Effect Of 3-morpholinosydnonimine Research Articles

Inhibition of MG132-induced mitochondrial dysfunction and cell death in PC12 cells by 3-morpholinosydnonimine

The effect of 3-morpholinosydnonimine (SIN-1) against the cytotoxicity of MG132, a proteasome inhibitor, in differentiated PC12 cells was assessed by measuring the effect on the mitochondrial membrane permeability. Treatment of PC12 cells with MG132 resulted in the nuclear damage, decrease in the mitochondrial transmembrane potential, cytosolic accumulation of cytochrome c, activation of caspase-3, increase in the formation of reactive oxygen species (ROS), and depletion of GSH. Addition of SIN-1, a producer of nitric oxide (NO) and superoxide, differentially reduced the MG132-induced cell death and GSH depletion concentration dependently with a maximal inhibitory effect at 150 μM. Carboxy-PTIO, superoxide dismutase, Mn-TBAP, and ascorbate prevented the inhibitory effect of SIN-1 on the cytotoxicity of MG132. SIN-1 inhibited the MG132-induced change in the mitochondrial membrane permeability, ROS formation and decrease in GSH contents in PC12 cells. S-nitroso- N-acetyl- dl-penicillamine reduced the MG132-induced cell death in PC12 cells, whereas peroxynitrite and H 2O 2 did not affect the cytotoxicity of MG132. The results suggest that NO and superoxide liberated from SIN-1 exert an inhibitory effect against the cytotoxicity of MG132. SIN-1 may inhibit the MG132-induced viability loss in PC12 cells by suppressing change in the mitochondrial membrane permeability that is associated with oxidative damage.

Mitogen-activated protein kinases mediate peroxynitrite-induced cell death in human bronchial epithelial cells

Peroxynitrite, formed by the reaction of nitric oxide (NO. ) with superoxide anions (O(2)(-).), may play a role in the pathophysiology of inflammation. The effects of 3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, on the human bronchial epithelial cell line BEAS-2B, were examined. SIN-1 exposure resulted in cell death in a time- and dose-dependent manner. Depletion of intracellular glutathione increased the vulnerability of the cells. Pretreatment with Mn(III)tetrakis(N-methyl-4'-pyridyl)porphyrin (MnTMPyP) or hydroxocobalamin (HC), O(2)(-). and NO. scavengers, respectively, reduced significantly SIN-1-induced cell death (18.66 +/- 3.57 vs. 77.01 +/- 14.07 or 82.20 +/- 9.64, % cell viability SIN-1 vs. MnTMPyP or HC). Moreover, the mitogen-activated protein kinases (MAPK) p44/42 (ERK), p38, and p54/46 (JNK) were also activated in a time- and concentration-dependent manner. PD-98059 and SB-239063, specific inhibitors of ERK and p38 MAPK pathways, failed to protect cells against 1 mM SIN-1. However, PD-98059 partially inhibited (60% cell survival) SIN-1 effects at < or =0.25 mM, and this was increased with the inclusion of SB-239063. Therefore, MAPKs may mediate signal transduction pathways induced by peroxynitrite in lung epithelial cells leading to cell death.

Protective Effect of Pine Leaf against Peroxynitrite-mediated Renal Epithelial Cell Injury

The effect of pine leaf extract and its constituent compounds, gallic acid and galloyl gallic acid, on cell injury were determined in the cultured renal epithelial cell line, LLC-PK1. The cytotoxic effect of 3-morpholinosydnonimine (SIN-1), thought to form peroxynitrite (ONOO−) as a simultaneous superoxide (O2−) and nitric oxide (NO) generator, was inhibited by pine leaf extract, and more potently by gallic acid and galloyl gallic acid. The extract inhibited ONOO− formation by SIN-1 and scavenged ONOO− directly. Compared with the extract, gallic acid and galloyl gallic acid had potent ONOO−-scavenging activity, indicating that tannin may contribute to the activity of pine leaf extract. Both sodium nitroprusside as a NO generator and pyrogallol as an O2− generator, enhanced cytotoxicity in epithelial cells, and this effect was not abolished by the extract, gallic acid or galloyl gallic acid. The results suggest that pine leaf may exert a protective effect against ONOO−-mediated epithelial cell injury.

Effect of 5-aminosalicylic acid and 4-aminosalicylic acid on precontracted rat aortic strips and on NO-mediated inhibition of platelet aggregation

We have examined the interactions of 5-aminosalicylic acid (5-ASA) and 4-aminosalicylic acid (4-ASA) with nitric oxide (NO) on rat aorta and human platelets. Phennylephrine-precontracted rat aortic strips with intact endothelium were further contracted by 5-ASA (50–200 μmol/1) and 4-ASA (1–20 mmol/1) in a concentration-dependent manner. Removal of endothelium, inhibition of guanylate cyclase by methylene blue, inhibition of NO biosynthesis byNG-nitro-l-arginine as well as inactivation of NO by oxyhemoglobin abolished the effects of 5-ASA and 4-ASA. The antiaggregatory effects of 3-morpholinosydnonimine (SIN-1) and rat peritoneal neutrophils (RPN) were diminished in a concentration-dependent manner by 5-ASA (50–250 μmol/l), but not by 4-ASA (up to 20 mmol/l). In the presence of superoxide dismutase (SOD), 5-ASA did not antagonize NO-mediated effects on platelets. 5-ASA up to 100 μmol/l did not affect NO synthase from rat brain, while a concentration of 1 mM caused 21% inhibition. Since NO might act as a cytotoxic mediator, our results suggest that inactivation of NO by 5-ASA and higher concentrations of 4-ASA could contribute to the therapeutic activity of the drugs in inflammatory bowel disease (IBD).

Effect of 3-morpholinosydnonimine (SIN-1) and NG-nitro-L-arginine (NNA) on isolated perfused anaphylactic guinea-pig hearts.

The modulating effects of exogenous and endogenous nitric oxide (NO) on the cardiac anaphylactic reaction and eicosanoid release were investigated in isolated perfused sensitized guinea-pig hearts using 3-morpholinosydnonimine (SIN-1), the active metabolite of molsidomine, as NO-donor and NG-nitro-L-arginine (NNA) as an inhibitor of NO biosynthesis. Infusion of SIN-1 (final concentrations in the perfusates 0.3 or 1.0 mmol/l) elevated coronary flow under basal conditions as well as during cardiac anaphylaxis, while NNA (0.1 mmol/l) decreased basal coronary flow and aggravated the anaphylactic coronary constriction. Both drugs did not modify the characteristic biphasic profile of the coronary constriction after antigen challenge with an initial more severe phase followed by a less pronounced long-lasting flow reduction. Neither SIN-1 nor NNA affected spontaneous heart rate. However, while NNA tended to prolong the duration of antigen-induced arrhythmias, SIN-1 (1 mmol/l) had an inhibitory effect. This protection might be related to the increased coronary flow in the presence of SIN-1. SIN-1 inhibited anaphylactic release of cysteinyl-leukotrienes (LT) and 6-keto-prostaglandin (PG) F1 alpha, but did not influence thromboxane (TX) B2 release. On the other hand, NNA (0.1 mmol/l) inhibited anaphylactic release of TXB2, but had only marginal effects on the release of cysteinyl-LT and 6-keto-PGF1 alpha. The results suggest that exogenous and endogenous NO functionally antagonize the effects of vasoconstrictor mediators released after antigen challenge. Additional effects of high concentrations of SIN-1 and NNA on antigen-induced eicosanoid release could modulate the vascular actions of these drugs during cardiac anaphylaxis.

Effect of 3-morpholinosydnonimine (SIN-1), NG-nitro-L-arginine (NNA) and NG-monomethyl-L-arginine (NMMA) on isolated anaphylactic guinea-pig hearts.

In isolated perfused ovalbumin-sensitized guinea-pig hearts modulating effects of nitric oxide (NO) on cardiac function and eicosanoid release were investigated. While the NO-donor SIN-1 exhibited a protective effect during cardiac anaphylaxis, inhibition of NO biosynthesis by NNA or NMMA aggravated anaphylactic changes of cardiac functions. Exogenous and endogenous NO seems to functionally antagonize the effects of vasoconstrictor mediators released during the anaphylactic reaction. In addition, inhibition of cysteinyl-leukotriene (cys-LT) release could contribute to the protective effect of SIN-1 observed.

Effects of SIN-1 on Isolated Canine Basilar Arteries

The effects of 3-morpholinosydnonimine (SIN-1) were studied in isolated canine basilar arteries. Rings with and without endothelium were suspended in Krebs-Ringer bicarbonate solution bubbled with 95% O2-5% CO2. Changes in isometric force were recorded. SIN-1, nitric oxide, and sodium nitroprusside caused concentration-dependent relaxations of control preparation contracted by uridine-5'-triphosphate. The removal of endothelium augmented the relaxation to the nitrovasodilators. Increasing concentrations of SIN-1 reduced endothelium-dependent contractions to the calcium ionophore A23127 and arachidonic acid. The results of the present study suggest that SIN-1 causes relaxation and prevents endothelium-dependent contractions in cerebral arteries. The inhibitory effect of SIN-1 is reduced by the presence of endothelium possibly by interaction with endothelium-derived relaxing factors and/or superoxide anions produced in endothelial cells. The inhibition of endothelium-dependent contractions could be due in part to chemical interactions between endothelium-derived contracting factor (superoxide anion) and the nitric oxide liberated by SIN-1.

Effects of metabolites of Molsidomine on coronary arteries - Coronary vasodilation and activation of guanylate cyclase

The effects of 3-morpholinosydnonimine (SIN-I) and N-nitroso-N-morpholinoaminoacetonitrile (SIN-IA) on coronary arteries were studied in vitro and in vivo, using canine isolated coronary arterial strips and canine extracorporeal carotid-coronary bypass circuit.