Effects Of Sodium Nitroprusside Research Articles

PP.12.10

Objective: Increasing evidence suggests nitric oxide (NO) deficit and baroreflex dysfunction to be characteristic for a wide variety of cardiovascular conditions even in preclinical stages of the disease. Sodium nitroprusside (SNP), a spontaneous NO-donor, vasodilatory effect was studied in conjunction with sinocarotid baroreceptor magnetic stimulation and potential implementation in NO deficiency states. Design and method: Mean femoral artery blood pressure (MAP), heart rate (HR) and ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded in conscious rabbits before and after 40-min sinocarotid baroreceptors exposure to 350 mT static magnetic field (SMF), generated by Nd-Fe-B alloy (n = 8) or sham magnets (n = 8, controls). Arterial baroreflex sensitivity (BRS) was measured by changes in HR and MAP after intravenous bolus injections of SNP and phenylephrine. Results: The vasodilatory effect of SNP significantly increased after SMF exposure (MPPGbeforeSMF: 2.57 ± 0.81 V vs. MPPGafterSMF: 7.82 ± 1.61 V, p < 0.0001) and positively correlated with significant increase in BRS (r = 0.51, p = 0.01). Conclusions: Presented findings support the concept that the entire arterial system is under baroreflex control and that it is NO-dependent. The amplification of vascular smooth muscle cells sensitivity to NO suggested to be a new mechanism in baroreflex physiology, which can promote interactions between sympathetic nervous system and NO function, regenerating reduced NO bioavailability, a crucial mechanism of microvascular and endothelial dysfunction. These may generate important etiopathogenetic significance and potential therapeutic implementation in a spectrum of cardiovascular conditions, such as arterial hypertension, coronary heart disease, insulin resistance and diabetes, where sympathovagal imbalance exacerbated by derangements of NO signaling increases cardiovascular risk substantially.

Role of Exogenous Nitric Oxide in Alleviating Iron Deficiency Stress of Peanut Seedlings (Arachis hypogaea L.)

A greenhouse hydroponic experiment was performed to evaluate how peanut seedlings (Arachis hypogaea L.) responded to iron (Fe) deficiency stress in the presence of sodium nitroprusside (SNP), a nitric oxide (NO) donor. The results showed that Fe deficiency inhibited peanut plant growth, decreased chlorophyll and active Fe concentrations, and dramatically disturbed ion balance. The addition of 50, 100, 250, and 500 µM SNP, significantly promoted the absorption of Fe in the cell wall, cell organelles, and soluble fractions, increased the concentrations of active Fe and chlorophyll in peanut plants, and alleviated the excess absorption of manganese (Mn) and copper (Cu) induced by Fe deficiency. In addition, SNP also significantly increased the activities of superoxide dismutase, peroxidase, and catalase, which is beneficial to inhibit the accumulation of malondialdehyde and reactive oxygen species. Addition of 250 µM SNP had the most significant alleviating effect against Fe-deficiency stress, and after 15 days of treatment, the plants with the 250 µM SNP treatment achieved comparable NO levels with those grown under optimal nutrition conditions. However, the effects of SNP were reversed by addition of hemoglobin (Hb, a NO scavenger). These results suggest that NO released from SNP decomposition was responsible for the effect of SNP-induced alleviation on Fe deficiency.

Reactive Oxygen Species and Nitrogen Species Differentially Regulate Neuronal Excitability in Rat Spinal Substantia Gelatinosa Neurons

Reactive oxygen species (ROS) and nitrogen species (RNS) are implicated in cellular signaling processes and as a cause of oxidative stress. Recent studies indicate that ROS and RNS are important signaling molecules involved in nociceptive transmission. Xanthine oxidase (XO) system is a well-known system for superoxide anions (O2˙-) generation, and sodium nitroprusside (SNP) is a representative nitric oxide (NO) donor. Patch clamp recording in spinal slices was used to investigate the role of O2˙- and NO on substantia gelatinosa (SG) neuronal excitability. Application of xanthine and xanthine oxidase (X/XO) compound induced membrane depolarization. Low concentration SNP (10μM) induced depolarization of the membrane, whereas high concentration SNP (1 mM) evoked membrane hyperpolarization. These responses were significantly decreased by pretreatment with phenyl N-tert-butylnitrone (PBN; nonspecific ROS and RNS scavenger). Addition of thapsigargin to an external calcium free solution for blocking synaptic transmission, led to significantly decreased X/XO-induced responses. Additionally, X/XO and SNP-induced responses were unchanged in the presence of intracellular applied PBN, indicative of the involvement of presynaptic action. Inclusion of GDP-β-S or suramin (G protein inhibitors) in the patch pipette decreased SNP-induced responses, whereas it failed to decrease X/XO-induced responses. Pretreatment with n-ethylmaleimide (NEM; thiol-alkylating agent) decreased the effects of SNP, suggesting that these responses were mediated by direct oxidation of channel protein, whereas X/XO-induced responses were unchanged. These data suggested that ROS and RNS play distinct roles in the regulation of the membrane excitability of SG neurons related to the pain transmission.

Baroreceptor stimulation enhanced nitric oxide vasodilator responsiveness, a new aspect of baroreflex physiology

ObjectiveIncreasing evidence suggests that endothelial nitric oxide (NO) deficit and baroreflex dysfunction are associated with a variety of cardiovascular conditions, ranging from arterial hypertension to stroke and coronary heart disease, importantly appearing even in preclinical stages of the disease. To test the hypothesis that the arterial baroreflex has a modulatory effect on NO-dependent vasodilation, sodium nitroprusside (SNP), a spontaneous NO-donor, vasodilatory effect was studied in conjunction with sinocarotid baroreceptor magnetic stimulation and potential implementation in NO deficiency states. MethodsMean femoral artery blood pressure (MAP), heart rate (HR) and ear lobe skin microcirculatory blood flow, measured by a microphotoelectric plethysmogram (MPPG), were simultaneously recorded in conscious rabbits before and after 40-min sinocarotid baroreceptor exposure to 350mT static magnetic field (SMF), generated by Nd2–Fe4–B alloy (n=8) or sham magnets (n=8, controls). Arterial baroreflex sensitivity (BRS) was measured by changes in HR and MAP (ΔHR/ΔMAP) after intravenous bolus injections of SNP and phenylephrine. ResultsThe vasodilatory effect of SNP significantly increased after SMF sinocarotid baroreceptor exposure (MPPGbeforeSMF: 2.57±0.81V vs. MPPGafterSMF: 7.82±1.61V, p<0.0001) and positively correlated with significant increase in BRS (r=0.51, p=0.01). ConclusionsBaroreflex-mediated increment in vessel sensitivity to NO is suggested to be a new mechanism in baroreflex physiology with potential implementation in cardiovascular conditions where NO deficit and autonomic dysfunction increase the risk of morbidity and mortality substantially.

Effect of exogenous nitric oxide on antioxidative system and S-nitrosylation in leaves of Boehmeria nivea (L.) Gaud under cadmium stress.

Cadmium (Cd)-induced growth inhibition is one of the primary factors limiting phytoremediation effect of Boehmeria nivea (L.) Gaud in contaminated soil. Sodium nitroprusside (SNP), a donor of nitric oxide (NO), has been evidenced to alleviate Cd toxicity in many plants. However, as an important mechanism of NO in orchestrating cellular functions, S-nitrosylation is still poorly understood in its relation with Cd tolerance of plants. In this study, higher exogenous NO levels were found to coincide with higher S-nitrosylation level expressed as content of S-nitrosothiols (SNO). The addition of low concentration (100 μM) SNP increased the SNO content, and it simultaneously induced an alleviating effect against Cd toxicity by enhancing the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) and reduced the accumulation of H2O2 as compared with Cd alone. Application of S-nitrosoglutathione reductase (GSNOR) inhibitors dodecanoic acid (DA) in 100 μM SNP group brought in an extra elevation in S-nitrosylation level and further reinforced the effect of SNP. While the additions of 400 μM SNP and 400 μM SNP + 50 μM DA further elevated the S-nitrosylation level, it markedly weakened the alleviating effect against Cd toxicity as compared with the addition of 100 μM SNP. This phenomenon could be owing to excess consumption of glutathione (GSH) to form SNO under high S-nitrosylation level. Therefore, the present study indicates that S-nitrosylation is involved in the ameliorating effect of SNP against Cd toxicity. This involvement exhibited a concentration-dependent property.

Abstract 483: Mas/AT2 Receptor Deficient Mice Present A Pronounced Endothelial Dysfunction That Is Exclusively Mas-Related

The angiotensin type 2 (AT2) receptor and the angiotensin-(1-7) receptor MAS belong to the protective arm of the Renin Angiotensin System (RAS). They behave in a very similar way in terms of their physiological (tissue-protective) actions. Here we evaluate the endothelial function of Mas/AT2 double knockout mice (DKO) in two different backgrounds, C57BL/6 and FVB/N-C57BL/6 mixed background. Endothelial function in conscious mice was evaluated by measuring changes in mean arterial pressure (MAP) in response to bolus intra-aortic acetylcholine (ACh) and sodium nitroprusside (SNP) administration. The substances were given in 1μL per 10 g of body weight at the following doses: 25, 50, 100 ng/kg for ACh and 10 μg/kg for SNP. To correct the differences in vascular smooth muscle reactivity, the response to ACh was normalized by the SNP response. Our main results show that regarding the absolute response to ACh, Mas/AT2 DKO animals in both backgrounds had markedly decreased vasodilation response when compared with wild type (WT) over the dose range of 25 to 100 ng/kg (table 1). The MasKO animals had similar impairment of the vasodilatory response as the DKO mice when compared with WT animals, thus there was no statistical difference between the MasKO and DKO animals. No significant difference between the AT2KO and WT animals was observed in regard to the vasodilatory response to ACh. Normalization of ACh response with the SNP effect reinforced the observation that endothelium-dependent vascular reactivity was impaired. The evidence provided in this study suggests that the endothelial dysfunction observed in the Mas/AT2 DKO animals is exclusively due to the deletion of Mas.

Protective roles of nitric oxide on seed germination and seedling growth of rice (Oryza sativa L.) under cadmium stress

Nitric oxide (NO) is a bioactive molecule in plants which mediates a variety of physiological processes and responses to biotic and abiotic stresses including heavy metals. In the present study, the effects of exogenous NO donor sodium nitroprusside (SNP) on rice seed germination and seedlings growth were investigated under Cd stress and a possible mechanism was postulated. The results indicated that 100μM Cd significantly decreased rice seed germination index, vigor index, root and shoot lengths as well as fresh weight compared to control. Exogenous SNP dose-dependently attenuated the inhibition of rice seed germination and thereafter seedling growth caused by Cd. The promoting effect was most pronounced at 30μM SNP. Cd exposure caused oxidative stress by elevating hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents in root and shoot of rice seedlings. 30μM SNP counteracted partly Cd toxicity by reducing the H2O2 and MDA contents of Cd-exposed seedlings. Meanwhile, application of SNP markedly stimulated the activities of superoxide dismutases (SOD), ascorbate peroxidases (APX), guaiacol peroxidase (POD) and catalases (CAT) compared with Cd treatment alone, thereby indicating the enhancement of the antioxidative capacity in the root and shoot under Cd stress. In addition, addition of 30μM SNP increased accumulation of proline in both root and shoot. The Cd accumulation in seedlings was significant reduced by SNP, implicating that the protective role of SNP was responsible for preventing Cd accumulation. However, the effects of SNP were reverted by addition of cPTIO, a NO scavenger, suggesting the protective roles of SNP might be related to the induction of NO. Furthermore, K3Fe(CN)6 and NO3−/NO2− had no similar roles as SNP. Based on these results, it can be concluded that SNP exerted an advantageous effect on alleviating the inhibitory effect of Cd on rice seed germination and seedling growth, which might interact with NO.

Paraquat 유도 산화스트레스하의 배추 잎에서 Ascorbate-Glutathione 회로 효소의 활성도에 대한 산화질소 (Nitric oxide)의 효과

산화질소(nitric oxide: NO) 공여체인 <TEX>$100{\mu}M$</TEX> sodium nitroprusside (SNP)를 배추 잎에 전처리한 후 이어서 <TEX>$2{\mu}M$</TEX> paraquat (PQ)처리 시, PQ에 의해 유도된 산화적 손상에 대한 잎의 내성이 효과적으로 증진되었다. 24 시간 광 배양기간 동안 PQ 단독 처리구 잎에서는 생체량, 엽록소 및 단백질 함량이 현저하게 감소하였으나 PQ 노출 전에 3시간 SNP 전처리로 이들 잎 손상이 의미 있게 완화되었다. 게다가 PQ 처리에 기인된 malondialdehyde (MDA)와 <TEX>$H_2O_2$</TEX> 함량 증가도 SNP 전처리에 의해 유의하게 억제되었다. 잎에서 이들 PQ 독성에 대한 SNP의 방어효과와 관련하여 ascorbate-glutathione 회로 구성 효소의 활성도 변화를 조사하였다. PQ 단독 처리구에서 APX, DHAR 및 GR 효소 활성도는 배양 6시간후에 급격히 감소되어 대조구 잎과 비교 시 각각 대조구의 19%, 50%, 39% 수준의 활성도 값을 보였다. 그러나, 이들 효소 활성도 값 감소는 SNP 전처리에 의해 현저하게 억제되어 6시간 배양 후에 PQ 단독처리구 보다 각각 5배, 2배, 1.5배 높은 값을 나타내었다. 또한, 그 이후 24시간 배양 때까지 PQ 단독 처리구보다 계속 높은 활성도를 보이면서 점차로 감소하였다. 이들 결과로부터, PQ에 노출된 배추 잎에서 SNP 전처리에 의한 ascorbate-glutathione 회로의 활성화가 <TEX>$H_2O_2$</TEX>의 축적을 억제하며 그로인해 PQ에 의해 유도된 산화스트레스로부터 잎을 방어하는 것으로 생각되었다. 동시에 이 들 결과는 산화질소가 배추 잎에서 PQ 스트레스에 대한 항산화 방어자로서의 역할을 하는 것을 의미한다. Pretreatment of chinese cabbage leaves with <TEX>$100{\mu}M$</TEX> sodium nitroprusside (SNP), a nitric oxide (NO) donor, effectively improved their tolerance to subsequent <TEX>$2{\mu}M$</TEX> paraquat (PQ)-induced oxidative damage. The fresh weight, and chlorophyll and protein contents in primary leaves treated with PQ alone were noticeably reduced over 24 h light incubation. However, these leaf injury symptoms were significantly alleviated with <TEX>$100{\mu}M$</TEX> SNP pretreatment for 3 h prior to PQ exposure. In additions, the increase of the contents of malondialdehyde (MDA) and <TEX>$H_2O_2$</TEX> due to PQ exposure were significantly inhibited by SNP pretreatment. Together with the protective effects of SNP against PQ toxicity in leaves, the changes of ascorbate-glutathione cycle enzymes activities were examined. In the PQ alone treatment, the activities of APX, DHAR, and GR after 6 h incubation were rapidly reduced and showed 19%, 50% and 39% respectively, compared with those of the control. However, the decreases in these enzyme activities were significantly inhibited by SNP pretreatment. As a result, their activities were higher than those of PQ alone treatment by 5 times, 2 times, and 1.5 times, respectively, at 6 h incubation. Thereafter, these enzymes decrease their activities gradually showing high levels than those of PQ alone. Based on the above results, it can be assumed that the activation of ascorbate-glutathione cycle by SNP pretreatment in chinese cabbage leaves exposed to PQ can prevent <TEX>$H_2O_2$</TEX> accumulation, thereby leading to protection against PQ-induced oxidative stress. Also, these results indicate that NO acts as an protectant against PQ stress in the leaves of chinese cabbage.

Investigation of synergistic action between coronatine and nitric oxide in alleviating arsenic-induced toxicity in sweet basil seedlings

The phytotoxin coronatine (COR) is a jasmonic acid mimic produced by several pathovars of plant pathogen. In this study, we evaluated the protective effect of COR and nitric oxide (NO) against the toxicity of sodium arsenate in sweet basil (Ocimum basilicum L.). According to the statistical analysis, arsenic had a significant adverse effect on length and biomass of plants. Seedlings that pretreated with COR and sodium nitroprusside (SNP), significantly reversed fresh and dry lose and relative water content decay induced by the metalloid. The protective effects of COR and SNP were indicated by extent of lipid peroxidation, increase glutathione (GSH), ascorbate and thiol (–SH) content, promote antioxidant enzymes and reduce H2O2 content in basil seedlings. The present observation suggested that reduction of excess arsenic As-induced toxicity in O. basilicum by COR and NO is through the activation of enzymes involved in ROS detoxification (CAT, SOD, POD, APX, GR) and maintenance contents of molecular antioxidant (GSH, ascorbate, non-protein thiol and protein-thiol). Moreover, the results revealed a mutually amplifying reaction between COR and NO in reducing As-induced damages.

Kobophenol A inhibits sodium nitroprusside-induced cardiac H9c2 cell death through suppressing activation of JNK and preserving mitochondrial anti-apoptotic Bcl-2 and Mcl-1.

Sodium nitroprusside (SNP) releases nitric oxide (NO), a powerful vasodilator, and thus widely used in intensive care unit for treating hypertension emergency. However, cardiac toxicity after SNP administration is a clinical problem. For finding a natural compound that suppressing SNP-induced cardiac toxicity, we tested the protective potential of kobophenol A (Kob A), purified from the root of Caragana sinica, against the toxic effects of SNP. The severe cardiac H9c2 cell death was induced by SNP (2 mM) treatment. Kob A ameliorated SNP-induced cardiac H9c2 cell death, and this protective effect of Kob A may be related to the inhibition of c-Jun NH2-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase activation following SNP administration. In addition, the downregulation of cellular Bcl-2 and Mcl-1 levels by SNP exposure was strongly abrogated in the presence of Kob A. These biological properties of Kob A might provide insights into developing new cardioprotectant against SNP-induced cardiac cell death.

Sodium Nitroprusside inhibits HEK293 Cell Growth by cGMP-Dependent and Independent Mechanisms

The acute and chronic effects of sodium nitroprusside (SNP) are well characterized for vascular smooth muscle cells (VSMC). Stimulation of soluble guanylyl cyclase (sGC) gives a rapid elevation of intracellular cGMP levels and relaxation of VSMC. The antiproliferative effect of SNP needs days to develop. In the present study human embryonic kidney (HEK 293) cells were used to study the growth after repeated exposure to SNP. A dose-dependent antiproliferative effect was evident and after 5 days with an IC50 value of 108 μM. Cyclic GMP was able to mimic the antiproliferative effect of SNP on HEK293 cells. When cGMP (1000 μM) was added to the cell culture medium for 5 days the cell densities were reduced with 37% below baseline and cGMPin increased from 5.3 to 195 pmol/107cells. The interaction with the non-selective PDE (cyclic nucleotide phosphodiesterase) inhibitor 3-isobutyl-1-methylxanthine (IBMX) was tested after three days. IBMX alone (1000 μM) reduced cell densities with 48% and elevated cGMPin (from 5.2 to 9.3 pmol/107cells). The effect of 10 μM SNP was reinforced on proliferation (from 13% to 90%) and elevation of cGMP levels (from 7.6 to 13.5 pmol/107cells). A corresponding effect was observed after addition of 1000 μM cGMP and 1000 μM IBMX for 3 days. The antiproliferative effect of cGMP increased from 30% to 89% and the cGMPin increased from 240 to 480 pmol/107cells. However, additional mechanisms exist for the antiproliferative effect of SNP. One of these is the intracellular oxidative effect which includes production of S-nitrosoglutathione. The fall in ratios between GSH and GSSG from 260 to 85 after 100 μM SNP exposure is compatible with such a mechanism since cGMP (1000 μM) added to the culture medium did not change the ratio. This study shows that the antiproliferative effects of SNP on HEK293 cells are mediated through cGMP-dependent and cGMP-independent mechanisms. The concentration-dependent effects develop over time. HEK293 cells had an efficient efflux system for cGMP and the use of inside-out vesicles (IOVs) showed high affinity ATP-dependent cGMP transport with a Km value of 2.3 μM. The antiproliferative effect of SNP was correlated to cGMPex/in.

Application of sodium nitroprusside results in distinct antioxidant gene expression patterns in leaves of mature and senescing Medicago truncatula plants

Sodium nitroprusside (SNP) represents one of the most commonly used NO donors in biological sciences, which acts as a signal molecule in plants responsible for the regulation of the expression of many defense-related enzymes. This study attempts to provide novel insight into the effect of application of low (100 μΜ) and high (2.5 mM) concentrations of SNP on antioxidant gene expression (cAPX, GST, FeSOD, CAT, and AOX) in mature (40 day) and senescing (65 day) Medicago truncatula plants. Quantitative real-time RT-PCR suggests that low concentration of SNP applied in mature leaves leads to an overall induction of antioxidant gene expression, while increasing concentration results in suppression of these genes. Conversely, older plants demonstrate a much more variable regulation which appears to be time dependent. The observed transcriptional regulation pattern in mature M. truncatula plants comes in support of the previously documented protective or damaging effect of SNP depending on concentration applied, whereas senescing M. truncatula plants demonstrated a general suppression in antioxidant gene expression levels regardless of SNP concentration, indicative of reduced overall plant defense capacity against free radicals.

Beneficial effects of silymarin against nitric oxide-induced oxidative stress on cell characteristics of bovine oviduct epithelial cell and developmental ability of bovine IVF embryos

The antioxidative effects of silymarin were examined against nitric oxide-induced oxidative stress on cell characteristics of bovine oviduct epithelial cell (BOEC) and developmental rates of bovine in vitro fertilisation (IVF) embryos. The cell viability and morphology in BOEC which were treated with sodium nitroprusside (SNP) declined, as concentrations of SNP increase. The additions of silymarin 50, 100 and 200 µM into SNP 1000 µM increased the cell viability inhibited by SNP 1000 µM alone, but addition of silymarin 500 µM into SNP 1000 µM group did not recover the inhibitory effect of SNP 1000 µM (p<0.05). The levels of malondialdehyde (MDA), as the indicator of lipid peroxidation (LPO) in the treatments of SNPs increased with dose-dependant manners (p<0.05), whereas additions of silymarin 50, 100 and 200 µM into SNP 1000 µM significantly decreased MDA levels by 1.6, 1.4 and 1.3 folds of control (p<0.05). Antioxidant and Bcl-2 genes were expressed in control or SNP 1000 µM plus silymarin 200 µM treatment group, whereas pro-apoptotic genes (caspase-3 and Bax) were expressed only in SNP treatment groups. When bovine IVF embryos were co-cultured with BOEC supplemented with silymarin in the presence or absence of SNP, the development ability to blastocyst in 200 µM of silymarin alone was the highest among all treatments. These results suggest that silymarin has positive effects on cell characteristics such as viability, morphology and LPO of BOEC, and the increase of bovine IVF embryo development rate might be through antioxidative and anti-apoptotic actions.

Role of exogenous nitric oxide in alleviating iron deficiency-induced peanut chlorosis on calcareous soil

This study examined the effects of exogenous nitric oxide (NO) on physiological characteristics of peanut (Arachis hypogaea L.) growing on calcareous soil. Sodium nitroprusside (SNP), a NO donor, was root application (directly; slow-release bag; slow-release capsule; slow-release particle) and foliar application. The results showed that SNP application alleviated iron (Fe) deficiency-induced chlorosis, increased the yield of peanut and increased the Fe concentration in peanut grain. SNP, especially supplied by slow-release particle improved the available Fe in soil by reducing pH of soil and increasing available Fe of soil. Furthermore, SNP application significantly increased the H+-ATPase and Fe3+ reductase activities and increased the total Fe concentration in the leaves. Meanwhile, SNP application, especially foliar application enhanced the availability of Fe in the plant by significantly increasing the active Fe content and chlorophyll content in the leaves. In addition, SNP also increased the antioxidant activities, but decreased the superoxide anion (O2•−) generation rate and malondialdehyde content, which protected peanut against the Fe deficiency-induced oxidative stress. Therefore, these results support a physiological action of SNP on the availability, uptake and transport of Fe in the plant and foliar application SNP had the best effects in leaves and SNP supplied by slow-release particle had the best effects in roots. In addition, on the whole, the effects of SNP supplied by slow-release ways were better than directly supplied into the soil.

The mitochondrial uncoupler 2,4-dinitrophenol attenuates sodium nitroprusside-induced toxicity in Drosophila melanogaster: Potential involvement of free radicals

The toxicity of sodium nitroprusside (SNP) (an inducer of oxidative/nitrosative stress) and the attenuation of SNP effects by 2,4-dinitrophenol (DNP) (that induces mild uncoupling of respiration) were evaluated in the Drosophila melanogaster model system. Fly larvae were raised on food supplemented with 1.0mM SNP, 0.5 or 1.25mM DNP, or with mixtures 1.0mM SNP plus 0.5 or 1.25mM DNP. Food supplementation with SNP decreased larval viability and pupation height whereas supplementation with DNP substantially reversed these changes. Biochemical analyses of oxidative stress markers and activities of antioxidant and associated enzymes were carried out on 2-day-old flies emerged from control larvae and larvae fed on food supplemented with SNP, DNP, or SNP/DNP mixtures. Larval exposure to SNP lowered activities of aconitase, while the presence of DNP reduced the negative impact of SNP by raising aconitase activity back to near control levels. Larval treatment with SNP also elevated the contents of carbonyl protein, uric acid and low molecular mass thiols and produced higher activities of superoxide dismutase, glutathione S-transferase, glucose-6-phosphate dehydrogenase and thioredoxin reductase in adult flies. However, the presence of DNP in the food mixtures prevented SNP-induced changes in thioredoxin reductase and glucose-6-phosphate dehydrogenase activities, as well as uric acid and low-molecular-mass thiol content. The potential mechanisms by which DNP exerts protective effects against SNP toxicity are discussed.

Role of catecholamines and nitric oxide on pigment displacement of the chromatophores of freshwater snakehead teleost fish, Channa punctatus

We are reporting for the first time that the catecholamines (adrenaline and noradrenaline) inhibit the effect of nitric oxide (NO) on melanosome dispersion in freshly isolated scales of the freshwater snakehead fish, Channa punctatus. We studied the effect of NO and catecholamines on the pigment displacement by observing the changes in the melanophore index. The scales when treated with solution containing NO donor sodium nitroprusside (SNP) showed dispersion of melanosomes, whereas NO synthase blocker N-omega-Nitro-L-arginine suppresses this action of SNP. Treatment with adrenaline and noradrenaline on the isolated scales caused aggregation of melanosomes. Scales treated with solution containing catecholamines and SNP resulted in aggregation of melanosomes suggesting that catecholamines mask the effect of SNP. These results suggest that the catecholamines are inhibiting the effect of NO and causing the aggregation of the melanosomes may be via surface receptors.

Autologous Bone-Marrow Mesenchymal Stem Cell Implantation and Endothelial Function in a Rabbit Ischemic Limb Model

BackgroundThe purpose of this study was to determine whether autologous mesenchymal stem cells (MSCs) implantation improves endothelial dysfunction in a rabbit ischemic limb model.MethodsWe evaluated the effect of MSC implantation on limb blood flow (LBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and sodium nitroprusside (SNP), an endothelium-independent vasodilator, in rabbits with limb ischemia in which cultured MSCs were implanted (n = 20) or saline was injected as a control group (n = 20). LBF was measured using an electromagnetic flowmeter. A total of 106 MSCs were implanted into each ischemic limb.ResultsHistological sections of ischemic muscle showed that capillary index (capillary/muscle fiber) was greater in the MSC implantation group than in the control group. Laser Doppler blood perfusion index was significantly increased in the MSC implantation group compared with that in the control group. LBF response to ACh was greater in the MSC group than in the control group. After administration of NG-nitro-L-arginine, a nitric oxide synthase inhibitor, LBF response to ACh was similar in the MSC implantation group and control group. Vasodilatory effects of SNP in the two groups were similar.ConclusionsThese findings suggest that MSC implantation induces angiogenesis and augments endothelium-dependent vasodilation in a rabbit ischemic model through an increase in nitric oxide production.

Nitroprusside inhibits calcium‐induced impairment of red blood cell deformability

Red blood cell (RBC) deformation is critical for microvascular perfusion and oxygen delivery to tissues. Abnormalities in RBC deformability have been observed in aging, sickle cell disease, diabetes, and preeclampsia. Although nitric oxide (NO) prevents decreases in RBC deformability, the underlying mechanism is unknown. As an experimental model, we used ionophore A23187-mediated calcium influx in RBCs to reduce their deformability and investigated the role of NO donor sodium nitroprusside (SNP) and KCa3.1 (Gardos) channel blockers on RBC deformability (measured as elongation index [EI] by microfluidic ektacytometry). RBC intracellular Ca(2+) and extracellular K(+) were measured by inductively coupled plasma mass spectrometry and potassium ion selective electrode, respectively. SNP treatment of RBCs blocked the Ca(2+) (approx. 10 μmol/L)-induced decrease in RBC deformability (EI 0.34 ± 0.02 vs. 0.09 ± 0.01, control vs. Ca(2+) loaded, p < 0.001; and EI 0.37 ± 0.02 vs. 0.30 ± 0.01, SNP vs. SNP plus Ca(2+) loaded) as well as Ca(2+) influx and K(+) efflux. The SNP effect was similar to that observed after pharmacologic blockade of the KCa3.1 channel (with charybdotoxin or extracellular medium containing isotonic K(+) concentration). In RBCs from KCa3.1(-/-) mice, 10 μmol/L Ca(2+) loading did not decrease cellular deformability. A preliminary attempt to address the molecular mechanism of SNP protection suggests the involvement of cell surface thiols. Our results suggest that nitroprusside treatment of RBCs may protect them from intracellular calcium increase-mediated stiffness, which may occur during microvascular perfusion in diseased states, as well as during RBC storage.

Microcystin-LR-induced phytotoxicity in rice crown root is associated with the cross-talk between auxin and nitric oxide

Irrigation with cyanobacterial-blooming water containing microcystin-LR (MC-LR) poses threat to the growth of agricultural plants. Large amounts of rice (Oryza sativa) field in the middle part of China has been irrigating with cyanobacterial-blooming water. Nevertheless, the mechanism of MC-LR-induced phytotoxicity in the root of monocot rice remains unclear. In the present study, we demonstrate that MC-LR stress significantly inhibits the growth of rice root by impacting the morphogenesis rice crown root. MC-LR treatment results in the decrease in IAA (indole-3-acetic acid) concentration as well as the expression of CRL1 and WOX11 in rice roots. The application of NAA (1-naphthylacetic acid), an IAA homologue, is able to attenuate the inhibitory effect of MC-LR on rice root development. MC-LR treatment significantly inhibits OsNia1-dependent NO generation in rice roots. The application of NO donor SNP (sodium nitroprusside) is able to partially reverse the inhibitory effects of MC-LR on the growth of rice root and the expression of CRL1 and WOX11 by enhancing endogenous NO level in rice roots. The application of NO scavenger cPTIO [2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylinidazoline-1-oxyl-3-oxide] eliminates the effects of SNP. Treatment with NAA stimulates the generation of endogenous NO in MC-LR-treated rice roots. Treatment with NO scavenger cPTIO abolishes the ameliorated effect of NAA on MC-LR-induced growth inhibition of rice root. Treatment with SNP enhanced IAA concentration in MC-LR-treated rice roots. Altogether, our data suggest that NO acts both downstream and upstream of auxin in regulating rice root morphogenesis under MC-LR stress.

Ilk conditional deletion in adult animals increases cyclic GMP-dependent vasorelaxation

Integrin-linked kinase (ILK) regulates proliferation, differentiation, cell adhesion, and motility in many cell types and has been related to cancer progression, fibrosis, and vascular diseases. We designed the present study to directly explore the effect of ILK deletion on the regulation of vascular tone through the soluble guanylate cyclase (sGC) /protein kinase G (PKG) pathway in healthy adult mice. Experiments were carried out using a tamoxifen-inducible CRE-LOX system to conditionally delete the ILK gene in adult mice. Mice lacking ILK expression (cKO) presented increased vascular content and increased activity of sGC and PKG, resulting in a more intense vasodilatory response to a single dose of a nitric oxide (NO) donor [sodium nitroprusside (SNP)] or PKG agonist [8-bromoguanosine 3',5'-cyclic monophosphate sodium salt (8-Br)]. Five minutes after SNP or 8-Br administration the reduction in the systolic arterial pressure was enhanced in cKO mice (SNP WT: -7.4 ± 1.2 mmHG; SNP cKO: -14.0 ± 2.5; 8-Br WT: -2.9 ± 1.5 mmHG; 8-Br cKO: -10.0 ± 3.4 mmHG). ILK deletion restored the vascular response to SNP after chronic oral nitrite administration. In addition, ILK deletion also increased hypotensive SNP effect in angiotensin II-treated animals, suggesting a role for ILK in basal and pathological states. Deletion of ILK in adult animals increased the vascular response to NO. These findings show, for the first time, a requirement for ILK in regulating sGC-PKG expression in vivo.