Displaying publications 1 - 20 of 38 in total

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  1. Mechanisms of α-mangostin-induced antinociception in a rodent model
    Sani MH, Taher M, Susanti D, Kek TL, Salleh MZ, Zakaria ZA
    Biol Res Nurs, 2015 Jan;17(1):68-77.
    PMID: 25504952 DOI: 10.1177/1099800414529648
    Elucidate the antinociceptive mechanisms of α-mangostin isolated from Garcinia malaccensis Linn.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/administration & dosage
  2. Effect of Antihypertensive Drug Treatment on Oxidative Stress Markers in Heart of Spontaneously Hypertensive Rat Models
    Yusoff NSN, Mustapha Z, Sharif SET, Govindasamy C, Sirajudeen KNS
    J Environ Pathol Toxicol Oncol, 2017;36(1):43-53.
    PMID: 28605330 DOI: 10.1615/JEnvironPatholToxicolOncol.2017014521
    Oxidative stress has been suggested to play a role in hypertension- and hypertension-induced organ damage. The effect of antihypertensive drug treatments on oxidative stress markers has not been well assessed. Therefore, in this study we investigated the effect of enalapril on oxidative stress markers in hearts of hypertensive rat models such as spontaneously hypertensive rats (SHR) and SHRs administered N-nitro-L-arginine methyl ester (SHR+L-NAME rats). Male rats were divided into four groups: SHRs, SHR+enalapril (SHR-E) rats, SHR+L-NAME rats, SHR+enalapril+L-NAME (SHRE+L-NAME) rats. Rats (SHREs) were administered enalapril (30 mg kg-1 day-1) in drinking water from week 4 to week 28 and L-NAME (25 mg kg-1 day-1) from week 16 to week 28 in drinking water. At the end of 28 weeks, animals were sacrificed, and their hearts were collected for the assessment of oxidative stress markers and histological examination. Enalapril treatment significantly enhanced the total antioxidant status (TAS) (P < 0.001), reduced the oxidized glutathione ratio (GSH : GSSG) (P < 0.001), and reduced to thibarbituric acid reactive substances (TBARS) (P < 0.001) and protein carbonyl content (PCO) (P < 0.001), which thus reduced the oxidative stress in the heart. The fibrosis areas in SHRs and SHR+L-NAME rats were also markedly reduced. These findings suggest that enalapril might play a protective role in hypertension- and hypertension-induced organ damage.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology*
  3. Fulltext Effect of Clonidine (an antihypertensive drug) treatment on oxidative stress markers in the heart of spontaneously hypertensive rats
    Nik Yusoff NS, Mustapha Z, Govindasamy C, Sirajudeen KN
    Oxid Med Cell Longev, 2013;2013:927214.
    PMID: 23766863 DOI: 10.1155/2013/927214
    Hypertension is a risk factor for several cardiovascular diseases and oxidative stress suggested to be involved in the pathophysiology. Antihypertensive drug Clonidine action in ameliorating oxidative stress was not well studied. Therefore, this study investigate the effect of Clonidine on oxidative stress markers and nitric oxide (NO) in SHR and nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME) administered SHR. Male rats were divided into four groups [SHR, SHR+Clonidine (SHR-C), SHR+L-NAME, SHR+Clonidine+L-NAME(SHRC+L-NAME)]. Rats (SHRC) were administered with Clonidine (0.5 mg kg(-1) day(-1)) from 4 weeks to 28 weeks in drinking water and L-NAME (25 mg kg(-1) day(-1)) from 16 weeks to 28 weeks to SHRC+L-NAME. Systolic blood pressure (SBP) was measured. At the end of 28 weeks, all rats were sacrificed and in their heart homogenate, oxidative stress parameters and NO was assessed. Clonidine treatment significantly enhanced the total antioxidant status (TAS) (P < 0.001) and reduced the thibarbituric acid reactive substances (TBARS) (P < 0.001) and protein carbonyl content (PCO) (P < 0.05). These data suggest that oxidative stress is involved in the hypertensive organ damage and Clonidine not only lowers the SBP but also ameliorated the oxidative stress in the heart of SHR and SHR+L-NAME.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/administration & dosage; NG-Nitroarginine Methyl Ester/pharmacology; NG-Nitroarginine Methyl Ester/therapeutic use
  4. Antihypertensive activity and vascular reactivity mechanisms of Vitex pubescens leaf extracts in spontaneously hypertensive rats
    Al-Akwaa AA, Asmawi MZ, Dewa A, Mahmud R
    Heliyon, 2020 Jul;6(7):e04588.
    PMID: 32775735 DOI: 10.1016/j.heliyon.2020.e04588
    Background: Vitex pubescens has been used traditionally in hypertension treatment but not yet scientifically assessed. The objective of the study is to investigate the antihypertensive and vasorelaxant activities of V. pubescens, study its underlying pharmacological mechanisms, and identify the relevant vasoactive compounds.

    Methods: Successive extractions of V. pubescens leaf were carried out to produce petroleum ether (VPPE), chloroform (VPCE), methanol (VPME), and water (VPWE) extracts. Spontaneously hypertensive rats (SHRs) received a daily oral administration of the extracts (500 mg/kg/day; n = 6) or verapamil (15 mg/kg/day; n = 6) for 2 weeks, while the systolic and diastolic blood pressures were measured using non-invasive tail-cuff method. Vasorelaxation assays of the extracts were later conducted using phenylephrine (PE, 1 μM) pre-contracted aortic ring preparation. Mechanisms of vasorelaxation by the most potent fraction were studied using vasorelaxation assays with selected blockers/inhibitors. GC-MS was conducted to determine the active compounds.

    Results: VPPE elicited the most significant diminution in systolic and diastolic blood pressure of treated SHRs and produced the most significant vasorelaxation in the aortic rings. Vasorelaxant effects of F2-VPPE were significantly reduced in endothelium-denuded aortic rings by glibenclamide (1 μM), whereas calcium chloride and PE-induced contractions were significantly suppressed. Endothelium removal of the aortic rings or incubation with indomethacin (10 μM), atropine (1 μM), methylene blue (10 μM), propranolol (1μM) and L-NAME (10 μM) did not significantly alter F2-VPPE-induced vasorelaxation. Seven compounds were identified using GC-MS, including spathulenol.

    Conclusion: F2-VPPE exerted its endothelium-independent vasorelaxation by inhibition of vascular smooth muscle contraction induced by extracellular Ca+2 influx through trans-membrane Ca+2 channels and/or Ca+2 release from intracellular stores, and by activation of KATP channels. The vasorelaxation effects of V. pubescens could be mediated by the compound, spathulenol.

    Matched MeSH terms: NG-Nitroarginine Methyl Ester
  5. Fulltext Central Antinociceptive and Mechanism of Action of Pereskia bleo Kunth Leaves Crude Extract, Fractions, and Isolated Compounds
    Guilhon CC, Abdul Wahab IR, Boylan F, Fernandes PD
    Evid Based Complement Alternat Med, 2015;2015:915927.
    PMID: 26273315 DOI: 10.1155/2015/915927
    Pereskia bleo (Kunth) DC. (Cactaceae) is a plant commonly used in popular medicine in Malaysia. In this work, we evaluate the antinociceptive effect of P. bleo leaf extracts and isolated compounds in central antinociceptive model. Ethanol extract (E), hexane (H), ethyl acetate (EA), or butanol (B) fractions (30, 50, or 100 mg/kg, p.o.), sitosterol (from hexane) and vitexin (from ethyl acetate), were administered to mice. Antinociceptive effect was evaluated in the hot plate and capsaicin- or glutamate-induced licking models. Morphine (1 mg/kg, p.o.) was used as reference drug. Naloxone (1 mg/kg, i.p.), atropine (1 mg/kg, i.p.), and L-nitro arginine methyl ester (L-NAME, 3 mg/kg, i.p.) were administered 30 min earlier (100 mg/kg, p.o.) in order to evaluate the mechanism of the antinociceptive action. Higher dose of B developed an effect significantly superior to morphine-treated group. Naloxone prevented the antinociceptive effect of all fractions. L-NAME demonstrated effect against E, EA, and B. In all fractions, sitosterol and vitexin reduced the licking time after capsaicin injection. Glutamate-induced licking response was blocked by H, EA, and B. Our results indicate that Pereskia bleo fractions, sitosterol and vitexin, possessed a central antinociceptive effect. Part of this effect is mediated by opioid receptors and nitrergic pathway.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester
  6. Fulltext Antinociceptive Activity of Methanol Extract of Muntingia calabura Leaves and the Mechanisms of Action Involved
    Sani MH, Zakaria ZA, Balan T, Teh LK, Salleh MZ
    Evid Based Complement Alternat Med, 2012;2012:890361.
    PMID: 22611437 DOI: 10.1155/2012/890361
    Muntingia calabura L. (family Elaeocarpaceae) has been traditionally used to relieve various pain-related ailments. The present study aimed to determine the antinociceptive activity of methanol extract of M. calabura leaves (MEMC) and to elucidate the possible mechanism of antinociception involved. The in vivo chemicals (acetic acid-induced abdominal constriction and formalin-, capsaicin-, glutamate-, serotonin-induced paw licking test) and thermal (hot plate test) models of nociception were used to evaluate the extract antinociceptive activity. The extract (100, 250, and 500 mg/kg) was administered orally 60 min prior to subjection to the respective test. The results obtained demonstrated that MEMC produced significant (P < 0.05) antinociceptive response in all the chemical- and thermal-induced nociception models, which was reversed after pretreatment with 5 mg/kg naloxone, a non-selective opioid antagonist. Furthermore, pretreatment with L-arginine (a nitric oxide (NO) donor), N(G)-nitro-L-arginine methyl esters (L-NAME; an inhibitor of NO synthase (NOS)), methylene blue (MB; an inhibitor of cyclic-guanosine monophosphate (cGMP) pathway), or their combination also caused significant (P < 0.05) change in the intensity of the MEMC antinociception. In conclusion, the MEMC antinociceptive activity involves activation of the peripheral and central mechanisms, and modulation via, partly, the opioid receptors and NO/cGMP pathway.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester
  7. Fulltext Cucurbitacin L 2-O-β-Glucoside Demonstrates Apoptogenesis in Colon Adenocarcinoma Cells (HT-29): Involvement of Reactive Oxygen and Nitrogen Species Regulation
    Abdelwahab SI, Hassan LE, Abdul Majid AM, Yagi SM, Mohan S, Elhassan Taha MM, et al.
    Evid Based Complement Alternat Med, 2012;2012:490136.
    PMID: 22685485 DOI: 10.1155/2012/490136
    Emerging evidence suggests that reactive oxygen (ROS) and nitrogen (RNS) species can contribute to diverse signalling pathways of inflammatory and tumour cells. Cucurbitacins are a group of highly oxygenated triterpenes. Many plants used in folk medicine to treat cancer have been found to contain cucurbitacins displaying potentially important anti-inflammatory actions. The current study was designed to investigate the anti-ROS and -RNS effects of cucurbitacin L 2-O-β-glucoside (CLG) and the role of these signaling factors in the apoptogenic effects of CLG on human colon cancer cells (HT-29). This natural cucurbitacin was isolated purely from Citrullus lanatus var. citroides (Cucurbitaceae). The results revealed that CLG was cytotoxic to HT-29. CLG increased significantly (P < 0.05) RNA and protein levels of caspase-3 in HT-29 cells when verified using a colorimetric assay and realtime qPCR, respectively. The results showed that lipopolysaccharide/interferon-gamma (LPS/INF-γ) increased nitrous oxide (NO) production inR AW264.7macrophages, whereas N(G)-nitro-L-argininemethyl ester (L-NAME) and CLG curtailed it. This compound did not reveal any cytotoxicity on RAW264.7 macrophages and human normal liver cells (WRL-68) when tested using the MTT assay. Findings of ferric reducing antioxidant power (FRAP) and oxygen radical absorption capacity (ORAC) assays demonstrate the antioxidant properties of CLG. The apoptogenic property of CLG on HT-29 cells is thus related to inhibition of reactive nitrogen and oxygen reactive species and the triggering of caspase-3-regulated apoptosis.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester
  8. Fulltext Effect of Cymbopogon citratus and Citral on Vascular Smooth Muscle of the Isolated Thoracic Rat Aorta
    Devi RC, Sim SM, Ismail R
    Evid Based Complement Alternat Med, 2012;2012:539475.
    PMID: 22675383 DOI: 10.1155/2012/539475
    Cymbopogon citratus has been shown to have antioxidant, antimicrobial, antispasmodic and chemo-protective properties. Citral, is the major constituent of C. citratus. This study investigated the effects of methanolic extracts of leaves (LE), stems (SE), and roots (RE) of C. citratus and citral on vascular smooth muscle and explored their possible mechanisms of action. The experiment was conducted using isolated tissue preparations, where citral, LE, SE, and RE were added separately into a tissue bath that contained aortic rings, which were pre-contracted with phenylephrine (PE). Citral, LE, and RE exhibited a dose-dependent relaxant effect on the PE-induced contractions. Citral appeared to partially act via NO as its vasorelaxant effect was attenuated by L-NAME. However, the effect of LE may involve prostacyclin as indomethacin reversed the relaxant effect of LE on the PE-induced contraction. Furthermore, citral, LE, and RE abolished the restoration of PE-induced contraction caused by the addition of increasing doses of calcium in both endothelium intact and denuded rings. These findings suggest that the relaxation effect of citral, LE, and RE is endothelium-independent and may be mainly by affecting the intracellular concentration of calcium. Citral may partially act through the NO pathway while a vasodilator prostaglandin may mediate the effect of LE.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester
  9. Fulltext Effect of Aqueous and Ethyl Acetate Fractions of Ziziphus jujuba Mill Extract on Cardiovascular Responses in Hypertensive Rats
    Mohebbati R, Kamkar-Del Y, Shafei MN
    Malays J Med Sci, 2020 May;27(3):43-52.
    PMID: 32684805 DOI: 10.21315/mjms2020.27.3.5
    Background: Ziziphus jujuba Mill (ZJ) is a plant with anti-hypertensive property. In this regard, the present study investigated the effect of aqueous and ethyl acetate fractions of ZJ extract on acute hypertension (HTN) induced by nitro-L-arginine methyl ester (L-NAME).

    Methods: The current study was carried on 49 hypertensive rats divided into seven groups, including i) control; ii) L-NAME (10 mg/kg); iii) sodium nitroprusside (SNP) (50 μg/kg) plus L-NAME; iv and v) aqueous fraction of ZJ (150 mg/kg and 300 mg/kg) plus L-NAME; vi) and vii) ethyl acetate fractions of ZJ (150 mg/kg and 300 mg/kg) plus L-NAME. The rats were orally treated with both fractions for four weeks and received intravenous L-NAME on the 28th day. The mean arterial pressure (MAP), systolic blood pressure (SBP) and heart rate (HR) of the rats were recorded then maximal changes (Δ) of MAP, SBP and HR were calculated and compared with changes of control and L-NAME.

    Results: According to the obtained results of the present study, it was shown that the administration of L-NAME significantly increased ΔMAP, ΔSBP and ΔHR, and these effects were significantly attenuated by administration of SNP. The pre-treatment with both doses (150 mg/kg and 300 mg/kg) of aqueous and ethyl acetate fractions could significantly reduce cardiovascular responses induced by L-NAME that comparable with SNP. However, a lower dose of aqueous fractions and higher dose of ethyl acetate fractions were reported with stronger effects.

    Conclusion: The results of the current study showed that both the aqueous and ethyl acetate fractions of ZJ through the effect on nitric oxide system can prevent the development of HTN induced by L-NAME.

    Matched MeSH terms: NG-Nitroarginine Methyl Ester
  10. Inhibition of L-NAME-induced hypertension by combined treatment with apocynin and catalase: the role of Nox 4 expression
    Chia TY, Murugaiyah V, Khan NA, Sattar MA, Abdulla MH, Johns EJ, et al.
    Physiol Res, 2021 03 17;70(1):13-26.
    PMID: 33728924
    Reactive oxygen species (ROS) such as superoxide (O2-) generated by NAD(P)H oxidases have emerged as important molecules in blood pressure regulation. This study investigated the effect of apocynin and catalase on blood pressure and renal haemodynamic and excretory function in an L-NAME induced hypertension model. Forty Male Wistar-Kyoto (WKY) rats (n=8 per group) were treated with either: vehicle (WKY-C); L-NAME (WKY-L, 15 mg/kg/day in drinking fluid); WKY-L given apocynin to block NAD(P)H oxidase (WKY-LApo, 73 mg/kg/day in drinking water.); WKY-L given catalase to enhance ROS scavenging (WKY-LCat, 10000 U/kg/day i.p.); and WKY-L receiving apocynin plus catalase (WKY-LApoCat) daily for 14 days. L-NAME elevated systolic blood pressure (SBP), 116+/-1 to 181±4 mmHg, reduced creatinine clearance, 1.69+/-0.26 to 0.97+/-0.05 ml/min/kg and fractional sodium excretion, 0.84+/-0.09 to 0.55+/-0.09 % at day 14. Concomitantly, plasma malondialdehyde (MDA) increased six fold, while plasma total superoxide dismutase (T-SOD), plasma nitric oxide (NO) and plasma total antioxidant capacity (T-AOC) were decreased by 60-70 % and Nox 4 mRNA expression was increased 2-fold. Treatment with apocynin and catalase attenuated the increase in SBP and improved renal function, enhanced antioxidative stress capacity and reduced the magnitude of Nox4 mRNAs expression in the L-NAME treated rats. This study demonstrated that apocynin and catalase offset the development of L-NAME induced hypertension, renal dysfunction and reduced oxidative stress status, possibly contributed by a reduction in Nox4 expression during NOS inhibition. These findings would suggest that antioxidant compounds such as apocynin and catalase have potential in treating cardiovascular diseases.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/toxicity*
  11. The effects of tempol on renal function and hemodynamics in cyclosporine-induced renal insufficiency rats
    Chia TY, Sattar MA, Abdulla MH, Rathore HA, Ahmad Fu, Kaur G, et al.
    Ren Fail, 2013 Aug;35(7):978-88.
    PMID: 23822648 DOI: 10.3109/0886022X.2013.809563
    This study investigated the effects of tempol, a superoxide dismutase (SOD) mimetic and L-NAME, a nitric oxide (NO) synthase inhibitor on the renal function and hemodynamics in cyclosporine A (CsA) induced renal insufficiency rats. Male Sprague-Dawley rats were treated with either vehicle (C), tempol (T, 1 mmol/L in drinking fluid), L-NAME (L, 1 mmol/L in drinking fluid), CsA (Cs, 25 mg/kg/day via gavage), CsA plus tempol (TCs), CsA plus L-NAME (LCs) or CsA plus a combination of tempol and L-NAME (TLCs) for 21 consecutive days. At the end of treatment regimen, the renal responses to noradrenaline (NA), phenylephrine (PE), methoxamine and angiotensin II (Ang II) were determined. Cs and LCs rats had lower creatinine clearance (0.7 ± 0.1 and 0.6 ± 0.5 vs. 1.3 ± 0.2 mL/min/kg) and fractional excretion of sodium (0.12 ± 0.02 and 0.17 ± 0.01 vs. 0.67 ± 0.04%) but higher systolic blood pressure (145 ± 2 and 178 ± 4 vs. 116 ± 2) compared to the control (all p 
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/administration & dosage; NG-Nitroarginine Methyl Ester/metabolism
  12. Modulation of the Nitrergic Pathway via Activation of PPAR-γ Contributes to the Neuroprotective Effect of Pioglitazone Against Streptozotocin-Induced Memory Dysfunction
    Prakash A, Kumar A, Ming LC, Mani V, Majeed AB
    J Mol Neurosci, 2015 Jul;56(3):739-50.
    PMID: 25854775 DOI: 10.1007/s12031-015-0508-7
    Alzheimer's disease (AD) is a neurodegenerative disease characterized by impaired memory function and oxidative damage. NO is a major signaling molecule produced in the central nervous system to modulate neurological activity through modulating nitric oxide synthase. Recently, PPAR-γ agonists have shown neuroprotective effects in neurodegenerative disorders. However, there have been only a few studies identifying mechanisms through which cognitive benefits may be exerted. The present study was designed to investigate the possible nitric oxide mechanism in the protective effect of pioglitazone against streptozotocin (STZ)-induced memory dysfunction. Wistar rats were intracerebroventricularly (ICV) injected with STZ. Then rats were treated with pioglitazone, NO modulators [L-arginine and nitro-L-arginine methyl ester (L-NAME)] for 21 days. Behavioral alterations were assessed in between the study period. Animals were sacrificed immediately after behavioral session, and mito-oxidative parameters, TNF-α, IL-6, and caspase-3 activity were measured. STZ-treated rats showed a memory deficit and significantly increased in mito-oxidative damage and inflammatory mediators and apoptosis in the hippocampus. Chronic treatment of pioglitazone significantly improved memory retention and attenuated mito-oxidative damage parameters, inflammatory markers, and apoptosis in STZ-treated rats. However, L-arginine pretreatment with lower dose of pioglitazone has not produced any protective effect as compared to per se. Furthermore, pretreatment of L-NAME significantly potentiated its protective effect, which indicates the involvement of nitric oxide for activation of PPAR-γ action. These results demonstrate that pioglitazone offers protection against STZ-induced memory dysfunction possibly due to its antioxidant, anti-inflammatory, and anti-apoptotic action mediating nitric oxide pathways and, therefore, could have a therapeutic potential in AD.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology; NG-Nitroarginine Methyl Ester/therapeutic use
  13. Fulltext Effect of the antihypertensive drug enalapril on oxidative stress markers and antioxidant enzymes in kidney of spontaneously hypertensive rat
    Chandran G, Sirajudeen KN, Yusoff NS, Swamy M, Samarendra MS
    Oxid Med Cell Longev, 2014;2014:608512.
    PMID: 25254079 DOI: 10.1155/2014/608512
    Oxidative stress has been suggested to play a role in hypertension and hypertension induced organ damage. This study examined the effect of enalapril, an antihypertensive drug, on oxidative stress markers and antioxidant enzymes in kidney of spontaneously hypertensive rat (SHR) and Nω -nitro-L-arginine methyl ester (L-NAME) administered SHR. Male rats were divided into four groups (SHR, SHR+enalapril, SHR+L-NAME, and SHR+enalapril+L-NAME). Enalapril (30 mg kg(-1) day(-1)) was administered from week 4 to week 28 and L-NAME (25 mg kg(-1) day(-1)) was administered from week 16 to week 28 in drinking water. Systolic blood pressure (SBP) was measured during the experimental period. At the end of experimental periods, rats were sacrificed; urine, blood, and kidneys were collected for the assessment of creatinine clearance, total protein, total antioxidant status (TAS), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and catalase (CAT), as well as histopathological examination. Enalapril treatment significantly enhanced the renal TAS level (P < 0.001) and SOD activity (P < 0.001), reduced the TBARS levels (P < 0.001), and also prevented the renal dysfunction and histopathological changes. The results indicate that, besides its hypotensive and renoprotective effects, enalapril treatment also diminishes oxidative stress in the kidneys of both the SHR and SHR+L-NAME groups.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
  14. Exploring the mechanism of endothelial involvement in acidosis-induced vasodilatation of aortic tissues from normal and diabetic rats
    Yeo JL, Tan BT, Achike FI
    Eur J Pharmacol, 2010 Sep 10;642(1-3):99-106.
    PMID: 20553918 DOI: 10.1016/j.ejphar.2010.05.040
    Acidosis modulates physiologic and pathophysiologic processes but the mechanism of acidotic vasodilatation remains unclear. We therefore explored this in aortic rings from normal and streptozotocin-induced diabetic Sprague-Dawley rats. Phenylephrine (PE)-induced contraction in endothelium-intact and -denuded rings were recorded under normal and acidotic pH with or without drug probes. Acidosis exerted a relaxant effect in endothelium-intact and -denuded euglycaemic and diabetic tissues. l-NAME or methylene blue partially inhibited acidotic relaxation in these endothelium-intact but not the -denuded tissues, with greater inhibition in the diabetic tissues, indicating that acidosis induces relaxation by endothelium-dependent and -independent mechanisms, the former being EDNO-cGMP mediated. Indomethacin had no effect on the tissues, indicating that cyclooxygenase products are neither involved in acidosis-induced vasodilatation nor in the modulation of phenylephrine-contraction. In euglycaemic tissues under normal pH, no K(+) channel blocker altered phenylephrine-contraction, but all (except glibenclamide) enhanced diabetic tissue contraction, indicating that normally, these channels (K(ir), K(V), BK(Ca), K(ATP)) do not modulate phenylephrine-contraction, but they (except K(ATP)) are expressed in diabetes where they attenuate phenylephine-induced contraction and modulate acidosis. Only the K(ir) channel modulates acidotic relaxation in euglycaemic tissues. Only tetraethylammonium and iberiotoxin enhanced phenylephrine-induced contraction in endothelium-denuded diabetic tissues indicating that BK(Ca) attenuates phenylephrine-contraction and that acidotic relaxation in this condition is modulated by a tetraethylammonium-sensitive mechanism. In conclusion, acidosis causes vasodilatation in normal and diabetic tissues via endothelium-dependent and -independent mechanisms differentially modulated by a combination of a NO-cGMP process and K(+) channels, some of which are dormant in the normal state but activated in diabetes mellitus.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
  15. Baicalein impairs vascular tone in normal rat aortas: role of superoxide anions
    Machha A, Achike FI, Mohd MA, Mustafa MR
    Eur J Pharmacol, 2007 Jun 22;565(1-3):144-50.
    PMID: 17442302
    Acute exposure to the flavonoid baicalein inhibited endothelium-dependent relaxation in physiological arteries, although the mechanisms are not fully understood. We investigated the effect of baicalein on vascular tone in Wistar-Kyoto (WKY) rat isolated aortic rings in the presence and absence of oxidative stress to further determine the underlying mechanisms. Exposure to baicalein (10 microM) completely abolished endothelium-dependent relaxation induced by acetylcholine and attenuated significantly the endothelium-independent relaxation induced by sodium nitroprusside. Baicalein, similar to Nomega-nitro-L-arginine methyl ester (L-NAME, 10 microM), potentiated significantly the contractile response of aortic rings to alpha1-adrenoceptor agonist phenylephrine. In the presence of L-NAME the baicalein effect on phenylphrine contraction or acetylcholine relaxation was unaltered, suggesting that these effects of baicalein are (like L-NAME effect) endothelial nitric oxide synthase (eNOS)/endothelium-derived nitric oxide-dependent. Inhibition of cyclooxygenase activity with indomethacin (10 microM) or scavenging of superoxide anions with superoxide dismutase (150 units/ml), but not scavenging of hydrogen peroxide with catalase (800 units/ml), enhanced significantly by an essentially similar extent the relaxation to acetylcholine in baicalein-pretreated aortic rings. Relaxant effect to acetylcholine was significantly attenuated in control aortic rings, but was completely abolished in baicalein-pretreated aortic rings in the presence of reduced form of beta-nicotinamide adenine di-nucleotide (beta-NADH, 300 microM). Baicalein blocked beta-NADH (300 microM)-induced transient contractions, suggesting that baicalein may have inhibited activity of NADH/NADPH-oxidase. Baicalein did not alter the failure of acetylcholine to induce relaxation in the presence of pyrogallol (300 microM). In summary, acute exposure to baicalein impairs eNOS/endothelium-derived nitric oxide-mediated vascular tone in rat aortas through the inhibition of endothelium-derived nitric oxide bioavailability coupled to reduced bioactivity of endothelium-derived nitric oxide and to cyclooxygenase-mediated release of superoxide anions.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
  16. The effects of L-arginine, D-arginine, L-name and methylene blue on channa striatus-induced peripheral antinociception in mice
    Zakaria ZA, Sulaiman MR, Somchit MN, Jais AM, Ali DI
    J Pharm Pharm Sci, 2005;8(2):199-206.
    PMID: 16124931
    To determine the involvement of nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway in aqueous supernatant of haruan (Channa striatus) fillet (ASH) antinociception using the acetic acid-induced abdominal constriction test.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology*
  17. Vasorelaxant effect of sinensetin via the NO/sGC/cGMP pathway and potassium and calcium channels
    Yam MF, Tan CS, Shibao R
    Hypertens Res, 2018 Oct;41(10):787-797.
    PMID: 30111856 DOI: 10.1038/s41440-018-0083-8
    Orthosiphon stamineus Benth. (Lambiaceae) is an important traditional plant for the treatment of hypertension. Previous studies have demonstrated that the sinensetin content in O. stamineus is correlated with its vasorelaxant activity. However, there is still very little information regarding the vasorelaxant effect of sinensetin due to a lack of scientific studies. Therefore, the present study was designed to investigate the underlying mechanism of action of sinensetin in vasorelaxation using an in vitro precontraction aortic ring assay. The changes in the tension of the aortic ring preparations were recorded using a force-displacement transducer and the PowerLab system. The mechanisms of the vasorelaxant effect of sinensetin were determined in the presence of antagonists. Sinensetin caused relaxation of the aortic ring precontracted with PE in the presence and absence of the endothelium and with potassium chloride in endothelium-intact aortic rings. In the presence of Nω-nitro-L-arginine methyl ester (nitric oxide synthase inhibitor), methylene blue (cyclic guanosine monophosphate lowering agent), ODQ (selective soluble guanylate cyclase inhibitor), indomethacin (a nonselective cyclooxygenase inhibitor), tetraethylammonium (nonselective calcium activator K+ channel blocker), 4-aminopyridine (voltage-dependent K+ channel blocker), barium chloride (inwardly rectifying Kir channel blocker), glibenclamide (nonspecific ATP-sensitive K+ channel blocker), atropine (muscarinic receptor blocker), or propranolol (β-adrenergic receptor blocker), the relaxation stimulated by sinensetin was significantly reduced. Sinensetin was also active in reducing Ca2+ release from the sarcoplasmic reticulum (via IP3R) and in blocking calcium channels (VOCC). The present study demonstrates the vasorelaxant effect of sinensetin, which involves the NO/sGC/cGMP and indomethacin pathways, calcium and potassium channels, and muscarinic and beta-adrenergic receptors.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
  18. Vasodilator effect of Phlomis bracteosa constituents is mediated through dual endothelium-dependent and endothelium-independent pathways
    Khan AU, Ullah R, Khan A, Mustafa MR, Hussain J, Murugan DD, et al.
    Clin Exp Hypertens, 2012;34(2):132-9.
    PMID: 21967029 DOI: 10.3109/10641963.2011.601383
    This study describes the vasorelaxant potential of some pure compounds isolated from Phlomis bracteosa L. marrubiin, phlomeoic acid, and two new constituents labeled as RA and RB. In rat thoracic aortic rings denuded of endothelium, marrubiin, phlomeoic acid, RA, and RB caused relaxation of high K(+) (80 mM) and phenylephrine (1 μM)-induced contractions at the concentration range of 1.0-1000 μg/mL. Marrubiin, phlomeoic acid, RA, and RB concentration dependently (3.0-10 μg/mL) shifted the Ca(++) curves to the right obtained in Ca(++)-free medium. The vasodilator effect of marrubiin, phlomeoic acid, RA, and RB was partially blocked by N(ω)-nitro-L-arginine methyl ester in endothelium-intact aorta preparations. These results reveal that P. bracteosa constituents: marrubiin, phlomeoic acid, RA, and RB exhibit vasodilator action occurred via a combination of endothelium-independent Ca(++) antagonism and endothelium-dependent N(ω)-nitro-L-arginine methyl ester-sensitive nitric oxide-modulating mechanism.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
  19. Nitric oxide participates in IFN-gamma-induced HUVECs hyperpermeability
    Ng CT, Fong LY, Low YY, Ban J, Hakim MN, Ahmad Z
    Physiol Res, 2016 12 13;65(6):1053-1058.
    PMID: 27539106
    The endothelial barrier function is tightly controlled by a broad range of signaling cascades including nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway. It has been proposed that disturbances in NO and cGMP production could interfere with proper endothelial barrier function. In this study, we assessed the effect of interferon-gamma (IFN-gamma), a pro-inflammatory cytokine, on NO and cGMP levels and examined the mechanisms by which NO and cGMP regulate the IFN-gamma-mediated HUVECs hyperpermeability. The flux of fluorescein isothiocyanate-labeled dextran across cell monolayers was used to study the permeability of endothelial cells. Here, we found that IFN-gamma significantly attenuated basal NO concentration and the increased NO levels supplied by a NO donor, sodium nitroprusside (SNP). Besides, application of IFN-gamma also significantly attenuated both the basal cGMP concentration and the increased cGMP production donated by a cell permeable cGMP analogue, 8-bromo-cyclic GMP (8-Br-cGMP). In addition, exposure of the cell monolayer to IFN-gamma significantly increased HUVECs basal permeability. However, L-NAME pretreatment did not suppress IFN-gamma-induced HUVECs hyperpermeability. L-NAME pretreatment followed by SNP or SNP pretreatment partially reduced IFN-gamma-induced HUVECs hyperpermeability. Pretreatment with a guanylate cyclase inhibitor, 6-anilino-5,8-quinolinedione (LY83583), led to a further increase in IFN-gamma-induced HUVECs hyperpermeability. The findings suggest that the mechanism underlying IFN-gamma-induced increased HUVECs permeability is partly related to the inhibition of NO production.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
  20. Fulltext A Pharmacological Examination of the Cardiovascular Effects of Malayan Krait (Bungarus candidus) Venoms
    Chaisakul J, Rusmili MR, Hodgson WC, Hatthachote P, Suwan K, Inchan A, et al.
    Toxins (Basel), 2017 03 29;9(4).
    PMID: 28353659 DOI: 10.3390/toxins9040122
    Cardiovascular effects (e.g., tachycardia, hypo- and/or hypertension) are often clinical outcomes of snake envenoming. Malayan krait (Bungarus candidus) envenoming has been reported to cause cardiovascular effects that may be related to abnormalities in parasympathetic activity. However, the exact mechanism for this effect has yet to be determined. In the present study, we investigated thein vivoandin vitrocardiovascular effects ofB. candidusvenoms from Southern (BC-S) and Northeastern (BC-NE) Thailand. SDS-PAGE analysis of venoms showed some differences in the protein profile of the venoms.B. candidusvenoms (50 µg/kg-100 µg/kg, i.v.) caused dose-dependent hypotension in anaesthetised rats. The highest dose caused sudden hypotension (phase I) followed by a return of mean arterial pressure to baseline levels and a decrease in heart rate with transient hypertension (phase II) prior to a small decrease in blood pressure (phase III). Prior administration of monovalent antivenom significantly attenuated the hypotension induced by venoms (100 µg/kg, i.v.). The sudden hypotensive effect of BC-NE venom was abolished by prior administration of hexamethonium (10 mg/kg, i.v.) or atropine (5 mg/kg, i.v.). BC-S and BC-NE venoms (0.1 µg/kg-100 µg/ml) induced concentration-dependent relaxation (EC50= 8 ± 1 and 13 ± 3 µg/mL, respectively) in endothelium-intact aorta. The concentration-response curves were markedly shifted to the right by pre-incubation with L-NAME (0.2 mM), or removal of the endothelium, suggesting that endothelium-derived nitric oxide (NO) is likely to be responsible for venom-induced aortic relaxation. Our data indicate that the cardiovascular effects caused byB. candidusvenoms may be due to a combination of vascular mediators (i.e., NO) and autonomic adaptation via nicotinic and muscarinic acetylcholine receptors.
    Matched MeSH terms: NG-Nitroarginine Methyl Ester/pharmacology
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