Chronic l-arginine treatment reduces vascular smooth muscle cell hypertrophy through cell cycle modifications in spontaneously hypertensive rats

Nitrosative Stress and Its Association with Cardiometabolic Disorders

Reactive nitrogen species (RNS) are formed when there is an abnormal increase in the level of nitric oxide (NO) produced by the inducible nitric oxide synthase (iNOS) and/or by the uncoupled endothelial nitric oxide synthase (eNOS). The presence of high concentrations of superoxide anions (O₂⁻) is also necessary for their formation. RNS react three times faster than O₂⁻ with other molecules and have a longer mean half life. They cause irreversible damage to cell membranes, proteins, mitochondria, the endoplasmic reticulum, nucleic acids and enzymes, altering their activity and leading to necrosis and to cell death. Although nitrogen species are important in the redox imbalance, this review focuses on the alterations caused by the RNS in the cellular redox system that are associated with cardiometabolic diseases. Currently, nitrosative stress (NSS) is implied in the pathogenesis of many diseases. The mechanisms that produce damage remain poorly understood. In this paper, we summarize the current knowledge on the participation of NSS in the pathology of cardiometabolic diseases and their possible mechanisms of action. This information might be useful for the future proposal of anti-NSS therapies for cardiometabolic diseases.

Newly manufactured Marukome MK-34-1 miso with angiotensin-converting enzyme inhibitory activity and its antihypertensive effects in genetic hypertensive rat models

We newly manufactured miso rich in angiotensin-converting enzyme (ACE) inhibitory activity (Marukome MK-34-1, shinki miso) and investigated its antihypertensive properties in rat models of genetic hypertension. ACE inhibitory activity was tenfold higher in shinki miso than in commercially available Marukome Nenrin miso (nenrin miso). The inhibitory activity of shinki miso was confined to <3 kDa fractions and was detected in several fractions with high polarity by C₁₈ high-performance liquid chromatography. Systolic blood pressure (SBP) increased age-dependently in stroke-prone spontaneously hypertensive rats (SHRSP/Izm) given a 0.6% (w/v) NaCl solution (salt solution group) that matched the salt content of the miso solutions. This SBP increase was attenuated in both the 5% nenrin and 5% shinki miso solution groups compared to the salt solution group. The reduction in SBP was greater in rats fed shinki than in rats fed nenrin miso. Similarly, in a salt-induced hypertension model with Dahl rats, the 5% nenrin miso solution attenuated the rising SBP observed in the salt solution group. Moreover, combining 5% nenrin miso with 5% shinki miso (2:1, v/v) (awase miso group) significantly decreased the SBP per gram salt intake by 8% compared with the nenrin miso treatment. However, there were no differences in urinary Na excretion between the nenrin and awase miso groups. In conclusion, we produced a new miso with potent ACE inhibitory activity that reduced spontaneous and salt-induced hypertension. These results suggest that salt sensitivity is decreased by the addition of shinki miso to nenrin miso.

Identify potential drugs for cardiovascular diseases caused by stress-induced genes in vascular smooth muscle cells

BACKGROUND

Abnormal proliferation of vascular smooth muscle cells (VSMC) is a major cause of cardiovascular diseases (CVDs). Many studies suggest that vascular injury triggers VSMC dedifferentiation, which results in VSMC changes from a contractile to a synthetic phenotype; however, the underlying molecular mechanisms are still unclear.

METHODS

In this study, we examined how VSMC responds under mechanical stress by using time-course microarray data. A three-phase study was proposed to investigate the stress-induced differentially expressed genes (DEGs) in VSMC. First, DEGs were identified by using the moderated t-statistics test. Second, more DEGs were inferred by using the Gaussian Graphical Model (GGM). Finally, the topological parameters-based method and cluster analysis approach were employed to predict the last batch of DEGs. To identify the potential drugs for vascular diseases involve VSMC proliferation, the drug-gene interaction database, Connectivity Map (cMap) was employed. Success of the predictions were determined using in-vitro data, i.e. MTT and clonogenic assay.

RESULTS

Based on the differential expression calculation, at least 23 DEGs were found, and the findings were qualified by previous studies on VSMC. The results of gene set enrichment analysis indicated that the most often found enriched biological processes are cell-cycle-related processes. Furthermore, more stress-induced genes, well supported by literature, were found by applying graph theory to the gene association network (GAN). Finally, we showed that by processing the cMap input queries with a cluster algorithm, we achieved a substantial increase in the number of potential drugs with experimental IC50 measurements. With this novel approach, we have not only successfully identified the DEGs, but also improved the DEGs prediction by performing the topological and cluster analysis. Moreover, the findings are remarkably validated and in line with the literature. Furthermore, the cMap and DrugBank resources were used to identify potential drugs and targeted genes for vascular diseases involve VSMC proliferation. Our findings are supported by in-vitro experimental IC50, binding activity data and clinical trials.

CONCLUSION

This study provides a systematic strategy to discover potential drugs and target genes, by which we hope to shed light on the treatments of VSMC proliferation associated diseases.

Liver growth factor treatment restores cell-extracellular matrix balance in resistance arteries and improves left ventricular hypertrophy in SHR

Liver growth factor (LGF) is an endogenous albumin-bilirubin complex with antihypertensive effects in spontaneously hypertensive rats (SHR). We assessed the actions of LGF treatment on SHR mesenteric resistance and intramyocardial arteries (MRA and IMA, respectively), heart, and vascular smooth muscle cells (VSMC). SHR and Wistar-Kyoto (WKY) rats treated with vehicle or LGF (4.5 μg LGF/rat, 4 ip injections over 12 days) were used. Intra-arterial blood pressure was measured in anesthetized rats. The heart was weighted and paraffin-embedded. Proliferation, ploidy, and fibronectin deposition were studied in carotid artery-derived VSMC by immunocytochemistry. In MRA, we assessed: 1) geometry and mechanics by pressure myography; 2) function by wire myography; 3) collagen by sirius red staining and polarized light microscopy, and 4) elastin, cell density, nitric oxide (NO), and superoxide anion by confocal microscopy. Heart sections were used to assess cell density and collagen content in IMA. Left ventricular hypertrophy (LVH) regression was assessed by echocardiography. LGF reduced blood pressure only in SHR. LGF in vitro or as treatment normalized the alterations in proliferation and fibronectin in SHR-derived VSMC with no effect on WKY cells. In MRA, LGF treatment normalized collagen, elastin, and VSMC content and passive mechanical properties. In addition, it improved NO availability through reduction of superoxide anion. In IMA, LGF treatment normalized perivascular collagen and VSMC density, improving the wall-to-lumen ratio. Paired experiments demonstrated a partial regression of SHR LVH by LGF treatment. The effective cardiovascular antifibrotic and regenerative actions of LGF support its potential in the treatment of hypertension and its complications.

Effects of exercise and L-arginine on ventricular remodeling and oxidative stress

OBJECTIVE

Our aim was to characterize the changes in messenger RNA (mRNA) abundance, protein, and activity levels of the enzymatic antioxidants, superoxide dismutase (SOD), glutathione peroxidase, and catalase by exercise training combined with L-arginine after myocardial infarction (MI).

METHODS

L-Arginine (1 g x kg(-1) x d(-1)) and N(G)-nitro-L-arginine methyl ester (L-NAME; 10 mg x kg(-1) x d(-1)) were administered in drinking water for 8 wk. Sprague-Dawley rats were randomized to the following groups: sham-operated control (Sham); MI sedentary (Sed); MI exercise (Ex); MI sedentary + L-arginine (Sed + LA); MI exercise + L-arginine (Ex + LA); MI sedentary + L-NAME (Sed + L-NAME); and MI exercise + L-NAME (Ex + L-NAME).

RESULTS

The glutathione peroxidase, catalase, and gp91(phox) mRNA levels were comparable among all the groups. The SOD mRNA level was significantly increased in the Ex group (5.43 +/- 0.87) compared with the Sed group (1.74 +/- 0.29), whereas this effect was pronouncedly down-regulated by the L-NAME intervention (2.51 +/- 1.17, P < 0.05). The protein levels of SOD in the Sed and Ex groups were both significantly decreased with the administration of L-NAME. The protein levels of catalase were significantly higher in the Ex and Ex + LA groups than that in the Sed, Sed + LA, and L-NAME-treated groups. The collagen volume fraction was significantly lowered by the exercise and/or L-arginine treatment when compared with the Sed group. Fractional shortening was significantly preserved in the trained groups compared with their corresponding sedentary groups with or without drug treatments. However, the beneficial effect was not further improved by L-arginine treatment.

CONCLUSIONS

Our results suggest that exercise training exerts antioxidative effects and attenuates myocardial fibrosis in the MI rats. These improvements, in turn, alleviate cardiac stiffness and preserve post-MI cardiac function. In addition, L-arginine appears to have no additive effect on cardiac function or expression of enzymatic antioxidants.

Heightened aberrant deposition of hard-wearing elastin in conduit arteries of prehypertensive SHR is associated with increased stiffness and inward remodeling

Elastin is a major component of conduit arteries and a key determinant of vascular viscoelastic properties. Aberrant organization of elastic lamellae has been reported in resistance vessels from spontaneously hypertensive rats (SHR) before the development of hypertension. Hence, we have characterized the content and organization of elastic lamellae in conduit vessels of neonatal SHR in detail, comparing the carotid arteries from 1-wk-old SHR with those from Wistar-Kyoto (WKY) and Sprague Dawley (SD) rats. The general structure and mechanics were studied by pressure myography, and the internal elastic lamina organization was determined by confocal microscopy. Cyanide bromide-insoluble elastin scaffolds were also prepared from 1-mo-old SHR and WKY aortas to assess their weight, amino acid composition, three-dimensional lamellar organization, and mechanical characteristics. Carotid arteries from 1-wk-old SHR exhibited narrower lumen and greater intrinsic stiffness than those from their WKY and SD counterparts. These aberrations were associated with heightened elastin content and with a striking reduction in the size of the fenestrae present in the elastic lamellae. The elastin scaffolds isolated from SHR aortas also exhibited increased relative weight and stiffness, as well as the presence of peculiar trabeculae inside the fenestra that reduced their size. We suggest that the excessive and aberrant elastin deposited in SHR vessels during perinatal development alters their mechanical properties. Such abnormalities are likely to compromise vessel expansion during a critical period of growth and, at later stages, they could compromise hemodynamic function and participate in the development of systemic hypertension.

The nitric oxide/cGMP signaling pathway in pulmonary hypertension

This article briefly reviews the background of endothelium-dependent vasorelaxation, describes the nitric oxide/cGMP/protein kinase pathway and its role in modulating pulmonary vascular tone and remodeling, and describes three approaches that target the nitric oxide/cGMP pathway in the treatment of patients with pulmonary arterial hypertension.