Displaying publications 1 - 20 of 37 in total

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  1. Chiew GS
    Med J Malaysia, 1979 Dec;34(2):187-92.
    PMID: 232900
    Matched MeSH terms: Cyclic GMP/pharmacology*
  2. Zakaria ZA, Sulaiman MR, Jais AM, Somchit MN, Jayaraman KV, Balakhrisnan G, et al.
    Fundam Clin Pharmacol, 2006 Aug;20(4):365-72.
    PMID: 16867020
    The present study was carried out to investigate on the possible involvement of L-arginine/nitric oxide/cyclic guanosine monophosphate (L-arginine/NO/cGMP) pathway in the aqueous extract of Muntingia calabura (AEMC) leaves antinociception in mice assessed by abdominal constriction test. The AEMC, obtained by soaking the dried leaves in distilled water (DH(2)O) (1 : 2; w/v) for 24 h, was prepared in concentrations of 10%, 50% and 100% that were approximately equivalent to doses of 27, 135 and 270 mg/kg, and administered subcutaneously (s.c.) 5 min after pre-treatment (s.c.) of mice with DH(2)O, L-arginine (20 mg/kg), N(G)-monomethyl-L-arginine acetate (L-NMMA; 20 mg/kg), N(G)-nitro-L-arginine methyl esters (L-NAME; 20 mg/kg), methylene blue (MB) (20 mg/kg), respectively. The AEMC was found to exhibit a concentration-dependent antinociception after pre-challenge with DH(2)O. Interestingly, pre-treatment with L-arginine was found to block significantly (P < 0.05) the AEMC antinociception but only at the highest concentration (100%) of AEMC used. On the other hand, pre-treatment with L-NAME was found to significantly (P < 0.05) enhance the low concentration but inhibit the high concentration AEMC antinociception. MB was found to significantly (P < 0.05) enhance AEMC antinociception at all concentrations used. Except for the higher concentration of AEMC used, co-treatment with L-NAME was found to insignificantly and significantly (P < 0.05) reverse the L-arginine effect when given alone or with low concentration AEMC, respectively. In addition, co-treatment with MB significantly (P < 0.05) reversed the L-arginine effect when given alone or with 10% concentration AEMC but failed to affect the activity of the rest of concentrations used. As a conclusion, this study has demonstrated the involvement of L-arginine/NO/cGMP pathway in AEMC antinociception.
    Matched MeSH terms: Cyclic GMP/metabolism*
  3. Low WY, Ng CJ, Choo WY, Tan HM
    Aging Male, 2006 Sep;9(3):175-80.
    PMID: 17050117 DOI: 10.1080/13685530600914601
    INTRODUCTION: Erectile dysfunction (ED) is a common medical disorder affecting the aging male. A man's perception of a disease affects his health seeking behaviour. This study aimed to explore perceptions of ED among men with ED and how these perceptions came about.
    METHODS: This qualitative study utilized in-depth interviews involving 17 urban men aged between 40 and 75 years old.
    RESULTS: Misconceptions existed regarding the definitions of ED. Most men perceived impotence to be more serious than ED. Although most were aware of the medical causes of ED, 'overuse of penis' and black magic were mentioned as culturally-related causes. ED was perceived as a serious problem associated with loss of manhood and it had a significant impact on relationships with their partners. However, some adopted an 'accepting' view and attributed it to aging and fate. Most men were only familiar with PDE-5 inhibitors and traditional therapies. PDE-5 inhibitors were perceived to be effective but they were concerned about side effects and costs.
    CONCLUSIONS: Identifying men's perceptions of ED and its treatment would help doctors in their consultation, and inform health policy makers in planning appropriate public education and services.
    Matched MeSH terms: 3',5'-Cyclic-GMP Phosphodiesterases/antagonists & inhibitors*
  4. Ajay M, Achike FI, Mustafa MR
    Pharmacol Res, 2007 May;55(5):385-91.
    PMID: 17317209
    In this study, we report the effects of a non-antioxidant flavonoid flavone on vascular reactivity in Wistar-Kyoto (WKY) rat isolated aortae. Whether flavone directly modulates vascular reactivity in spontaneously hypertensive rat (SHR) and streptozotocin-induced diabetic-WKY rat isolated aortae was also determined. Thoracic aortic rings were mounted in organ chambers and exposed to various drug treatments in the presence of flavone (10 microM) or its vehicle (DMSO), which served as control. Pretreatment with flavone enhanced relaxant effects to endothelium-dependent vasodilator acetylcholine (ACh) and attenuated contractile effects to alpha(1)-receptor agonist phenylephrine (PE) in WKY aortae compared to those observed in control aortic rings. Flavone had no effect on relaxations to ACh in WKY aortae incubated with either L-NAME or methylene blue, but enhanced relaxations to ACh in WKY aortae incubated with indomethacin or partially depolarized with KCl. Relaxations to ACh are totally abolished in both control or flavone pretreated endothelium-denuded WKY aortae. Flavone attenuated the inhibition by beta-NADH of ACh-induced relaxation in WKY aortae, but it had no significant effect on the transient contractions induced by beta-NADH nor the pyrogallol-induced abolishment of ACh-induced relaxation in WKY aortae. Flavone enhanced endothelium-independent relaxation to sodium nitroprusside (SNP) in both endothelium-intact and -denuded WKY aortae. Flavone enhanced relaxation to ACh and SNP as well as attenuated contractile effects to PE in SHR and diabetic aortae, a finding similar to that observed in normal WKY aortae. From these results, we conclude that flavone modulates vascular reactivity in normal as well as hypertensive and diabetic aortae. These effects of flavone results probably through enhanced bioactivity of nitric oxide released from the endothelium.
    Matched MeSH terms: Cyclic GMP/metabolism
  5. Sosroseno W, Sugiatno E, Samsudin AR, Ibrahim MF
    Biomed Pharmacother, 2008 Jun;62(5):328-32.
    PMID: 17988826
    The aim of the present study was to determine the effect of nitric oxide (NO) on the production of cyclic AMP (cAMP) by a human osteoblast cell line (HOS cells) stimulated with hydroxyapatite. Cells were cultured on the HA surfaces with or without the presence of NO donors (SNAP and NAP) for 3 days. The effect of adenylyl cyclase inhibitor (SQ22536), NO scavenger (carboxy PTIO) or endothelial nitric oxide synthase (eNOS) inhibitor (L-NIO), was assessed by adding these to the cultures of HA-stimulated HOS cells with or without the presence of SNAP. Furthermore, HOS cells were pre-treated with anti-human integrin alphaV antibody prior to culturing on HA surfaces with or without the presence of SNAP. The levels of cAMP and cGMP were determined from the 3-day culture supernatants. The results showed that the production of cAMP but not cGMP by HA-stimulated HOS cells was augmented by SNAP. SQ22536 and carboxy PTIO suppressed but L-NIO only partially inhibited the production of cAMP by HA-stimulated HOS cells with or without the presence of exogenous NO. Pre-treatment of the cells with anti-human integrin alphaV antibody suppressed the production of cAMP by HA-stimulated HOS cells with or without the presence of NO. Therefore, the results of the present study suggest that NO may up-regulate the production of cAMP, perhaps, by augmenting adenylyl cyclase activity initiated by the binding between HOS cell-derived integrin alphaV and HA surface.
    Matched MeSH terms: Cyclic GMP/biosynthesis
  6. Sosroseno W, Sugiatno E
    Acta Biomed, 2008 Aug;79(2):110-6.
    PMID: 18788505
    BACKGROUND AND AIMS OF THE WORK: Nitric oxide (NO) has been reported to enhance the production of cAMP by hydroxyapatite (HA)-induced a human osteoblast cell line (HOS cells). The aim of the present study was to test the hypothesis that exogenous NO may up-regulate the proliferation of hydroxyapatite (HA)-induced HOS cells via the cyclic-AMP-protein kinase A (PKA) pathway.
    Matched MeSH terms: Cyclic GMP/analogs & derivatives; Cyclic GMP/pharmacology; Cyclic GMP-Dependent Protein Kinases
  7. Sosroseno W, Bird PS, Seymour GJ
    Oral Microbiol. Immunol., 2009 Feb;24(1):50-5.
    PMID: 19121070 DOI: 10.1111/j.1399-302X.2008.00475.x
    Human osteoblasts induced by inflammatory stimuli express an inducible nitric oxide synthase (iNOS). The aim of the present study was to test the hypothesis that Aggregatibacter actinomycetemcomitans lipopolysaccharide stimulates the production of nitric oxide (NO) by a human osteoblast-like cell line (HOS cells).
    Matched MeSH terms: Cyclic GMP/metabolism
  8. Sosroseno W, Bird PS, Seymour GJ
    J Periodontal Res, 2009 Aug;44(4):529-36.
    PMID: 18973550 DOI: 10.1111/j.1600-0765.2008.01157.x
    Elevated nitric oxide (NO) has been associated with destructive periodontal disease. The aim of the present study was to test the hypothesis that exogenous NO may inhibit a protective immune response to Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS) in a murine model.
    Matched MeSH terms: Cyclic GMP/antagonists & inhibitors
  9. Perimal EK, Akhtar MN, Mohamad AS, Khalid MH, Ming OH, Khalid S, et al.
    Basic Clin Pharmacol Toxicol, 2011 Mar;108(3):155-62.
    PMID: 20955360 DOI: 10.1111/j.1742-7843.2010.00635.x
    This study investigated the antinociceptive effects of zerumbone in chemical behavioural models of nociception in mice. Zerumbone given through intraperitoneal route (i.p.) produced dose-related antinociception when assessed on acetic acid-induced abdominal writhing test in mice. In addition, the i.p. administration of zerumbone exhibited significant inhibition of the neurogenic pain induced by intraplantar (i.pl.) injection of capsaicin and bradykinin. Likewise, zerumbone given by i.p. route reduced the nociception produced by i.pl. injection of glutamate and phorbol myristate acetate (PMA). The antinociception caused by zerumbone in the acetic acid test was significantly attenuated by i.p. pre-treatment of mice with l-arginine (nitric oxide precursor) and glibenclamide (ATP-sensitive K(+) channel inhibitor). However, the antinociception of zerumbone was enhanced by methylene blue (non-specific gyanylyl cyclase inhibitor). Together, these results indicate that zerumbone produces pronounced antinociception against chemical models of nociception in mice. It also strongly suggests that the l-arginine-nitric oxide-cGMP-PKC-K(+) ATP channel pathways, the TRPV1 and kinin B2 receptors play an important role in the zerumbone-induced antinociception.
    Matched MeSH terms: Cyclic GMP/antagonists & inhibitors; Cyclic GMP/metabolism*
  10. Mohamad AS, Akhtar MN, Khalivulla SI, Perimal EK, Khalid MH, Ong HM, et al.
    Basic Clin Pharmacol Toxicol, 2011 Jun;108(6):400-5.
    PMID: 21214864 DOI: 10.1111/j.1742-7843.2010.00670.x
    The possible mechanisms of action in the antinociceptive activity induced by systemic administration (intraperitoneal, i.p.) of flavokawin B (FKB) were analysed using chemical models of nociception in mice. It was demonstrated that i.p. administration of FKB to the mice at 0.3, 1.0, 3.0 and 10 mg/kg produced significant dose-related reduction in the number of abdominal constrictions. The antinociception induced by FKB in the acetic acid test was significantly attenuated by i.p. pre-treatment of mice with L-arginine, the substrate for nitric oxide synthase or glibenclamide, the ATP-sensitive K(+) channel inhibitor, but was enhanced by methylene blue, the non-specific guanylyl cyclase inhibitor. FKB also produced dose-dependent inhibition of licking response caused by intraplantar injection of phorbol 12-myristate 13-acetate, a protein kinase C activator (PKC). Together, these data indicate that the NO/cyclic guanosine monophosphate/PKC/ATP-sensitive K(+) channel pathway possibly participated in the antinociceptive action induced by FKB.
    Matched MeSH terms: Cyclic GMP/physiology*
  11. Khalid MH, Akhtar MN, Mohamad AS, Perimal EK, Akira A, Israf DA, et al.
    J Ethnopharmacol, 2011 Sep 01;137(1):345-51.
    PMID: 21664960 DOI: 10.1016/j.jep.2011.05.043
    ETHNOPHARMACOLOGICAL RELEVANCE: Zingiber zerumbet (L.) Smith, a wild edible ginger species or locally known as "lempoyang", commonly used in the Malays traditional medicine as an appetizer or to treat stomachache, toothache, muscle sprain and as a cure for swelling sores and cuts.

    AIM: The present study was conducted to investigate the possible mechanism of actions underlying the systemic antinociception activity of the essential oil of Zingiber zerumbet (EOZZ) in chemical-induced nociception tests in mice.

    MATERIALS AND METHODS: Acetic acid-induced abdominal constriction, capsaicin-, glutamate- and phorbol 12-myristate 13-acetate-induced paw licking tests in mice were employed in the study. In all experiments, EOZZ was administered systemically at the doses of 50, 100, 200 and 300 mg/kg.

    RESULTS: It was shown that EOZZ given to mice via intraperitoneal and oral routes at 50, 100, 200 and 300 mg/kg produced significant dose dependent antinociception when assessed using acetic acid-induced abdominal writing test with calculated mean ID(50) values of 88.84 mg/kg (80.88-97.57 mg/kg) and 118.8 mg/kg (102.5-137.8 mg/kg), respectively. Likewise, intraperitoneal administration of EOZZ at similar doses produced significant dose dependent inhibition of neurogenic pain induced by intraplantar injection of capsaicin (1.6 μg/paw), glutamate (10 μmol/paw) and phorbol 12-myristate 13-acetate (1.6μg/paw) with calculated mean ID(50) of 128.8 mg/kg (118.6-139.9 mg/kg), 124.8 mg/kg (111.4-139.7 mg/kg) and 40.29 (35.39-45.86) mg/kg, respectively. It was also demonstrated that pretreatment with l-arginine (100mg/kg, i.p.), a nitric oxide precursor significantly reversed antinociception produced by EOZZ suggesting the involvement of l-arginine/nitric oxide pathway. In addition, methylene blue (20mg/kg, i.p.) significantly enhanced antinociception produced by EOZZ. Administration of glibenclamide (10mg/kg, i.p.), an ATP-sensitive K(+) channel antagonist significantly reversed antinociceptive activity induced by EOZZ.

    CONCLUSION: Together, the present results suggested that EOZZ-induced antinociceptive activity was possibly related to its ability to inhibit glutamatergic system, TRPV1 receptors as well as through activation of l-arginine/nitric oxide/cGMP/protein kinase C/ATP-sensitive K(+) channel pathway.

    Matched MeSH terms: Cyclic GMP/metabolism
  12. Mohd Fakharul Zaman Raja Yahyai, Athifah Najwani Shahidan
    Scientific Research Journal, 2012;9(1):63-74.
    MyJurnal
    Cyclic guanosine monophosphate (cGMP) is a second messenger molecule involved in the intracellular signalling mechanism which is important in a wide range of cellular process including metabolism, gene expression, cell proliferation and cell death. This study was conducted to determine the effect of fresh (FCC)) and thermoxidized carotino oil (TCO) on erythrocyte cGMP levels from Sprague dawley rats. A total of 30 Sprague dawley rats were randomly segregated into three groups: the first of which was placed on a Fresh Carotino Oil (FCO) diet, the second on a Thermoxidized Carotino Oil (TCO) diet and the control group on commercial rat chow only for a period of 6 and 9 weeks. The two oil diets comprised of 20% (w.10 of each oil mixed with commercial rat,feed. The enzyme immunoassays, performed in week 6, revealed that the erythrocytes cGMP levels for the FCO and TCO groups were 66.198±3.193 pmol/mL and 61.990±6.318 ptnol/mL respectively, and were significantly (p
    Matched MeSH terms: Cyclic GMP
  13. Kamaldin MN, Akhtar MN, Mohamad AS, Lajis N, Perimal EK, Akira A, et al.
    Molecules, 2013 Apr 10;18(4):4209-20.
    PMID: 23612473 DOI: 10.3390/molecules18044209
    Previous studies have shown that systemic administration of 6'-hydroxy-2',4'-dimethoxychalcone (flavokawin B, FKB) exerts significant peripheral and central antinociceptive effects in laboratory animals. However, the mechanisms underlying these peripheral and central antinociceptive effects have yet to be elucidated. Therefore, the objective of the present study was to evaluate the participation of nitric oxide (NO)/cyclic guanosine monophosphate (cGMP)/potassium (K+) channels pathway in the peripheral antinociception induced by FKB. It was demonstrated that intraplantar (i.pl.) administration of FKB (150, 250, 375 and 500 µg/paw) resulted in dose-dependent peripheral antinociception against mechanical hyperalgesia in carrageenan-induced hyperalgesia test model in rats. The possibility of FKB having either a central or a systemic effect was excluded since administration of FKB into the right paw did not elicit antinociception in the contralateral paw. Furthermore, peripheral antinociception induced by FKB (500 µg/paw) was significantly reduced when L-arginine (25 µg/paw, i.pl.), Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 50 µg/paw, i.pl.), glibenclamide (300 µg/paw, i.pl.), tetraethylammonium (300 µg/paw, i.pl.) and charybdotoxin (3 µg/paw, i.pl.) were injected before treatment. Taken together, our present data suggest that FKB elicits peripheral antinociception when assessed in the mechanical hyperalgesia induced by carrageenan. In addition, it was also demonstrated that this effect was mediated through interaction of the NO/cGMP/K+ channels signaling pathway.
    Matched MeSH terms: Cyclic GMP/metabolism*
  14. Zakaria ZA, Sani MH, Mohammat MF, Mansor NS, Shaameri Z, Kek TL, et al.
    Can J Physiol Pharmacol, 2013 Dec;91(12):1143-53.
    PMID: 24289087 DOI: 10.1139/cjpp-2013-0099
    This study was carried out to determine the antinociceptive activity of a novel synthetic oxopyrrolidine-based compound, (2R,3R,4S)-ethyl 4-hydroxy-1,2-dimethyl-5-oxopyrrolidine-3-carboxylate (ASH21374), and to elucidate the involvement of the opioid, vanilloid, glutamate, and nitric oxide - cyclic guanosine monophosphate (NO/cGMP) systems in modulating the observed antinociception. ASH21374, in the doses of 2, 10, and 100 mg/kg body mass, was administered orally to mice 60 mins prior to exposure to various antinociceptive assays. From the results obtained, ASH21374 exhibited significant (P < 0.05) antinociceptive activity in the abdominal constriction, hot-plate, and formalin tests that was comparable with 100 mg/kg acetylsalicylic acid or 5 mg/kg morphine, respectively. ASH21374 also attenuated capsaicin- and glutamate-induced paw licking. Pre-treatment with 5 mg/kg naloxone significantly (P < 0.05) inhibited the activity in all assays, while pretreatment with 10 mg/kg β-funaltraxamine, 1 mg/kg naltrindole, or 1 mg/kg nor-binaltorphimine significantly (P < 0.05) reversed the activity in the abdominal constriction test. l-Arginine, N(G)-nitro-l-arginine methyl esters (l-NAME), methylene blue, and their combinations, failed to inhibit the ASH21374 antinociceptive activity. In conclusion, ASH21374 demonstrated antinociceptive activities on the peripheral and central nervous systems, mediated through the activation of opioid receptors, inhibition of the glutamatergic system, and attenuation of vanilloid-mediated nociceptive transmission. Further studies have been planned to determine the pharmacological potential of ASH21374.
    Matched MeSH terms: Cyclic GMP/metabolism
  15. Bello I, Usman NS, Mahmud R, Asmawi MZ
    J Ethnopharmacol, 2015 Dec 4;175:422-31.
    PMID: 26429073 DOI: 10.1016/j.jep.2015.09.031
    Alstonia scholaris has a long history of use in the Ayurveda traditional treatment of various ailments including hypertension. We have reported the blood pressure lowering activity of the extract of A. scholaris. The following research aim to delineate the pharmacological mechanism involve in the antihypertensive action.
    Matched MeSH terms: Cyclic GMP/metabolism
  16. Yong YK, Chiong HS, Somchit MN, Ahmad Z
    PMID: 26468073 DOI: 10.1186/s12906-015-0901-3
    Histamine is established as a potent inflammatory mediator and it is known to increased endothelial permeability by promoting gap formation between endothelial cells. Previous studies have shown that aqueous extract of Bixa orellana leaves (AEBO) exhibits antihistamine activity in vivo, yet the mechanism of its action on endothelial barrier function remains unclear. Therefore, the current study aimed to determine the protective effect of AEBO against histamine-induced hyperpermeability in vitro.
    Matched MeSH terms: Cyclic GMP/metabolism*
  17. Mokhtar SS, Vanhoutte PM, Leung SW, Suppian R, Yusof MI, Rasool AH
    Eur J Pharmacol, 2016 Feb 15;773:78-84.
    PMID: 26825543 DOI: 10.1016/j.ejphar.2016.01.013
    Diabetes is associated with endothelial dysfunction, which is characterized by impaired endothelium-dependent relaxations. The present study aimed to examine the role of nitric oxide (NO), prostacyclin and endothelium-dependent hyperpolarization (EDH), in the relaxation of ventral tail arteries of rats under diabetic conditions. Relaxations of tail arteries of control and diabetic rats were studied in wire myograph. Western blotting and immunostaining were used to determine the presence of proteins. Acetylcholine-induced relaxations were significantly smaller in arteries of diabetic compared to control rats (Rmax; 70.81 ± 2.48% versus 85.05 ± 3.15%). Incubation with the combination of non-selective cyclooxygenase (COX) inhibitor, indomethacin and potassium channel blockers, TRAM 34 and UCL 1684, demonstrated that NO-mediated relaxation was attenuated significantly in diabetic compared to control rats (Rmax; 48.47 ± 5.84% versus 68.39 ± 6.34%). EDH-type (in the presence of indomethacin and NO synthase inhibitor, LNAME) and prostacyclin-mediated (in the presence of LNAME plus TRAM 34 and UCL 1684) relaxations were not significantly reduced in arteries of diabetic compared to control rats [Rmax: (EDH; 17.81 ± 6.74% versus 34.16 ± 4.59%) (prostacyclin; 15.85 ± 3.27% versus 17.23 ± 3.75%)]. Endothelium-independent relaxations to sodium nitroprusside, salbutamol and prostacyclin were comparable in the two types of preparations. Western blotting and immunostaining indicated that diabetes diminished the expression of endothelial NO synthase (eNOS), while increasing those of COX-1 and COX-2. Thus, since acetylcholine-induced NO-mediated relaxation was impaired in diabetes because of reduced eNOS protein expression, pharmacological intervention improving NO bioavailability could be useful in the management of diabetic endothelial dysfunction.
    Matched MeSH terms: Cyclic GMP/metabolism
  18. Ling WC, Murugan DD, Lau YS, Vanhoutte PM, Mustafa MR
    Sci Rep, 2016 09 12;6:33048.
    PMID: 27616322 DOI: 10.1038/srep33048
    Sodium nitrite (NaNO2) induces relaxation in isolated arteries partly through an endothelium-dependent mechanism involving NO-eNOS-sGC-cGMP pathway. The present study was designed to investigate the effect of chronic NaNO2 administration on arterial systolic blood pressure (SBP) and vascular function in hypertensive rats. NaNO2 (150 mg L-1) was given in drinking water for four weeks to spontaneously (SHR) and Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) treated hypertensive SD rats. Arterial SBP and vascular function in isolated aortae were studied. Total plasma nitrate/nitrite and vascular cyclic guanosine monophosphate (cGMP) levels were measured using commercially available assay kits. Vascular nitric oxide (NO) levels were evaluated by DAF-FM fluorescence while the proteins involved in endothelial nitric oxide synthase (eNOS) activation was determined by Western blotting. NaNO2 treatment reduced SBP, improved the impaired endothelium-dependent relaxation, increased plasma total nitrate/nitrite level and vascular tissue NO and cGMP levels in SHR. Furthermore, increased presence of phosphorylated eNOS and Hsp-90 was observed in NaNO2-treated SHR. The beneficial effect of nitrite treatment was not observed in L-NAME treated hypertensive SD rats. The present study provides evidence that chronic treatment of genetically hypertensive rats with NaNO2 improves endothelium-dependent relaxation in addition to its antihypertensive effect, partly through mechanisms involving activation of eNOS.
    Matched MeSH terms: Cyclic GMP/metabolism
  19. 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: Cyclic GMP/analogs & derivatives; Cyclic GMP/metabolism; Cyclic GMP/pharmacology
  20. Yam MF, Tan CS, Ahmad M, Ruan S
    Am J Chin Med, 2016;44(7):1413-1439.
    PMID: 27785939
    Orthosiphon stamineus Benth. (Lamiaceae) is an important plant in traditional folk medicine that is used to treat hypertension and kidney stones. In humans, this plant has been tested as an addition regiment for antihypertensive treatment. Among the treatments for hypertension, O. stamineus had been to have diuretic and vasorelaxant effects in animal models. There is still very little information regarding the vasorelaxant effect of O. stamineus. Therefore, the present study was designed to investigate the vasorelaxant activity and mechanism of action of the fractions of O. stamineus. The vasorelaxant activity and the underlying mechanisms of the chloroform fraction of the 50% methanolic extract of O. stamineus (CF) was evaluated on thoracic aortic rings isolated from Sprague Dawley rats. CF caused relaxation of the aortic ring pre-contracted with phenylephrine in the presence and absence of endothelium, and pre-contracted with potassium chloride in endothelium-intact aortic ring. In the presence of endothelium, both indomethacin (a nonselective cyclooxygenase inhibitor) and [Formula: see text]-[1,2,4]Oxadiazolo[4,3-[Formula: see text]]quinoxalin-1-one (ODQ, selective soluble guanylate cyclase inhibitor) had a small effect on the vasorelaxation response. On the other hand, in the presence of Nω-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor), methylene blue (cyclic guanosine monophosphate lowering agent), tetraethylammonium ([Formula: see text], nonselective calcium activator [Formula: see text] channel blocker), 4-aminopyridine (4-AP, voltage-dependent [Formula: see text] channel blocker), barium chloride ([Formula: see text], inwardly rectifying [Formula: see text] channel blocker), glibenclamide (nonspecific ATP-sensitive [Formula: see text] channel blocker), atropine (muscarinic receptor blocker) and propranolol (β-adrenergic receptor blocker), the vasorelaxant effect significantly reduced the relaxation stimulated by CF. CF was also found to be active in reducing [Formula: see text] release from the sarcoplasmic reticulum and blocking calcium channels.
    Matched MeSH terms: Cyclic GMP/metabolism*
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