors and reactive oxygen species. Nicotinamide adenine dinucleotide phosphate oxidase increased cellular asymmetrical dimethylarginine by increasing enzymes that generate it, enhancing the degradation of enzymes that metabolize it, and reducing its cellular transport. This could underlie increases in cellular asymmetrical dimethylarginine during oxidative stress.
Hypertension 2010 Sep
PMID:Angiotensin II and NADPH oxidase increase ADMA in vascular smooth muscle cells. 2069 82


<< Previous 1 2 3 4 5 Next >>