s-nitro-n-acetylpenicillamine and 2-phenyl-4-4-5-5-tetramethylimidazoline-1-oxyl-3-oxide

The involvement of NO in O(2)(.-) generation, rootlet development and antioxidant defence were investigated in the adventitious root cultures of mountain ginseng. Treatments of NO producers (SNP, sodium nitroprusside; SNAP, S-nitroso-N-acetylpenicillamine; and sodium nitrite with ascorbic acid), and NO scavenger (PTIO, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl3-oxide) revealed that NO is involved in the induction of new rootlets. Severe decline in number of new rootlets compared to the control under PTIO treatment indicates that NO acts downstream of auxin action in the process. NO producers (SNP, SNAP and sodium nitrite with ascorbic acid) activated NADPH oxidase activity, resulting in greater O(2)(.-) generation and higher number of new rootlets in the adventitious root explants. Moreover, treatment of diphenyliodonium chloride, a NADPH oxidase inhibitor, individually or along with SNP, inhibited root growth, NADPH oxidase activity and O(2)(.-) anion generation. NO supply also enhanced the activities of antioxidant enzymes that are likely to be responsible for reducing H(2)O(2)levels and lipid peroxidation as well as modulation of ascorbate and non-protein thiol concentrations in the adventitious roots. Our results suggest that NO-induced generation of O(2) (.-) by activating NADPH oxidase activity is related to adventitious root formation in mountain ginseng.

Topics: Antioxidants; Ascorbic Acid; Cyclic N-Oxides; Hydrogen Peroxide; Imidazoles; Lipid Peroxidation; NADPH Oxidases; Nitric Oxide; Nitric Oxide Donors; Panax; Penicillamine; Plant Roots; Reactive Oxygen Species; S-Nitroso-N-Acetylpenicillamine; Superoxide Dismutase; Superoxides

Nitric oxide (NO) affects neuronal activity of the midbrain periaqueductal gray (PAG). The purpose of this report was to investigate the role of GABA receptors in NO modulation of neuronal activity through inhibitory and excitatory synaptic inputs within the dorsolateral PAG (dl-PAG). First, spontaneous miniature inhibitory postsynaptic currents (mIPSCs) and excitatory postsynaptic currents (mEPSCs) were recorded using whole cell voltage-clamp methods. Increased NO by either S-nitroso-N-acetyl-penicillamine (SNAP, 100 microM) or L-arginine (50 microM) significantly augmented the frequency of mIPSCs of the dl-PAG neurons without altering their amplitudes or decay time constants. The effects were eliminated after bath application of carboxy-PTIO (NO scavenger), and 1-(2-trifluorom-ethylphenyl) imidazole (NO synthase inhibitor). In contrast, SNAP and L-arginine did not alter mEPSCs in dl-PAG neurons. However the frequency of mEPSCs was significantly increased with prior application of the GABA(B) receptors antagonist, CGP55845. In addition, NO significantly decreased the discharge rate of spontaneous action potentials in the dl-PAG neurons and the effect was reduced in the presence of the GABA(A) receptor antagonist, bicuculline. Our data show that within the dl-PAG NO potentiates the synaptic release of GABA, while NO-induced GABA presynaptically inhibits glutamate release through GABA(B) receptors. Overall, NO suppresses neuronal activity of the dl-PAG via a potentiation of GABAergic synaptic inputs and via GABA(A) receptors.

Topics: 6-Cyano-7-nitroquinoxaline-2,3-dione; Action Potentials; Animals; Cyclic N-Oxides; Drug Interactions; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Female; Free Radical Scavengers; GABA Agents; Imidazoles; In Vitro Techniques; Inhibitory Postsynaptic Potentials; Male; Neural Inhibition; Neurons; Nitric Oxide; Nitric Oxide Donors; Patch-Clamp Techniques; Penicillamine; Periaqueductal Gray; Rats; Rats, Sprague-Dawley; Receptors, GABA

Nitric oxide (NO) is an important signaling molecule in the CNS, regulating neuronal survival, proliferation and differentiation. Here, we explored the mechanism by which NO, produced from the NO donor S-nitroso-acetyl-d-l-penicillamine (SNAP), exerts its neuroprotective effect in purified cultures of chick retinal neurons. Cultures prepared from 8-day-old chick embryo retinas and incubated for 24 h (1 day in culture, C1) were treated or not with SNAP, incubated for a further 72 h (up to 4 days in culture, C4), fixed, and the number of cells estimated, or processed for cell death estimation, by measuring the reduction of the metabolic dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Experimental cultures were run in parallel but were re-fed with fresh medium in the absence or presence of SNAP at culture day 3 (C3), incubated for a further 24 h up to C4, then fixed or processed for the MTT assay. Previous studies showed that the re-feeding procedure promotes extensive cell death. SNAP prevented this death in a concentration- and time-dependent manner through the activation of soluble guanylate cyclase; this protection was significantly reversed by the enzyme inhibitors 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) or LY83583, and mimicked by 8-bromo cyclic guanosine 5'-phosphate (8Br-cGMP) (GMP) or 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), guanylate cyclase activators. The effect was blocked by the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). The effect of NO was also suppressed by LY294002, Wortmannin, PD98059, KN93 or H89, indicating the involvement, respectively, of phosphatidylinositol-3 kinase, extracellular-regulated kinases, calmodulin-dependent kinases and protein kinase A signaling pathways. NO also induced a significant increase of neurite outgrowth, indicative of neuronal differentiation, and blocked cell death induced by hydrogen peroxide. Cyclosporin A, an inhibitor of the mitochondrial permeability transition pore considered an important mediator of apoptosis and necrosis, as well as boc-aspartyl (OMe) fluoromethylketone (BAF), a caspase inhibitor, also blocked cell death induced by re-feeding the cultures. These findings demonstrate that NO inhibits apoptosis of retinal neurons in a cGMP/protein kinase G (PKG)-dependent way, and strengthens the notion that NO plays an important role during CNS development.

Topics: Adenosine; Aminoquinolines; Analysis of Variance; Animals; Cell Survival; Cells, Cultured; Chick Embryo; Cyclic GMP; Cyclic N-Oxides; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Inhibitors; Free Radical Scavengers; Imidazoles; Neurons; Nitrates; Nitric Oxide; Nitric Oxide Donors; Nitrites; Penicillamine; Retina; Signal Transduction; Tetrazolium Salts; Thiazoles; Tritium

The activation of NMDA receptors (NMDARs) triggers long-term changes in AMPA receptor-mediated synaptic transmission in the CNS. These long-lasting changes occur via the addition or removal of AMPA receptors (AMPARs) at the synaptic membrane and are mediated by a number of regulatory proteins including the GluR2 AMPAR-interacting proteins n-ethylmaleimide sensitive factor (NSF) and Protein Interacting with C Kinase (PICK1). We have shown that the potent activation of NMDARs drives unclustering of PICK1 and PICK1-GluR2 dissociation in dendrites resulting in increased surface delivery of AMPARs. Here we show that the dispersal of PICK1 is mediated by the actions of NSF. We find that elevated NMDAR signaling leads to the S-nitrosylation of NSF and increased NSF-GluR2 association. Both NMDAR-dependent unclustering of PICK1 and the delivery of surface AMPARs are dependent on release of nitric oxide (NO). Our data suggest that NMDAR activation can drive the surface delivery of AMPARs from a pool of intracellular AMPARs retained by PICK1 through the NO-dependent modification of NSF.

Topics: Animals; Animals, Newborn; Carrier Proteins; Cells, Cultured; Cyclic N-Oxides; Cytoskeletal Proteins; Drug Interactions; Exocytosis; Free Radical Scavengers; Hippocampus; Imidazoles; N-Ethylmaleimide-Sensitive Proteins; Neurons; Nitric Oxide; Nitric Oxide Donors; Nuclear Proteins; Patch-Clamp Techniques; Penicillamine; Rats; Receptors, AMPA; RNA, Small Interfering

In locusts, a central pattern generator underlies the rhythmic movements of the ovipositor valves that serve to drive the abdomen into damp soil in order to lay eggs. We have investigated the role of nitric oxide (NO) in the control of this oviposition digging rhythm. NO increases the frequency of the rhythm by acting via sGC to elevate cGMP, which in turn acts via PKG. Increasing exogenous NO levels using the NO donors SNAP and PAPANONOate increased the cycle frequency of the fictive digging rhythm, as did increasing endogenous NO by bath application of the substrate for NOS, l-arginine. On the other hand, application of the NO scavenger PTIO decreased the cycle frequency, indicating that NO must normally exert a continuous and dynamic role on the central pattern generator underlying the oviposition rhythm. Inhibiting the main molecular target of NO, soluble guanylate cyclase, with ODQ reduced the cycle frequency of the rhythm, suggesting that NO mediated its effects via sGC and cyclic GMP. Further evidence for this was produced by bath application of 8-Br-cGMP, which increased the frequency of the rhythm. Bath application of the generic protein kinase inhibitor and a selective PKG inhibitor, H-7 and KT-5823, respectively, reduced the frequency of the rhythm, suggesting that PKG acted as a target for cGMP. Thus, we conclude that NO plays a key role in regulating the frequency of the central pattern generator controlling rhythmic egg-laying movements in locusts by acting via sGC/cGMP-PKG.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Animals; Behavior, Animal; Carbazoles; Cyclic GMP; Cyclic N-Oxides; Female; Grasshoppers; Guanylate Cyclase; Imidazoles; Indoles; Muscles; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Oviposition; Penicillamine; Protein Kinases; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Soluble Guanylyl Cyclase

Nitric oxide (NO) is generated by multiple cell types in the vertebrate retina, including amacrine cells. We investigate the role of NO in the modulation of synaptic function using a culture system containing identified retinal amacrine cells. We find that moderate concentrations of NO alter GABA(A) receptor function to produce an enhancement of the GABA-gated current. Higher concentrations of NO also enhance GABA-gated currents, but this enhancement is primarily due to a substantial positive shift in the reversal potential of the current. Several pieces of evidence, including a similar effect on glycine-gated currents, indicate that the positive shift is due to an increase in cytosolic Cl-. This change in the chloride distribution is especially significant because it can invert the sign of GABA- and glycine-gated voltage responses. Furthermore, current- and voltage-clamp recordings from synaptic pairs of GABAergic amacrine cells demonstrate that NO transiently converts signaling at GABAergic synapses from inhibition to excitation. Persistence of the NO-induced shift in E(Cl-) in the absence of extracellular Cl- indicates that the increase in cytosolic Cl- is due to release of Cl- from an internal store. An NO-dependent release of Cl- from an internal store is also demonstrated for rat hippocampal neurons indicating that this mechanism is not restricted to the avian retina. Thus signaling in the CNS can be fundamentally altered by an NO-dependent mobilization of an internal Cl- store.

Topics: Amacrine Cells; Animals; Animals, Newborn; Bumetanide; Cells, Cultured; Chick Embryo; Cyclic N-Oxides; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Electric Stimulation; Free Radical Scavengers; Furosemide; gamma-Aminobutyric Acid; Glycine; Hippocampus; Imidazoles; Membrane Potentials; Mesylates; Models, Neurological; Neural Inhibition; Nitric Oxide; Nitric Oxide Donors; Patch-Clamp Techniques; Penicillamine; Potassium; Rats; Rats, Inbred F344; Retina; Sodium; Sodium Potassium Chloride Symporter Inhibitors; Synapses

Sodium nitroprusside (SNP) is a nitric oxide (NO) donor drug, which is therapeutically used as a vasodilating drug in heart transplantations. In our previous study it was found that SNP at a concentration of 100 microM inhibited mineralization in a cell culture system, indicating that the beneficial effects of this drug may also include inhibition of vascular calcification. The aim of this study was to investigate which bioactive compounds generated from SNP inhibit mineralization. ATDC5 cells were grown for 14 days and mineralization was induced by addition of 5 mM phosphate for 24 h. Mineralization was determined by staining precipitated calcium with an alizarin red stain. It was found that the NO donors S-nitrosoglutathione and S-nitroso-N-acetylpenicillamine were not able to inhibit mineralization and NO scavengers could not antagonize the inhibiting effect of SNP on mineralization. The iron chelator deferoxamine (200 microM) antagonized the inhibiting effect on mineralization mediated by SNP and ammonium iron sulfate inhibited mineralization in a dose-dependent manner (10-100 microM). Furthermore, iron ions (30 microM) were detected to be released from SNP in the cell culture. These data show that the iron moiety of sodium nitroprusside, rather than nitric oxide inhibits mineralization.

Topics: Animals; Bepridil; Calcium; Catalase; Cell Line; Cyclic N-Oxides; Dose-Response Relationship, Drug; Ferric Compounds; Ferricyanides; Ferrous Compounds; Free Radical Scavengers; Imidazoles; Iron; Mannitol; Minerals; Molecular Structure; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Oxidation-Reduction; Penicillamine; Quaternary Ammonium Compounds; Reactive Oxygen Species; S-Nitrosoglutathione; Superoxide Dismutase

In crayfish, movement of the tailfan causes stimulation of exteroceptive sensory hairs located on its surface. Movement is monitored by a proprioceptor, the protopodite-endopodite chordotonal organ within the tailfan. Proprioceptive afferents provide indirect presynaptic inhibitory inputs to sensory hair afferents in the form of primary afferent depolarizations (PADs). Bath application of nitric oxide (NO) substrates, donors and scavengers, and nitric oxide synthase (NOS) inhibitors had no effect on the responses of proprioceptive afferents during imposed movements of the chordotonal organ. In contrast, the amplitude of PADs in exteroceptive hair afferents was dependent on NO levels. NO levels were altered by bath-application of the NO-precursor L-arginine, the NO donor SNAP, the NOS-inhibitor L-NAME, and the NO scavenger PTIO, while changes in PAD amplitude were measured. Application of L-arginine or SNAP resulted in consistent decreases in PAD amplitude, whereas L-NAME and PTIO induced increases in PAD amplitude. These results suggest that endogenous NO decreases inhibitory inputs to exteroceptive neurons, thus enhancing transmitter release at their output synapses.

Topics: Animals; Antidotes; Arginine; Astacoidea; Cyclic N-Oxides; Electrophysiology; Enzyme Inhibitors; Female; Free Radical Scavengers; Ganglia, Invertebrate; Imidazoles; Male; Mechanoreceptors; Neural Inhibition; Neurons, Afferent; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Penicillamine; Physical Stimulation; Presynaptic Terminals; Proprioception

Electrical stimulation of sensory neurons that innervate receptors on the tailfan of crayfish evokes a reflex response of motor neurons that produce movements of the blades of the tailfan, the uropods. We analyzed the modulatory effects of nitric oxide (NO) on the spike frequency of the reflex response. Bath application of L-arginine and SNAP, which elevate endogenous and exogenous NO levels, increased the frequency of the evoked response, whereas the application of L-NAME and PTIO, which reduce NO levels, decreased the frequency of the response. To determine through what pathway and target NO exerted these effects we bath applied ODQ, an inhibitor of soluble guanylyl cyclase (sGC), which decreased the frequency of response, and 8-br-cGMP, which increased the spike frequency of response. To provide further evidence that NO acts via sGC, we elevated NO levels with L-arginine while simultaneously inhibiting sGC with ODQ. This application reduced the response to control levels, indicating that NO in the terminal ganglion of crayfish acts via sGC to modulate cGMP levels, which in turn regulate the responses of the uropod motor neurons.

Topics: Analysis of Variance; Animals; Arginine; Astacoidea; Cyclic GMP; Cyclic N-Oxides; Drug Interactions; Electric Stimulation; Enzyme Inhibitors; Excitatory Postsynaptic Potentials; Female; Free Radical Scavengers; Imidazoles; In Vitro Techniques; Male; Muscles; Neurons; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Oxadiazoles; Penicillamine; Picolines; Quinoxalines; Reflex; Thionucleotides

Increased release of oxidants has been implicated in the pathogenesis of pulmonary fibrosis. Previous work in the rat showed that formation of the early fibrotic lesion is associated with increased expression of inducible nitric oxide synthase (iNOS) in pulmonary fibroblasts. The aim of this study was to test the hypothesis that NO is involved in the activation of pulmonary fibroblasts. The effects of endogenous and exogenous NO on proliferation of human pulmonary fibroblasts were investigated by administration of cytomix or SNAP, respectively. At low concentrations, both treatments increased cell numbers, an effect attenuated by iNOS inhibitor or NO scavenger. Induction of iNOS was confirmed by measurement of nitrate/nitrite production and by immunodetection. Quantitative RT-PCR showed an increase in iNOS mRNA as early as 3 h after stimulation. These results support the hypothesis and show that upregulation of the iNOS gene is an early event in the proliferative response of human lung fibroblasts to inflammatory stimuli.

Topics: Blotting, Western; Cell Division; Cell Line; Cyclic N-Oxides; Cytokines; Enzyme Inhibitors; Fibroblasts; Free Radical Scavengers; Gene Expression Regulation; Humans; Imidazoles; Interferon-gamma; Interleukin-1; Lung; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; omega-N-Methylarginine; Penicillamine; Pulmonary Fibrosis; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stimulation, Chemical; Tumor Necrosis Factor-alpha

Recent studies have revealed that administration of nitric oxide (NO) donors increases the release of neurotransmitters in various brain regions. In the retina, NO synthetase (NOS) is found in retinal amacrine and ganglion cells, and it is evident that NO is involved in encoding visual information. In the present study, therefore, NO donors were used to study the effect of exogenous NO on the high K(+)-evoked release of endogenous acetylcholine (ACh) in the rat retina.. Isolated rat retinal preparations were superfused with modified Krebs-Ringer bicarbonate buffer solution. In each experiment, stimulation for 10 min with 30 mM KCl was done twice. The amounts of ACh released by the first or second KCl stimulation were termed S1 and S2 respectively. Test agents were applied just before the second KCl stimulation. The effects of test agents were evaluated as S2 divided by S1. ACh was converted to hydrogen peroxide and electrochemically assayed by high-performance liquid chromatography.. S-Nitro-N-acetyl-DL-penicillamine (SNAP), an NO donor, dose-dependently inhibited the high K(+)-evoked release of endogenous ACh. Such inhibition by NO was confirmed also by another NO donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxy imino]-5-nitro-3-hexenamide (NOR3). The inhibitory effect of SNAP was abolished by both carboxy-PTIO, an NO scavenger, and bicuculline, an antagonist of GABAA receptors.. The NO-induced decrease of ACh release is probably due to an NO-induced increase of GABAergic system inhibition.

Topics: Acetylcholine; Animals; Bicuculline; Cyclic N-Oxides; Dose-Response Relationship, Drug; Free Radical Scavengers; GABA Antagonists; Imidazoles; Male; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitro Compounds; Penicillamine; Potassium Chloride; Rats; Rats, Wistar; Retina

The role of nitric oxide (NO) in the survival of retinal ganglion cells (RGCs) was investigated.. RGCs were purely isolated from postnatal Sprague-Dawley rats by 2-step panning and were cultured in chemically defined serum free medium. An NO releaser, S-nitroso-N-acetylpenicillamine (SNAP: 500 microM, 250 microM, 100 microM, 10 microM, 1 microM, 100 nM, and 10 nM), an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5 tetramethylimidazoline-1-oxyl-3-oxide potassium salt (c-PTIO: 100 microM, 33 microM, 10 microM, 1 microM), mixture of 100 microM SNAP and 33 microM c-PTIO, N(G)-nitro-L-arginine methyl ester (L-NAME: 10 mM, 5 mM, 500 microM, 100 microM or 10 microM), or their vehicles were added to the medium of pure RGC culture for 48 hr. Survival rates of small and large RGCs were determined separately by flow cytometry.. At > or = 100 microM, SNAP significantly reduced RGC survival in a concentration dependent manner. At < or = 41 microM, SNAP significantly increased survival, particularly of large RGCs. c-PTIO and L-NAME reduced the survival rates concentration-dependently. A mixture of 100 microM SNAP and 33 microM c-PTIO significantly improved RGC survival compared with when they were added on their own.. These results indicate that NO exhibits neuroprotective and neurotoxic actions on RGCs and that low concentrations of NO may be beneficial for the survival of neonatal RGCs in vitro.

Topics: Animals; Animals, Newborn; Cell Separation; Cell Survival; Cells, Cultured; Cyclic N-Oxides; Drug Combinations; Enzyme Inhibitors; Flow Cytometry; Free Radical Scavengers; Imidazoles; Immunoenzyme Techniques; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Penicillamine; Rats; Rats, Sprague-Dawley; Retinal Ganglion Cells

Astrocytes provide protection and trophic support to neurons, but like neurons are vulnerable to oxidative stress. Decreased function of astrocytes resulting from oxidative stress could contribute to neurodegeneration. Our goal is to understand the intracellular events associated with oxidative stress in astrocytes. Because nitric oxide (NO) has been implicated as a contributor to oxidative stress in the brain, we examined in this study whether NO contributed to oxidative stress in astrocytes. Stimulation of NO decreases superoxide levels, preserves mitochondrial membrane potential, and decreases mitochondrial swelling in astrocytes treated with peroxide. Chelation of NO is associated with increased cell death, mitochondrial swelling, and loss of mitochondrial membrane potential, in response to peroxide treatment. Peroxide treatment increased intracellular calcium and the peroxide-induced changes in intracellular calcium were not altered in response to NO. Iron-loading increases peroxide-induced oxidative stress in astrocytes, but induction of NO limited the iron effect, suggesting an interaction between iron and NO. These data suggest endogenously produced NO protects astrocytes from oxidative stress, perhaps by preserving mitochondrial function.

Topics: Animals; Antineoplastic Agents; Astrocytes; Cells, Cultured; Cyclic N-Oxides; Free Radical Scavengers; Imidazoles; Interferon-gamma; L-Lactate Dehydrogenase; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Mitochondria; Nitric Oxide; Nitric Oxide Donors; Oxidative Stress; Penicillamine; tert-Butylhydroperoxide

1 The role of protein kinase C (PKC) in colonic cellular injury in response to high concentrations of nitric oxide (NO) released from the donor, S-nitroso-N-acetyl-DL-penicillamine (SNAP) was investigated. 2 Addition of SNAP (0.1-1000 microM) to the cellular suspension resulted in a dose-dependent increase in the extent of damage to isolated colonic mucosal cells as assessed by Trypan blue dye uptake and release of the lysosmal enzyme, N-acetyl-beta-glucosaminidase. SNAP treatment also resulted in an increase in cellular total PKC activity. These increases were reduced or eliminated by pretreatment of the cells with the PKC antagonists staurosporine or GF 109203X or the NO scavenger, phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). 3 PKC-alpha, PKC-delta, PKC-epsilon and PKC-zeta were detected in colonic cellular lysates by immunoblotting. However, only PKC-epsilon protein was increased in response to SNAP treatment. Furthermore, SNAP treatment resulted in activation of PKC-epsilon by causing translocation of the enzyme from the cytosolic to membrane fraction of the cell. This effect was eliminated if cells were preincubated with the NO scavenger, PTIO. 4 The extent of cellular damage in response to addition of SNAP to the incubation medium was enhanced by coincubation with the PKC activator, phorbol 12-myristate 13-acetate (PMA; 1 and 10 microM). 5 PKC activity and the extent of cell damage in response to SNAP were reduced by preincubation of the cells with the peroxyl scavenger, ebselen (0.01-10 microM). 6 These data suggest that the PKC-epsilon isoform of the enzyme mediates NO-induced damage to colonic mucosal cells. This response may occur, at least in part, due to peroxynitrite formation.

Topics: Animals; Azoles; Cell Survival; Colon; Cyclic N-Oxides; Dose-Response Relationship, Drug; Enzyme Activation; Imidazoles; Indoles; Intestinal Mucosa; Isoenzymes; Isoindoles; Male; Maleimides; Nitric Oxide; Nitric Oxide Donors; Organoselenium Compounds; Penicillamine; Protein Kinase C; Rats; Rats, Sprague-Dawley; Staurosporine; Tetradecanoylphorbol Acetate