Effects Of Nitric Oxide Donors Research Articles

In vitro effects of nitric oxide donors on apoptosis and oxidative/nitrative protein modifications in ADP-activated platelets

Nitric oxide (NO) is an important physiological signaling molecule. However, when produced in excessive amounts, NO can also have toxic effects. The aim of this study is to investigate the effects of exogenous- and endogenous-derived NO on oxidative modifications of proteins and apoptosis in activated platelets. Washed platelets were incubated with L-arginine or nitroso-glutathione (GSNO) in the presence of adenosine diphosphate (ADP). After incubation, caspase-3 activity, phosphatidylserine (PS) externalization and the potential of mitochondrial membrane as markers of apoptosis were measured. In addition, the alterations in protein carbonylation (PCO) and nitrotyrosine (NT) formation as markers of protein oxidation were examined. Platelet activation with ADP (20 µM) significantly increased PCO and NT levels and apoptotic events. After incubation with L-arginine, platelet NO production increased significantly. This L-arginine-induced increase caused decreases in formerly increased PCO and NT levels associated with ADP-induced platelet activation. Stimulation of NO production with L-arginine protected platelets from apoptosis. GSNO caused an increase in protein NT levels. Despite this change, GSNO was effective in inhibition of P-selectin expression, platelet aggregation, protein carbonylation and apoptosis. The results suggest that L-arginine and GSNO-mediated NO leads to the inhibition of key apoptotic processes including caspase-3 activation, PS exposure and low mitochondrial membrane potential in washed platelets. The inhibitory effect of platelet clearance of L-arginine and GSNO may be a novel useful therapeutic property in clinical application.

The effect of acrylamide and nitric oxide donors on human mesenchymal progenitor cells

We have examined the effects of nitric oxide donors and acrylamide on mesenchymal progenitor cell (hMPC) viability, programmed cell death (PCD) and differentiation. Acrylamide was examined at 0.5mM and 1.5mM concentrations, NOC-18 at 10μM and SNP at 100μM. Cell viability was assayed with MTS, PCD was determined by phosphatidylserine, caspase-9 and -3/7 and mitochondrial membrane potential assays, and osteogenic cell differentiation was evaluated by alkaline phosphatase activity (ALP) and mRNA levels for collagen type I, bone sialoprotein, ostepontin and osteocalcin. Serum-free hMPC cultures treated with 1.5mM acrylamide and SNP for 72h demonstrated reduced viability. PCD analyses revealed that SNP stimulated cells to necrosis in reactive species-dependent manner. Acrylamide (1.5mM) led to apoptosis independent of reactive species. Acrylamide and SNP reduced ALP activity and collagen type I mRNA levels but mRNA levels for bone sialoprotein and osteopontin increased in SNP treated cells and remained unchanged in acrylamide. Acrylamide had no effect on guanylate cyclase and cGMP osteogenic signaling pathway. The study suggests that acrylamide might impair bone development and remodeling upon acute or prolonged intoxication with this compound of mesenchymal cells.

Effect of nitric oxide on expression of apoptotic genes and HSP70 in drosophila

Data on involvement of nitric oxide in apoptosis are contradictory. The balance between anti- and proapoptotic activities of nitric oxide depends on many factors, including its concentration in a tissue and interactions with other regulators of apoptosis. This paper describes the results of a series of experiments on the effect of nitric oxide donors and inhibitors as well as dNOS1 and dNOS4 transgenes on the apoptosis on drosophila LobeRSV mutant strain and wild-type strain Oregon R. It has been shown that a high nitric oxide content in cells is able to inhibit antiapoptotic effect of HSP70 and stimulate apoptosis, possibly, via the grim-mediated apoptotic pathway. Moreover, long-term action of a high nitric oxide concentration during the entire development more efficiently stimulates the proapoptotic genes as compared with short-term action of this agent.

Hyperoxia attenuates the inhibitory effect of nitric oxide donors on HIF prolyl-4-hydroxylase-2: Implication on discriminative effect of nitric oxide on HIF prolyl-4-hydroxylase-2 and collagen prolyl-4-hydroxylase

Prolyl 4-hydroxylases (P4Hs), such as collagen prolyl-4-hydroxylases (CPHs) and hypoxia inducible factor prolyl-4-hydroxylases (HPHs), have recently been recognized as promising drug targets for the treatment of fibrotic and ischemic diseases. CPHs and HPHs catalyze identical metabolic reactions, yet lead to quite different physiological consequences, collagen synthesis and the regulation of oxygen homeostasis. Selective modulation of the two enzymes should provide a therapeutic benefit upon pharmacotherapy. In an in vitro VHL capture assay, hydroxylation of the 19mer HIF peptide (corresponding to HIF-1α residues 556–574) by HPH-2 was effectively prevented by nitric oxide (NO) donors, (±)-S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione. The NO donors also caused inhibition of HPHs and accumulation of nonhydroxylated HIF-1α protein in A549 human lung adenocarcinoma cells. Hyperoxia (100% O 2) attenuated both NO donor-induced accumulation of HIF-1α and inhibition of HPH-mediated hydroxylation. In the presence of a proteasome inhibitor, MG132, the hyperoxia-mediated degradation of HIF-1α was deterred and hydroxylated HIF-1α was detected. SNAP, while being an effective inhibitor of proline 4-hydroxylation of HIF-1α by HPH-2, did not diminish proline hydroxylation of collagen by CPHs. Our data suggest that NO inhibits HPH-2 via competing with dioxygen and that the discriminative effect of NO on CPHs and HPH-2 is attributable to the difference in the affinity of the two enzymes toward dioxygen.

Is Nitroglycerin a Novel and Inexpensive Treatment for Osteoporosis?

Is Nitroglycerin a Novel and Inexpensive Treatment for Osteoporosis?

Effect of nitric oxide donor on viability of human leukemic cells upon arginine deprivation

Some types of tumor cells are unable to synthesize arginine from its precursors. They exhibit growth inhibition and decreased viability in vitro and in vivo under enzymatic arginine deprivation. However, prolonged arginine starvation in human may cause vasoconstriction and thrombosis due to the deficit of arginine derivative, nitric oxide (NO), as vasodilator and disaggregant. This problem can be overcome via supplementation with exogenous NO-donors in vivo , which, in turn, may produce either, pro-apoptotic or anti-apoptotic specific effects on cancer cells under arginine restriction. In this study we elucidated the effect of exogenous NO donor, sodium nitroprusside (SNP) on the viability of human Jurkat leukemic cells under arginine deprivation in vitro . We observed that arginine deprivation suppressed cell proliferation and led to a rapid decrease in cell viability concomitant with progression of apoptosis. According to SNP IC50 determination and apoptosis assays, NO-donor at physiological concentration did not promote survival of tumor cells in arginine-free medium. Moreover, SNP cytotoxicity for Jurkat cells was increased upon arginine withdrawal, suggesting that application of NO donor in vivo may potentially enhance the therapeutic effect of arginine deprivation. Keywords: arginine deprivation, nitric oxide, sodium nitroprusside, apoptosis, leukemic cells.

Divergent Effects of Nitric Oxide Donors on the Biliary Efflux Transporters in Isolated Perfused Rat Livers: Nitric Oxide-Independent Inhibition of ABC Transporters by Sodium Nitroprusside

Rhodamine 123 (RH-123) and its glucuronidated metabolite (RH-Glu) are excreted into the bile via the ABC efflux transporters P-glycoprotein (P-gp) and multidrug resistance-related protein type 2 (Mrp2), respectively. In this study, we investigated the short-term (2 h) effects of a low or high concentration of nitric oxide (NO) donors sodium nitroprusside (SNP) and isosorbide dinitrate (ISDN) on the hepatobiliary disposition of RH-123 and its metabolite in an isolated perfused rat liver model. Additionally, the effects of ISDN on the hepatobiliary disposition of 5 (and 6)-carboxy-2', 7'- dichlorofluorescein (CDF), a specific marker of Mrp2, were investigated in the same model. Whereas SNP caused a substantial (85-90%) reduction in the P-gp- and Mrp2-mediated transport of RH-123 and RH-Glu, respectively, ISDN did not affect either of these transporters. However, ISDN reduced the biliary recovery of RH-Glu, most likely because of inhibition of the formation of the metabolite. Further studies showed that the effects of SNP on these transporters are due to a substantial (88%) depletion of hepatic ATP levels by this NO donor. Additionally, studies using CDF revealed an almost identical hepatobiliary disposition of this Mrp2 marker in the presence or absence of ISDN. It is concluded that short-term exposure of rat livers to NO does not affect the functions of the efflux transporters P-gp and Mrp2. The observed inhibitory effects of SNP on the functions of both P-gp and Mrp2 are via an NO-independent mechanism.

DNA strand breaks and hypoxia response inhibition mediate the radiosensitisation effect of nitric oxide donors on prostate cancer under varying oxygen conditions

Prostate cancer cells can exist in a hypoxic microenvironment, causing radioresistance. Nitric oxide (NO) is a radiosensitiser of mammalian cells. NO-NSAIDs are a potential means of delivering NO to prostate cancer cells. This study aimed to determine the effect and mechanism of action of NO-sulindac and radiation, on prostate cancer cells and stroma, under normoxia (21% oxygen) and chronic hypoxia (0.2% oxygen). Using clonogenic assays, at a surviving fraction of 10% the sensitisation enhancement ratios of radiation plus NO-sulindac over radiation alone on PC-3 cells were 1.22 and 1.42 under normoxia and hypoxia, respectively. 3D culture of PC-3 cells revealed significantly reduced sphere diameter in irradiated spheres treated with NO-sulindac. Neither NO-sulindac nor sulindac radiosensitised prostate stromal cells under normoxia or hypoxia. HIF-1α protein levels were reduced by NO-sulindac exposure and radiation at 21 and 0.2% oxygen. Alkaline Comet assay analysis suggested an increased rate of single strand DNA breaks and slower repair of these lesions in PC-3 cells treated with NO-sulindac prior to irradiation. There was a higher level of γ-H2AX production and hence double strand DNA breaks following irradiation of NO-sulindac treated PC-3 cells. At all radiation doses and oxygen levels tested, treatment of 2D and 3D cultures of PC-3 cells with NO-sulindac prior to irradiation radiosensitised PC-3, with minimal effect on stromal cells. Hypoxia response inhibition and increased DNA double strand breaks are potential mechanisms of action. Neoadjuvent and concurrent use of NO-NSAIDs have the potential to improve radiotherapy treatment of prostate cancer under normoxia and hypoxia.

Effects of Nitric Oxide Donor on Hepatic Arterial Buffer Response in Anesthetized Pigs

ABSTRACTThe effects of systemic administration of exogenous nitric oxide (NO) donor on hepatic arterial buffer response (HABR) have not yet been studied in an anesthetized model. In this study, 28 anesthetized pigs received administration of sodium nitroprusside (SNP) or nitroglycerin (NTG) as exogenous NO donors. Pressure-flow (P-Q) relationships in the hepatic artery defined the pressure at zero flow (PQha = 0) and flow-dependent resistance (R). The magnitude of HABR was evaluated by comparing the change in hepatic arterial blood flow (ΔQha) divided by the change in portal venous blood flow (ΔQpv), using the index of change in blood flow (ΔQha/ΔQpv). Mean arterial pressure decreased from baseline (95.6 ± 3.8 mmHg) to SNP condition (68.3 ± 1.9 mmHg) and decreased from baseline (92.7 ± 4.4 mmHg) to NTG condition (66.2 ± 1.7 mmHg). Mean index of change in blood flow (ΔQha/ΔQpv) was also significantly increased from baseline (0.19 ± 0.12) to SNP condition (0.28 ± 0.17; p = .009) and from baseline (0.18 ± 0.17) to NTG (0.28 ± 0.20; p < .05). In conclusion, systemic administration of SNP and NTG increases HABR with reduced hepatic arterial tone under decreased mean arterial pressure, presumably via exogenous NO enhancing another regulatory system and reducing the pressure gradient for sinusoidal washout.

Effect of nitric oxide donors on membrane tritium accumulation of endocannabinoids and related endogenous lipids

The endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) are metabolised by cells by hydrolysis to arachidonic acid followed by esterification into phospholipids. Here, we report that nitric oxide (NO) donors significantly increase the amount of tritium accumulated in the cell membranes of RBL2H3 rat basophilic cells, 3T3-L1 mouse fibroblast cells and b.End5 mouse brain endothelioma cells following incubation of the intact cells with AEA labelled in the arachidonate part of the molecule. Similar results were seen with 2-AG and with arachidonic acid, whilst the NO donors reduced the accumulation of tritium after incubation of RBL2H3 cells with AEA labelled in the ethanolamine part of the molecule. Pretreatment of intact cells with NO donors did not increase the activity of the enzyme mainly responsible for metabolism of AEA, fatty acid amide hydrolase (FAAH). Furthermore, inhibition of FAAH completely blocked the effect produced by NO donors in cells with a large FAAH component, suggesting that for AEA, the effects were downstream of the enzyme. These data raise the possibility that the cellular processing of endocannabinoids following its uptake can be regulated by nitric oxide.

Effect of Nitric Oxide Donor, a Modulator of Tumor Drug Resistance, on Cell Death and p53 Protein Expression

Exogenous NO donor 3,3-bis-(nitroxymethyl)oxetane (NMO) was synthesized at the Institute for Problems of Chemical Physics (Russian Academy of Sciences). This compound was shown to inhibit cell death (apoptosis and necrosis) in cyclophosphamide-sensitive and cyclophosphamide-resistant P388 murine tumor. p53 protein was expressed in both lines of tumor cells. NO donor NMO had little effect on p53 protein expression in cells of both stains. Our results suggest that the proapoptotic effect of NMO is mediated by the p53-independent molecular mechanisms.

Effects of nitric oxide donors on hIK1 cell surface expression

The human intermediate conductance ion channel, hIK1, is a calcium (Ca2+) activated potassium (K+) channel that has a variety of roles in physiological functions. These functions include cancer development, cell volume regulation, cell growth and cell proliferation. Nitric oxide (NO) is a signaling molecule increased by activation of nitric oxide synthase. Treatment of hIK1 transfected HEK cells with NO‐donors, SNAP and PAP‐NONOate, showed increased hIK1 protein expression levels. Additionally, cell surface immunoprecipitation experiments demonstrated increased levels of hIK1 at the cell surface with NO‐donor treatment. Cell surface expression of hIK1 in untreated HEK cells was evaluated using biotin ligase labeled cells which were treated with strepavidin‐Alexa 488 and detected using confocal microscopy. Channels in untreated HEK cells were rapidly endocytosed and, following a one hour incubation, a majority of the channel was located within endocytic vesicles. Treatment with the NO donors increased cell surface expression of hIK1 after one hour and a decrease in the amount of channel located in endocytic vesicles. These results suggest that NO may regulate hIK1 endocytosis and lead to an increase expression of active channel at the cell surface.

Effect of nitric oxide donors on NADPH oxidase signaling pathway in human neutrophils in vitro

The production of reactive oxygen species (ROS) in activated neutrophils is catalyzed by NADPH oxidase, a multiproteins complex. Various protein kinases including protein kinase C (PKC) and mitogen activated protein kinases (MAPKs) are involved in NADPH oxidase phosphorylation and activation. The main step in the NADPH oxidase activation is phosphorylation of its cytosolic protein p47 phox. We found previously that nitric oxide (NO) donors such as metabolite of molsidomine-SIN-1 and diethylamine/NO significantly impaired the ROS production in activated human neutrophils. In this study, we investigated the effects of both NO donors on NADPH oxidase-linked signaling proteins in activated neutrophils. We found that NO donors decreased the phosphorylation of p47 phox on tyrosine and serine/threonine residues and PKC on serine residues in neutrophils. Both NO donors did not affect the phosphorylation of MAPKs. NO donors partially but significantly lost their ability to reduce ROS production in the presence of PKC but not MAPKs inhibitors. We show that whereas NO donors have no effect on MAPKs activity, they do decrease PMA- and/or fMLP-induced phosphorylation of p47 phox and PKC as well as PMA- and fMLP-induced ROS production.

Dual effect of nitric oxide donor on adjuvant arthritis

The effect of medical use of NO donors on the pathogenesis of arthritis is still yet unclear. We investigated the effects of the NO donor, sodium nitroprusside (SNP), on the pathogenesis of adjuvant-induced arthritis in rats. Rats were given SNP intraperitoneally either from day 5 to day 14 (as a prophylactic protocol) or from day 16 to day 25 (as a therapeutic protocol) after inoculation of adjuvant. SNP administration, whether prophylactic or therapeutic, in doses of 0.1 and 1 mg/kg/d significantly aggravated pathogenesis of adjuvant arthritis in rats. SNP-treated rats showed significant ( P < 0.05) increase in arthritis index, hind paw volume, ankle joint diameter and hyperalgesia compared with control adjuvant arthritic rats. However, in adjuvant rats given the smallest dose of SNP (0.01 mg/kg/d), arthritis index, volume of hind paws, ankle joint diameter, body weight loss, and hyperalgesia were significantly lower than that of control adjuvant rats. After 30 d of the induction of adjuvant arthritis, TNF alpha levels exhibited insignificant changes either in control adjuvant rats or in rats given SNP compared with control non adjuvant rats. IL-10 levels in adjuvant control rats and adjuvant rats given 1 mg or 0.1 mg/kg/d from day 15 to day 25 were significantly lower than that of control non adjuvant rats. Histopathology examination of ankle joint showed that large doses of SNP (1 mg or 0.1 mg/kg/d) increased the mononuclear cells infiltration and erosion of cartilage induced by adjuvant while the infiltration of the inflammatory cells in the synovium of adjuvant rats treated with 0.01 mg/kg/d was minimal and the pannus was inhibited with alleviation of erosion of articular cartilage. Prophylactic small dose of SNP improved the histological status more than the therapeutic small dose. The present work reveals that SNP administration, either prophylactic or therapeutic, was deleterious in higher doses. However, the smallest dose used 0.01 mg/kg/d attenuates joint inflammation, hyperalgesia and body weight loss in adjuvant arthritic rats. These results suggest that small dose of NO donor may exert partial protective effects while the safety of the clinical use of NO donors, in higher doses, in patients with rheumatoid arthritis is questioned.

Nitric Oxide‐Releasing Compounds Inhibit the Production of Interleukin‐2, ‐4 and ‐10 in Activated Human Lymphocytes

In the present study, we investigated the effects of nitric oxide donors, GEA 3162 (1,2,3,4-oxatriazolium,5-amino-3(3,4-dichlorophenyl)-chloride), GEA 3175 (1,2,3,4-oxatriazolium,3-(3-chloro-2-methylphenyl)-5-[[(4-methylphenyl) sulfonyl]amino]-, hydroxide inner salt) and S-nitroso-N-acetylpenicillamine (SNAP), on the production of Th1 [interleukin (IL)-2] and Th2 (IL-4 and IL-10) type cytokines in activated human lymphocytes. Lymphocytes were stimulated with concanavalin A or a combination of thapsigargin and phorbol myristate acetate in the absence or in the presence of nitric oxide donors. Concanavalin A induced expression of IL-2 mRNA and production of IL-2, and the combination of thapsigargin and phorbol myristate acetate induced expression of IL-4 and IL-10 mRNAs and production of IL-4 and IL-10. These effects were inhibited by the nitric oxide donors in a dose-dependent manner, GEA 3162 and GEA 3175 being more potent than SNAP on a molar basis. The results show that nitric oxide donors have immunomodulatory properties in both Th1- and Th2-derived responses.

Effect of Nitric Oxide Donor on IL-6 and PDGF-BB: Comparison of Diabetic Versus Normal Tissue Under Hypoxic and Normoxic Conditions

Statement of the Problem: CDC estimates that 20.8 million people in the US have diabetes. Vascular changes in diabetic tissues result in decreases in oxygenation, platelet derived growth factor (PDGF), and nitric oxide (NO). Fibroblasts and collagen production are significantly reduced in cells from diabetic patients1. Decreased NO production and increased matrix metalloproteinase 8 and 9 occur in wounds of diabetic patients2. Diabetic wounds demonstrate increased inflammatory cytokine secretion, including Interleukin-6. This lab has also demonstrated that the addition of an NO donor can reduce the MMP-8 and MMP-9 expression by fibroblastic cells3. Materials and Methods: Human skin fibroblasts from a diabetic subject were compared to fibroblasts from a non-diabetic patient grown under normoxic and hypoxic conditions. IL-6 and PDGF production were measured. Fibroblasts from a 31yo diabetic and 32yo non-diabetic patients were obtained from the Coriell Institute. Fibroblasts were cultured to confluence and treated with 1nM, 10nM, or 100nM of long-acting SNitrosoglutathione(SNOG) or short-acting FK409 (NOR3) NO donor for 1, 3, or 7 days. Cells were cultured under normoxic (20% oxygen) or hypoxic (2% oxygen) conditions. Appropriate untreated controls were included in all experiments. At harvest, conditioned media from the cultures were assayed for production of IL-6 or PDGF-BB. IL-6 was measured using a ChemiKine® Human Interleukin-6 Sandwich ELISA kit (Chemicon International). PDGF-BB was measured using a Quantikine® Human Immunoassay (RD where significant differences were found, a two-tailed t-test was performed. P-values less than 0.05 were considered significant. Results: After 1, 3, and 7 days in culture, normal fibroblasts produced 23% as much IL-6 as diabetic cells under normoxic conditions. Under hypoxic conditions, normal cells produced an even smaller relative amount of IL-6 (14%). The production of IL-6 by diabetic, but not normal, fibroblasts increased with time in culture. Under normoxic conditions, IL-6 production by diabetic fibroblasts increased from 4.34ng/mg protein to 6.94ng/mg protein from day 1 to day 7, under hypoxic conditions, IL-6 increased from 11.23ng/mg protein to 17.98ng/mg protein. NOR3 had no effect on IL-6 production by any cells under either condition. Treatment with SNOG, decreased IL-6 production by both normal and diabetic fibroblasts, with greater effect on diabetic fibroblasts. Under normoxic conditions, IL-6 production by diabetic cells was dosedependently decreased by up to 81% at the 100nM dose. A smaller response was observed with normal fibroblasts. Only the 100nM dose resulted in a significant decrease in IL-6 production at all three time points. Cells cultured under hypoxic conditions had similar results, but the magnitude was greater in diabetic cells. PDGF-BB was produced by both normal and diabetic fibroblasts. Normal fibroblasts under normoxic conditions synthesized twice as much PDGF-BB as diabetic cells. Under hypoxic conditions, normal cells produced five times the amount of PDGF synthesized by diabetic cells. There were no significant changes in PDGF-BB production with NO donor treatment. Conclusions: Production of PDGF-BB, is significantly reduced under hypoxic conditions in both normal and diabetic cells, but the effect is much greater in the diabetic cells. Synthesis of PDGF-BB by diabetic cells is more influenced by hypoxia than normal cells. Treatment with the NO donor compounds had no effect on PDGF-BB production. Production of IL-6, an inflammatory mediator, is increased in diabetic cells under both normoxic and hypoxic conditions. The addition of SNOG, significantly decreased the amount of IL-6 produced by normal and diabetic cells, but the effect was greater in the diabetic cells.

The effects of nitric oxide donors on the sporulation of Eimeria tenella oocysts

Nitric oxide (NO) is involved in many physiological processes including regulation of blood pressure, immune response, and neural communication. The effects of NO donors on the sporogony of Eimeria tenella oocysts and the blocking effects of NO scavenger, hemoglobin (Hb), against NO donors were investigated in this study. The results showed that the sporulation of oocysts could be completely inhibited by acidic sodium nitrite (NaNO 2), S-nitroso-glutathione (GSNO) or S-nitroso- N-acetyl- dl-penicillamine (SNAP) in profound dose-dependent and time-dependent manners, and the inhibiting process was irreversible and not affected by feces of chickens. However, not all NO donors in this study, such as sodium nitroprusside (SNP), demonstrated above-mentioned effect. The NO scavenger Hb could significantly prevent the detrimental effects of NO donors on the sporogony of oocysts in a dose-dependent manner. At present, the inhibiting mechanism of NO donors on the sporulation of oocysts was still unclear.

Effects of nitric oxide donor and nitric oxide synthase inhibitor on the resistance, exchange and capacitance functions of the canine intestinal vasculature

In the present study, we determined the vascular functions using a canine model of isolated intestinal segment perfused with constant flow. The effects of an NO donor, S-nitroso- N-acetylpenicillamine (SNAP) and an NO synthase inhibitor, N ω-nitro- l-arginine methyl ester ( l-NAME) on the vascular factors (resistance, exchange and capacitance) were evaluated. In condition of venous pressure at 0 mmHg, we determined and calculated arterial pressure (Pa) and capillary pressure (Pc). Vascular factors including total, pre- and post-capillary resistance ( R T, Ra and Rv), vascular compliance (VC) and capillary filtration coefficient ( K fc) were obtained. SNAP at doses 10 − 6 to 10 − 4 mol/l produced vasodilatory effects. It dose-dependently reduced the Pa, Pc, R T and Ra, as well as the Ra/Rv ratio. The Rv was slightly decreased. This agent increased the vascular capacity, VC and K fc. NO inhibition with l-NAME (10 − 6 to 10 − 4 mol/l) produced the opposite effects. The vasoconstrictory effects of l-NAME increased Pa, Pc, R T and Ra as well as the Ra/Rv ratio. It slightly raised the Rv. l-NAME reduced the vascular capacity, VC and K fc. The effects of l-NAME were also dose-dependent. This study has provided a detailed data of the vasodilatory and vasoconstrictory effects NO donation and inhibition on vascular factors in the intestinal vasculature.

P4. Effect of nitric oxide donor on radiation induced MAPK signaling in mouse peritoneal macrophages

P4. Effect of nitric oxide donor on radiation induced MAPK signaling in mouse peritoneal macrophages

Expression of MAdCAM-1 and nuclear factor kappa B and the intervention effect of nitric oxide donor in oxazolone-induced colitis

目的：探讨MAdCAM-1在恶唑酮结肠炎中的表达及一氧化氮供体DETA NONOate和GTN对恶唑酮结肠炎的干预作用.方法：32只C57BL/6小鼠随机分为正常对照组（A）、恶唑酮结肠炎组（B）、GTN干预组（C）和DETA NONOate干预组（D）.除正常对照组外，其余3组均建立小鼠恶唑酮结肠炎模型，两个一氧化氮供体干预后处死小鼠.评价DAI、大体评分和组织学评分；免疫组织化学法检测MAdCAM-1及NF-КB；硝酸还原酶法测定血清中NO含量；测定结肠组织MPO活性.结果：B组小鼠DAI评分自灌肠之日起逐渐增高，而D组则变化不明显.B组小鼠大体评分、组织学评分、NF-КB的表达、MAdCAM-1的表达、MPO活性（3.13±0.84，20.31±2.63，30.29±8.68，17.60±6.53，3.83±0.60）均分别高于A组（0.38±0.52，0.88±0.83，7.38±2.29，4.08±1.30，1.75±0.25，P〈0.01）和D组（1.38±0.52，11.13±1.48，12.60±3.54，8.42±2.16，2.76±0.48，P〈0.01），而C组则与B组相近.B组小鼠血清NO浓度高于A组（54.51±22.28 vs 32.17±14.88，P〈0.05），而低于D组和C组（54.51±22.28 vs 88.53±24.77，80.12±19.79，均P〈0.05）.B组MAdCAM-1的表达与组织学评分、MPO活性、NF-КB P65 L4值呈正相关（r=0.786，r=0.833，r=0.833，P〈0.05）.结论：小鼠恶唑酮结肠炎中结肠固有层MAdCAM-1的表达增加，DETA NONOate可能是治疗溃疡性结肠炎的有价值药物.