NO Synthase Inhibitor Research Articles

Hyperbaric oxygen produces a nitric oxide synthase-regulated anti-allodynic effect in rats with paclitaxel-induced neuropathic pain

Research has demonstrated that hyperbaric oxygen (HBO2) treatment produced relief of both acute and chronic pain in patients and animal models. However, the mechanism of HBO2 antinociceptive effect is still elusive. Based on our earlier findings that implicate NO in the acute antinociceptive effect of HBO2, the purpose of this study was to ascertain whether HBO2-induced antinociception in a chronic neuropathic pain model is likewise dependent on NO. Neuropathic pain was induced in male Sprague Dawley rats by four injections of paclitaxel (1.0 mg/kg, i.p.). Twenty-four hours after the last paclitaxel injection, rats were treated for one day or four consecutive days with 60-min HBO2 at 3.5 atmospheres absolute (ATA). Two days before HBO2 treatment, some groups of rats were implanted with Alzet® osmotic minipumps that continuously infused a selective inhibitor of neuronal NO synthase (nNOS) into the lateral cerebral ventricle for 7 days. Mechanical and cold allodynia were assessed every other day, using electronic von Frey and acetone assays, respectively. Rats in the paclitaxel control group exhibited a mechanical or cold allodynia that was significantly reversed by one HBO2 treatment for mechanical allodynia and four HBO2 treatments for cold allodynic. In rats treated with the nNOS inhibitor, the effects of HBO2 were nullified in the mechanical allodynia test but unaffected in the cold allodynia test. In summary, these results demonstrate that the antiallodynic effect of HBO2 in two different pain tests is dependent on NO in the CNS.

The role of neuronal nitric oxide and its pathways in the protection and recovery from neurotoxin-induced de novo hypokinetic motor behaviors in the embryonic zebrafish (Danio rerio).

Neuronal nitric oxide (nNO) has been shown to affect motor function in the brain. Specifically, nNO acts in part through regulation of dopamine (DA) release, transporter function, and the elicitation of neuroprotection/neurodegeneration of neurons in conditions such as Parkinson's disease (PD). Recently, the zebrafish has been proposed to be a new model for the study of PD since neurotoxin damage to their nigrostriatal-like neurons exhibit PD-like motor dysfunctions similar to those of mammalian models and human patients. Results from this study demonstrate that treatment of 5 days post fertilization (dpf) fish with a nNO synthase inhibitor as a co-treatment with 6-OHDA facilitates long-term survival and accelerates the recovery from 6-OHDA-induced hypokinesia-like symptoms. These findings are unique in that under conditions of neurotoxin-induced stress, the inhibition of the NO-related S-nitrosylation indirect pathway dramatically facilitates recovery from 6-OHDA treatment but inhibition of the NO-sGC-cGMP direct pathway is essential for survival in 5 dpf treated fish. In conclusion, these results indicate that nNOS and the inhibition of the NO-linked S-nitrosylation pathway plays an important role in antagonizing the protection and recovery of fish from neurotoxin treatment. These data begin to help in the understanding of the role of NO as a neuroprotectant in dopaminergic pathways, particularly those that influence motor dysfunctions.

NO-synthase activity in mitochondria of uterus smooth muscle: identification and biochemical properties.

Information about the catalytic and kinetic properties of mitochondria NO-synthase from uterus smooth muscle is missing currently. According to the data on MitoTracker Orange CM-H2TMRos and 4-аmino-5-methylamino-2',7'-difluorescein, diaminofluorescein-FM (DAF-FM) dye co-localization in uterine smooth muscle cells, presented in this paper, NO can be synthesized in their mitochondria. High activity of NO synthase requires the presence of substrates of respiration, L-arginine, Ca2+ and NADPH. It is established that the dependence of NO production on the concentration of L-arginine has a bell-shaped character with a maximum of 75 μM, and the apparent affinity constant for L-arginine is 28.9 ± 9.1 μM. The dependence of NO production on Ca2+ concentration has a maximum at 100-250 μM; the activation constant for Ca2+ is 44.4 ± 14.5 μM. The inhibitor of Ca2+ transport in mitochondria ruthenium red (RuR), as well as the inhibitor of NO-synthase NG-nitro-L-arginine (NA), reduces NO production. The biosynthesis of NO by mitochondria depends on its energized level: it is stimulated by the addition of respiration substrates, suppressed with specific inhibitors of the electron transport chain (rotenone and antimycin A) and carbonyl-cyanide 3-chlorophenylhydrazone (CCCP) protonophore.

Role of nitric oxide in psychostimulant-induced neurotoxicity.

In recent decades, consumption of psychostimulants has been significantly increased all over the world, while exact mechanisms of neurochemical effects of psychomotor stimulants remained unclear. It is assumed that the neuronal messenger nitric oxide (NO) may be involved in mechanisms of neurotoxicity evoked by psychomotor stimulants. However, possible participation of NO in various pathological states is supported mainly by indirect evidence because of its short half-life in tissues. Aim of this review is to describe the involvement of NO and the contribution of lipid peroxidation (LPO) and acetylcholine (ACH) release in neurotoxic effects of psychostimulant drugs. NO was directly determined in brain structures by electron paramagnetic resonance (EPR). Both NO generation and LPO products as well as release of ACH were increased in brain structures following four injections of amphetamine (AMPH). Pretreatment of rats with the non-selective inhibitor of NO-synthase (NOS) N-nitro-L-arginine or the neuronal NOS inhibitor 7-nitroindazole significantly reduced increase of NO generation as well as the rise of ACH release induced by AMPH. Both NOS inhibitors injected prior to AMPH had no effect on enhanced levels of LPO products. Administration of the noncompetitive NMDA receptor antagonist dizocilpine abolished increase of both NO content and concentration of LPO products induced by of the psychostimulant drug. Dizocilpine also eliminated the influence of AMPH on the ACH release. Moreover, the neurochemical and neurotoxic effects of the psychostimulant drug sydnocarb were compared with those of AMPH. Single injection of AMPH showed a more pronounced increase in NO and TBARS levels than after an equimolar concentration of sydnocarb. The findings demonstrate the crucial role of NO in the development of neurotoxicity elicited by psychostimulants and underline the key role of NOS in AMPH-induced neurotoxicity.

Роль индуцибельной NO-синтазы в развитии церебральной гиперемии после ишемии/реперфузии

This work was aimed to study the iNOS role in the pial arterial vascular tone regulation and tissue perfusion in the post-ischemic time in the first 7 days after ischemia/reperfusion (I/R). Ischemia was induced in anesthetized Wistar rats (n=33) by clamping of both common carotid arteries for 12 min with simultaneous controlled hypotension to 45±3 mm Hg. The diameter changes of pial arteries and arterioles were visialised using in-vivo video microscopy. The responses response to selective iNOS inhibitor aminoguanidine (AG) and non-selective inhibitor of NO-synthases by L-NAME were studied. At the same time tissue perfusion (P) and hematocrit were determined in the same animals. 5 different groups of rats were studeid: intact (control), and 1 hour, 1, 3, or 7 days after ischemia. The maximal (1.6 times) increase in P was observed 1 hour after I/P, and after 1 day it returned to the control level. The tissue hematocrit was increased at 1 hour after the I/R, and peaked on the 3rd day (by 40%). After 7 days the hematocrit remained about 20% higher than in control. In control rats, L-NAME reduced the vessels diameter by 10-14% on average, and AG did not lead to significant changes in the diameter. The AG effect on the vessels was observed only in the time period from 1 to 3 days after I/R. At this time, the effect of AG was similar to that of L-NAME. At 7th day, the pial artery reactions to AG and L-NAME decreased to the control levels. We conclude that the NO-mediated dilation of the pial arteries caused by the iNOS expression plays a prominent role in the cerebral tissue hyperemia in the first 7 days of the post-ischemic period.

Vasorelaxant and antihypertensive effects of Tianshu Capsule on rats: An in vitro and in vivo approach

BackgroundBoth Chuanxiong (Ligusticum chuanxiong Hort) and Tianma (Gastrodia elata Blume) have the effects of vasorelaxation and antihypertension. However, the effects of Tianshu Capsule (TSC, composed of Chuanxiong and Tianma in the mass ratio of 4:1) on antihypertensive activity have not been explored. This study aimed to investigate the eff ;ects of TSC on vascular tension and blood pressure in rats and to explore the underlying mechanisms. MethodsThe vasorelaxant effect of TSC was explored on thoracic aortic rings (both intact endothelium and denuded) preincubated with phenylephrine (Phe) or potassium chloride (KCL). The mechanism was investigated in the presence of antagonists or blockers on aorta isolated from normotensive rats. The in vivo antihypertensive effect was assessed using a tail-cuff method on spontaneously hypertensive rats (SHRs). ResultsTSC (0.125–4 mg/mL) produced a concentration-dependent vasorelaxation on aortic rings preincubated with Phe (1 μM) or KCL (60 mM). Removal of aorta endothelium markedly attenuated the TSC activity. Pretreatment of aortic rings with β-adrenoceptor blocker propranolol (1 μM), muscarinic receptor antagonist atropine (1 μM), cyclooxygenase inhibitor indomethacin (IDO, 1 μM), adenylyl cyclase inhibitor 9-(tetrahydro-2-furanyl)-9H-purine-6-amine (SQ22536, 100 μM), K+ channel blockers 4-aminopyridine(4-AP, 1 mM) or barium chloride(BaCl2, 1 mM) followed by addition of Phe (1 μM) prior to TSC did not influence the TSC-induced relaxation. In contrast, the vasorelaxant effects of TSC were markedly inhibited by the NO synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME, 10 μM), guanylyl cyclase inhibitor 1H- [1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 μM), K+ channel blockers, glibenclamide (100 μM) and clotrimazole (5 mM). Moreover, TSC (2 mg/mL, 4 mg/mL) inhibited CaCl2-induced contractions and caused a concentration-dependent rightward shift of the response curves. Additionally, TSC (2 mg/mL, 4 mg/mL) depressed the constriction caused by Phe (1 μM) in the absence of extracellular Ca2+. Furthermore, TSC (2.15 g/kg) lowered the systolic blood pressure (SBP), with no alteration in heart rate (HR) in SHRs. ConclusionsThese findings demonstrated that TSC induced vasorelaxant effects via both endothelium-dependent and endothelium-independent pathways. The NO/sGC/cGMP pathway, ATP-sensitive K+ channels, Ca2+-activated K+ channels, inhibition of extracellular Ca2+ influx and intracellular Ca2+ release were probably involved in this relaxation. The vasorelaxant effects of TSC may make the greatest contribution to the reduction in high blood pressure.

Vasorelaxant and chemical fingerprint studies of Citrus reticulatae pericarpium extracts

Ethnopharmacological relevanceCitrus reticulatae Pericarpium (Chen pi) was widely used as an important ingredient in the prescription of TCM to treat phlegm fluid retention type hypertension. Since Chen pi is involved in treatment as antihypertensive TCM formula, we have reasonable expectation in believing that it might possess vasorelaxant activity. Aim of the studyThis study is designed to investigate the vasorelaxant effect of Chen pi and to study its pharmacology effects. Materials and methodsThe vasorelaxant effect of water extract of Chen pi (CRW) were evaluated on thoracic aortic rings isolated from Sprague Dawley rats. The fingerprint of Chen pi and the extracts were developed with quantification of hesperidin content by HPTLC. ResultsCRW exhibited the strongest vasorelaxant activity. CRW caused the relaxation of the phenylephrine pre-contracted aortic rings in the presence and absence of endothelium as well as in potassium chloride pre-contracted endothelium-intact aortic ring. The incubation of propranolol (β-adrenergic receptor blocker), atropine (muscarinic receptor blocker), Nω-nitro-L-arginine methyl ester (NO synthase inhibitor), ODQ (sGC inhibitor), indomethacin (COX inhibitor), 4-aminopyridine (KV blocker), barium chloride (Kir blocker), and glibenclamide (KATP blocker) significantly reduced the vasorelaxant effects of CRW. CRW was also found to be active in reducing Ca2+ releases from the sarcoplasmic reticulum and suppressing the voltage-operated calcium channels. ConclusionThe vasorelaxant effect of CRW on rat aorta involves NO/sGC, calcium and potassium channels, muscarinic and β-adrenergic receptors.

Enhanced nitric oxide signaling amplifies vasorelaxation of human colon cancer feed arteries.

Inadequate perfusion of solid cancer tissue results in low local nutrient and oxygen levels and accumulation of acidic waste products. Previous investigations have focused primarily on tumor blood vessel architecture, and we lack information concerning functional differences between arteries that deliver blood to solid cancer tissue versus normal tissue. Here, we use isometric myography to study resistance-sized arteries from human primary colon adenocarcinomas and matched normal colon tissue. Vasocontraction of colon cancer feed arteries in response to endothelin-1 and thromboxane stimulation is attenuated compared with normal colon arteries despite similar wall dimensions and comparable contractions to arginine vasopressin and K+-induced depolarization. Acetylcholine-induced vasorelaxation and endothelial NO synthase expression are increased in colon cancer feed arteries compared with normal colon arteries, whereas vasorelaxation to exogenous NO donors is unaffected. In congruence, the differences in vasorelaxant and vasocontractile function between colon cancer feed arteries and normal colon arteries decrease after NO synthase inhibition. Rhythmic oscillations in vascular tone, known as vasomotion, are of lower amplitude but similar frequency in colon cancer feed arteries compared with normal colon arteries. In conclusion, higher NO synthase expression and elevated NO signaling amplify vasorelaxation and attenuate vasocontraction of human colon cancer feed arteries. We propose that enhanced endothelial function augments tumor perfusion and represents a potential therapeutic target. NEW & NOTEWORTHY Local vascular resistance influences tumor perfusion. Arteries supplying human colonic adenocarcinomas show enhanced vasorelaxation and reduced vasocontraction mainly due to elevated nitric oxide-mediated signaling. Rhythmic oscillations in tone, known as vasomotion, are attenuated in colon cancer feed arteries.

Blood Pressure Changes After Exposures Increasing Angiotensin-Converting Enzyme Activity and After Its Normalization with Dihydroquercetin in Male Wistar Rats.

Changes in BP and HR were assessed after exposures increasing activity of angiotensin-converting enzyme: ionizing radiation, NO synthase inhibitor (L-NAME), and dexamethasone. Effects of dihydroquercetin and angiotensin-converting enzyme inhibitor enalapril on activity of this enzyme, BP, and HR were also evaluated under these exposures. Wistar male rats were subjected to X-ray irradiation in a dose of 2.5 Gy. Angiotensin-converting enzyme activity in the aorta sections was determined by Hip-His-Leu hydrolysis. BP and HR were recorded using a non-invasive tail-cuff method and PowerLab 8/35 software. BP and HR were not altered with the increase in activity of angiotensin-converting enzyme after irradiation. In case of prolonged (7 days) treatment with NO synthase inhibitor and dexamethasone, the increase in enzyme activity was accompanied by elevation of BP and, in the case of NO synthase inhibitor, HR reduction. Dihydroquercetin normalized the enzyme activity and lowered BP, but not to the normal level. Enalapril normalized BP, increased by NO synthase inhibitor solution intake; at the same time, the angiotensinconverting enzyme activity decreased more than 2-fold in comparison with the normal.

Effects of Nitrate and L-Arginine on Content of Nitric Oxide and Activities of Antioxidant Enzymes in Roots of Wheat Seedlings and Their Heat Resistance

Separate and combined effects of nitrate (NaNO3) and L-arginine as potential sources of nitric oxide (NO) on the content of endogenous NO in roots of wheat (Triticum aestivum L.) seedlings and on their heat resistance were studied. Both agents increased the seedling resistance to the damaging heating; the effect was maximal at 20 mM NaNO3 or 5 mM L-arginine. The treatment with L-arginine elevated the NO content in the roots within the first 2 h of the treatment. Nitrate caused a stronger and longer rise in nitric oxide. Activity of nitrate reductase considerably (2–3 times) increased in the roots exposed to nitrate. The augmentation in the nitric oxide level caused by nitrate or L-arginine was prevented by the root pretreatment with an inhibitor of nitrate reductase (sodium tungstate) or an inhibitor of animal NO-synthase—NG-nitro-L-arginine methyl ester (L-NAME). Upon the combined treatment with NaNO3 and L-arginine, the nitrateinduced stimulation of the nitrate reductase activity, NO level in the roots, and seedling heat resistance were less pronounced than after separate application. In the presence of L-NAME, the negative influence of L-arginine on nitrate effects was markedly attenuated. The plant exposure to nitrate or L-arginine increased the activities of antioxidant enzymes (superoxide dismutase, catalase, and guaiacol peroxidase). A mixture of NaNO3, and L-arginine caused weaker effects. It was suggested that nitrate-dependent and arginine-dependent pathways of NO formation are antagonistic to each other in wheat roots.

Role of Noradrenergic Brain Nuclei in the Regulation of Carotid Artery Blood Flow: Pharmacological Evidence from Anesthetized Pigs with Alpha-2 Adrenergic Receptor Modulator Drugs.

Cerebral hypoperfusion and degeneration of the noradrenergic locus coeruleus (LC) occur early in Alzheimer's disease (AD). Cerebral blood vessels are densely innervated by noradrenergic projections from the LC suggesting a functional role for the regulation of cerebral blood flow (CBF). Experimental LC stimulation, however, has provided no clarity as decreases or increases in CBF were reported from different experimental settings and investigators. To find out with pharmacological methods whether endogenously released norepinephrine (NE) increases or decreases carotid artery blood flow (CABF) in anesthetized pigs by investigating the effect of centrally acting alpha-2 adrenergic drugs, which increase (atipamezole) or decrease (xylazine) NE in the brain. CABF was measured by a Doppler-flow probe placed around the left carotid artery in pentobarbital anesthetized young pigs. Neither current antihypertensive drugs nor pharmacological stimulation of dopamine, histamine, serotonin or acetylcholine receptors changed CABF. The alpha-2 adrenergic-receptor agonist xylazine decreased, while the antagonist atipamezole raised CABF. This rise was abolished by a combined treatment with endothelial NO-synthase inhibitor Nω-Nitro-L-arginine methyl ester (L-NAME) and the non-selective β-receptor antagonist propranolol. Propranolol alone did not decrease CABF in contrast to L-NAME but decreased CABF after L-NAME, surprisingly. Pharmacological evidence suggests that NE released in the brain of anesthetized pigs raises CABF involving β-adrenergic mechanisms and nitric oxide. If in awake humans NE released from the LC had vasodilator effects early LC degeneration could be involved in early cerebral hypoperfusion of AD. Moreover, a cerebral adrenergic vascular innervation deficit, possibly resulting from LC degeneration, and systemic endothelial dysfunction together may act synergistically to reduce CBF.

Melatonin and inflammation-Story of a double-edged blade.

Melatonin is an immune modulator that displays both pro- and anti-inflammatory properties. Proinflammatory actions, which are well documented by many studies in isolated cells or leukocyte-derived cell lines, can be assumed to enhance the resistance against pathogens. However, they can be detrimental in autoimmune diseases. Anti-inflammatory actions are of particular medicinal interest, because they are observed in high-grade inflammation such as sepsis, ischemia/reperfusion, and brain injury, and also in low-grade inflammation during aging and in neurodegenerative diseases. The mechanisms contributing to anti-inflammatory effects are manifold and comprise various pathways of secondary signaling. These include numerous antioxidant effects, downregulation of inducible and inhibition of neuronal NO synthases, downregulation of cyclooxygenase-2, inhibition of high-mobility group box-1 signaling and toll-like receptor-4 activation, prevention of inflammasome NLRP3 activation, inhibition of NF-κB activation and upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2). These effects are also reflected by downregulation of proinflammatory and upregulation of anti-inflammatory cytokines. Proinflammatory actions of amyloid-β peptides are reduced by enhancing α-secretase and inhibition of β- and γ-secretases. A particular role in melatonin's actions seems to be associated with the upregulation of sirtuin-1 (SIRT1), which shares various effects known from melatonin and additionally interferes with the signaling by the mechanistic target of rapamycin (mTOR) and Notch, and reduces the expression of the proinflammatory lncRNA-CCL2. The conclusion on a partial mediation by SIRT1 is supported by repeatedly observed inhibitions of melatonin effects by sirtuin inhibitors or knockdown.

PL - 032 Physiological triggers involved in reduced slow myosin expression in disused postural muscle

PL - 032 Physiological triggers involved in reduced slow myosin expression in disused postural muscle

A11877 Effect of D4 Dopamine Receptor on Na +- K+-ATP Activity in Renal Proximal Tubule Cells

Objectives: To investigate the effect of D4 dopamine receptor on Na+-K+-ATPase activity in renal proximal tubule (RPT) cells, the underlying mechanism(s) is also determined in this experiment. Methods: Immortalize RPT cells was used in the study to investigate the effect of D4 dopamine receptor agonist PD168077 on Na+-K+-ATPase activity in RPT cells from Wistar-Kyoto (WKY) rats. The NO production were determined by nitrate reductase method. Results: D4 dopamine receptor agonist PD168077 inhibited Na+- K+-ATPase activity in a concentration- and time-dependent manner in WKY RPT cells. The effect was blocked in the presence of D4 receptor antagonist L745870 (10–6 mol/L) and NO synthase inhibitor L-NAME (10–4 mol/L). PD168077 elevated NO production. Conclusion: D4 dopamine receptor agonist PD168077 inhibits Na+-K+-ATPase activity in RPT cells and NO is involved in the mechanisms.

Сhanges in subcellular distribution of lysosomal cysteine proteinases activity in parenchymatous organs of rats under the action of nitric oxide synthesis modulators

Aim. To study the effect of non-selective inhibitor of NO-synthase N-nitro-L-arginine methyl ester (L-NAME) and substrate of nitric oxide synthesis L-arginine on the activity of cathepsins B, L, H and its subcellular distribution in liver, kidney and lung tissues.Materials and methods. The object of study – male rats Wistar line, the material was the cytoplasmic and lysosomal fraction of homogenates of liver, kidney, lung tissues. A non-selective inhibitor of inducible NO-synthase N-nitro-L-arginine methyl ester (L-NAME) was applied at a dose of 25 mg/kg, the substrate of NO synthesis L-arginine – at a dose of 500 mg/kg. Activity of cathepsins B, L, H was defined separately in the cytoplasmic and lysosomal fractions by spectrofluorometry quantitative determination of the specific substrate cleavage product 7-amido-4-methylcoumarin.Results. Suppression of nitric oxide synthesis by non-selective inhibitor of NO-synthase L-NAME (25 mg/kg, 7 days) in the kidney tissue leads to a decrease in the activity of cathepsins В, L, H in lysosomal fraction with a parallel increase in non-lysosomal activity of cathepsin L, in the liver tissue leads to an increase in lysosomal activity of cathepsin H and a decrease in non-lysosomal activity of cathepsin L. The substrate of nitric oxide synthesis L-arginine (500 mg/kg, 10 days) only causes increased activity of cathepsin L in non-lysosomal fraction of liver tissue, leads to increased lysosomal activity of cathepsin H in kidney tissue, the lung tissue shows a significant increase in the activity of the all studied cathepsins in non-lysosomal fraction, accompanied by an increase in lysosomal activity of cathepsins B and H. The revealed changes are associated with the signs of changes in the ratio of pro-enzyme and active forms of cathepsins.Conclusion. The effects of non-selective inhibitor and substrate of nitric oxide synthesis on the total activity of cathepsins B, L and H in parenchymatous organs and its subcellular distribution are tissue-specific and multidirectional in some cases and are accompanied by signs of changes in the ratio of pro-enzyme and enzymatically active forms mainly due to an increase of pro-enzyme forms.

Protective Effect of Dexamethasone on Lipopolysaccharide-Induced Inhibition of Contractile Function of Isolated Lymphatic Vessels and Nodes.

LPS has an inhibitory effect on contractile activity of bovine mesenteric lymphatic vessels and nodes and causes a pronounced decrease in the tone and phase contractions. The selective inhibitor of inducible NO synthase, 1400W, and cyclooxygenase-2 selective inhibitor, dynastat, significantly attenuated the inhibitory effect of LPS. Dexamethasone interferes with the inhibitory effect of LPS on bovine lymphatic vessels and nodes. It was concluded that LPS stimulates expression of inducible NO synthase and cyclooxygenase-2 in endothelial and smooth muscle cells of lymphatic vessels and nodes. Dexamethasone has a pronounced protective effect on the contractile function of lymphatic vessels and nodes affected by LPS and suppresses the expression of inducible NO synthase and cyclooxygenase-2.

The histone demethylase Jarid1b mediates angiotensin II-induced endothelial dysfunction by controlling the 3'UTR of soluble epoxide hydrolase.

The histone demethylase Jarid1b limits gene expression by removing the active methyl mark from histone3 lysine4 at gene promoter regions. A vascular function of Jarid1b is unknown, but a vasoprotective function to inflammatory and hypertrophic stimuli, like angiotensin II (AngII) could be inferred. This hypothesis was tested using Jarid1b knockout mice and the inhibitor PBIT. Mice or aortic segments were treated with AngII to induce endothelial dysfunction. Aortae from WT and Jarid1b knockout were studied in organ chambers and endothelium-dependent dilator responses to acetylcholine and endothelium-independent responses to DetaNONOate were recorded after pre-constriction with phenylephrine in the presence or absence of the NO-synthase inhibitor nitro-L-arginine. Molecular mechanisms were investigated with chromatin immunoprecipitation, RNA-Seq, RNA-3'-adaptor-ligation, actinomycin D and RNA-immunoprecipitation. Knockout or inhibition of Jarid1b prevented the development of endothelial dysfunction in response to AngII. This effect was not a consequence of altered nitrite oxide availability but accompanied by a loss of the inflammatory response to AngII. As Jarid1b mainly inhibits gene expression, an indirect effect should account for this observation. AngII induced the soluble epoxide hydrolase (sEH), which degrades anti-inflammatory lipids, and thus promotes inflammation. Knockout or inhibition of Jarid1b prevented the AngII-mediated sEH induction. Mechanistically, Jarid1b maintained the length of the 3'untranslated region of the sEH mRNA, thereby increasing its stability and thus sEH protein expression. Loss of Jarid1b activity therefore resulted in sEH mRNA destabilization. Jarid1b contributes to the pro-inflammatory effects of AngII by stabilizing sEH expression. Jarid1b inhibition might be an option for future therapeutics against cardiovascular dysfunction.

Activation of NQO-1 mediates the augmented contractions of isolated arteries due to biased activity of soluble guanylyl cyclase in their smooth muscle.

Earlier studies on isolated arteries demonstrated that the para-quinone thymoquinone, like acute hypoxia, induces augmentation of contractions, depending on biased activity of soluble guanylyl cyclase (sGC), generating inosine-3',5'-cyclic monophosphate (cyclic IMP) rather than guanosine-3',5'-cyclic monophosphate (cyclic GMP). NAD(P)H:quinone oxidoreductase 1 (NQO-1), the enzyme responsible for biotransformation of quinones into hydroquinones, was examined for its involvement in these endothelium-dependent augmentations, establishing a link between the metabolism of quinones by NQO-1 and biased sGC activity. Isolated arteries of Sprague-Dawley rats (aortae and mesenteric arteries) and farm pigs (coronary arteries) were studied for measurement of changes in tension and collected to measure NQO-1 activity or its protein level. β-lapachone, an ortho-quinone and hence substrate of NQO-1, increased the activity of the enzyme and augmented contractions in arteries with endothelium. This augmentation was inhibited by endothelium removal and inhibitors of endothelial NO synthase (eNOS), sGC, or NQO-1; in preparations without endothelium or treated with an eNOS inhibitor, it was restored by the NO donor DETA NONOate and by ITP and cyclic IMP, revealing biased sGC activity as the underlying mechanism, as with thymoquinone. Hydroquinone, the end product of quinone metabolism by NQO-1, augmented contractions depending on sGC activation but in an endothelium-independent manner. In coronary arteries, repeated acute hypoxia caused similar augmentations as those to quinones that were inhibited by the NQO-1 inhibitor dicoumarol. Augmentations of contraction observed with different naturally occurring quinones and with acute hypoxia are initiated by quinone metabolism by NQO-1, in turn interfering with the NO/biased sGC pathway, suggesting a possibly detrimental role of this enzyme in ischemic cardiovascular disorders.

DYNAMICS OF ASYMMETRIC DIMETHYLARGININE AFTER RENAL DENERVATION IN PATIENTS WITH RESISTANT HYPERTENSION

Objective: The recent experimental and clinical studies evidence a potential bidirectional relationship between sympathetic activity and the endogenous circulating NO synthase inhibitor asymmetric dimethylarginine (ADMA). However, the data are controversial. The purpose of our study was to assess the change in ADMA level after renal sympathetic denervation (RSDN) in patients with resistant hypertension (RAH). Design and method: We examined 19 patients (7 males) with verified RAH [mean age – 59 (28–70) years], who underwent the RSDN by standard protocol (Simplicity, Medtronic). ADMA level was measured by immune-enzyme assay (ADMA direct ELISA Kit, Immunodiagnostic AG, Bensheim, Germany, reference values 0.26–0.64 mcmol/l) at baseline before the RSDN (the first patient was enrolled in 2013), 6 and 12 months after the operation (the last patient was examined in 2015). Statistical analysis was carried out using the program SPSS 17.0, the data are presented as median (25%;75%). Results: At baseline ADMA was 0.81 (0.3; 1.98) mcmol/l. The increased values were found in 1 male and 9 females (chi-square = 1.9; p = 0.2) without any gender differences compared to those with normal ADMA level. ADMA level remained unchanged at 6-month follow-up: 0.83 (0.35; 0.94) mcmol/l (p = 0.91). Although it decreased by 12-month follow-up visit – 0.66 (0.23; 0.99) mcmol/l, the changes were non-significant (p = 0.6, repeated measures, one-way ANOVA). Conclusions: Half of RAH patients (53%) demonstrate increased ADMA indicating worse prognosis. Renal denervation failed to decrease ADMA level. However, small sample size and a trend toward improvement of endothelial function deserves further investigation in order to understand who may benefit from the RSDN procedure in the very high risk population with resistant hypertension.

The effects of proton pump inhibitor on hepatic vascular responsiveness and hemodynamics in cirrhotic rats

BackgroundLiver cirrhosis is associated with increased intrahepatic resistance due to hepatic fibrosis and exaggerated vasoconstriction. Recent studies have indicated that proton pump inhibitors (PPIs), in addition to acid suppression, modulate vasoactive substances and vasoresponsiveness. PPIs are frequently prescribed in patients with cirrhosis due to a higher prevalence of peptic ulcers, however other impacts are unknown. MethodsLiver cirrhosis was induced in Sprague–Dawley rats with common bile duct ligation (BDL). On the 29th day after BDL and after hemodynamic measurements, the intrahepatic vascular responsiveness to high concentrations of endothelin-1 (ET-1) was evaluated after preincubation with (1) Krebs solution (vehicle), (2) esomeprazole (30 μM), or (3) esomeprazole plus Nω-nitro l-arginine (NNA, a non-selective NO synthase (NOS) inhibitor, 10−4 M). After perfusion, the hepatic protein expressions of endothelial NOS (eNOS), inducible NOS (iNOS), cyclooxygenase (COX)-1, COX-2, endothelin-1, DDAH-1 (dimethylarginine dimethylaminohydrolase-1, ADMA inhibitor), DDAH-2, ADMA (asymmetrical dimethyl arginine, NOS inhibitor) were evaluated. In the chronic model, the BDL rats received (1) vehicle; or (2) esomeprazole (3.6 mg/kg/day, oral gavage) from the 1st to 28th day after BDL. On the 29th day and after hemodynamic measurements, plasma liver biochemistry and liver fibrosis were evaluated. ResultsEsomeprazole did not affect hepatic ET-1 vasoresponsiveness. The hepatic protein expressions of the aforementioned factors were not significantly different among the groups. There were no significant differences in hemodynamics, liver biochemistry and hepatic fibrosis after chronic esomeprazole administration. ConclusionPPIs did not affect hepatic vasoresponsiveness or the release of vasoactive substances. Furthermore, they did not influence hemodynamics, liver biochemistry or severity of hepatic fibrosis in the cirrhotic rats.