Synthesis of 3'- and 5'-nitrooxy pyrimidine nucleoside nitrate esters: "nitric oxide donor" agents for evaluation as anticancer and antiviral agents

A group of 3'-O-nitro-2'-deoxyuridines, 3'-O-nitro-2'-deoxycytidines, and 5'-O-nitro-2'-deoxyuridines possessing a variety of substituents (H, Me, F, I) at the C-5 position were synthesized for evaluation as anticancer/antiviral agents that have the ability to concomitantly release cytotoxic nitric oxide (*NO). Although these compounds generally released a greater percent of *NO than the reference drug isosorbide dinitrate upon incubation in the presence of l-cysteine, or serum, their cytotoxicity (CC(50) = 10(-3) to 10(-6) M range) was comparable to 5-iodo-2'-deoxyuridine, but weaker than 5-fluoro-2'-deoxyuridine, against a variety of cancer cell lines. No differences in cytotoxicity against nontransfected (KBALB, 143B), and the corresponding transfected (KBALB-STK, 143B-LTK) cancer cell lines possessing the herpes simplex virus type 1 (HSV-1) thymidine kinase gene (TK(+)) were observed, indicating that expression of the viral TK enzyme did not provide a gene therapeutic effect. These nitrate esters were inactive antiviral agents except for 5-iodo-3'-O-nitro-2'-deoxyuridine that showed modest activity against HSV-1, HSV-2, and vaccinia virus.     

Analysis of agonist-evoked nitric oxide release from human endothelial cells: role of superoxide anion

1. Dichlorofluorescein oxidation and electrochemical monitoring of in situ nitric oxide (NO) release from cultured human endothelial cells reveals that agonists such as thrombin and histamine simultaneously stimulate transient superoxide production. 2. The duration of *NO release was increased only in the simultaneous presence of extracellular L-arginine and exogenous superoxide dismutase. In contrast, the inhibition of membrane reduced nicotinamide adenine dinucleotide (phosphate) oxidases, the major source of *O2- in endothelial cells, did not prolong *NO release, although extracellular L-arginine was also present. Comparison of these two experimental conditions suggested that H2O2 was involved in the extension of the *NO signal. 3. The present study demonstrates that, in the absence of external L-arginine, *O2- production does not constitute the major pathway controlling the duration of agonist-induced *NO signal. These results suggest that L-arginine and H2O2 act jointly to maintain nitric oxide synthase in an activated form.     

Scavenging effects of natural phenols on oxidizing intermediates of peroxynitrite

Most of peroxynitrite (ONOO-/ONOOH) is formed via the diffusion-limited reaction between nitric oxide and superoxide. In biological systems, the decomposition of ONOO- yields 30-35% of carbonate radical (CO3*-) and nitrogen dioxide (NO2*), which are strongly oxidizing intermediates and are suggested to take a part of the responsibility for the toxicity of nitric oxide (NO*) or ONOO-. Therefore, the current study focuses on the scavenging activities of phenols toward CO3*- and NO2* to protect biomolecules from damage caused by NO* or ONOO- using the technique of pulse radiolysis. From the build-up kinetic of the phenoxyl radicals and the decay kinetic of CO3*- radical, the rate constants of scavenging reactions were determined to be 1.9-3.4 x 10(8) M(-1) x s(-1) and 0.11-1.9 x 10(8) M(-1) x s(-1) for CO3*- and NO2* respectively. The results indicated that the tested phenols are the efficient scavengers of CO3*- and NO2*.     

Novel roles for palmitoylation of Ras in IL-1 beta-induced nitric oxide release and caspase 3 activation in insulin-secreting beta cells

We recently demonstrated that functional inactivation of H-Ras results in significant reduction in interleukin 1 beta (IL-1 beta)-mediated effects on isolated beta cells. Since palmitoylation of Ras has been implicated in its membrane targeting, we examined the contributory roles of palmitoylation of Ras in IL-1 beta-induced nitric oxide (NO) release and subsequent activation of caspases. Preincubation of HIT-T15 or INS-1 cells with cerulenin (CER, 134 microM; 3 hr), an inhibitor of protein palmitoylation, significantly reduced (-95%) IL-1 beta-induced NO release from these cells. 2-Bromopalmitate, a structurally distinct inhibitor of protein palmitoylation, but not 2-hydroxymyristic acid, an inhibitor of protein myristoylation, also reduced (-67%) IL-1 beta-induced NO release from HIT cells. IL-induced inducible nitric oxide synthase gene expression was markedly attenuated by CER. Further, CER markedly reduced incorporation of [3H]palmitate into H-Ras and caused significant accumulation of Ras in the cytosolic fraction. CER-treatment also prevented IL-1 beta-induced activation of caspase 3 in these cells. Moreover, N-monomethyl-L-arginine, a known inhibitor of inducible nitric oxide synthase, markedly inhibited IL-induced activation of caspase 3, thus establishing a link between IL-induced NO release and caspase 3 activation. Depletion of membrane-bound cholesterol using methyl-beta-cyclodextrin, which also disrupts caveolar organization within the plasma membrane, abolished IL-1 beta-induced NO release suggesting that IL-1 beta-mediated Ras-dependent signaling in these cells involves the intermediacy of caveolae and their key constituents (e.g. caveolin-1) in isolated beta cells. Confocal light microscopic evidence indicated significant colocalization of Ras with caveolin-1. Taken together, our data provide the first evidence to indicate that palmitoylation of Ras is essential for IL-1 beta-induced cytotoxic effects on the islet beta cell.     

Establishment and use of a cell line expressing HSV-1 thymidine kinase to characterize viral thymidine kinase-dependent drug-resistance

To understand the mechanisms of antiviral drug resistance and to have a system to examine the cytotoxicity of herpes simplex virus type 1 (HSV-1) inhibitors that are thymidine kinase (TK)-dependent, we have constructed a plasmid pFTK1 by inserting a DNA fragment containing the TK gene of HSV-1 strain F into the eukaryotic expression vector pcDNA3.1/His A. TK-deficient 143B cells were transfected with this vector and neomycin-resistant cells were selected. Cell survival in HAT medium and TK activity of the cell lysates were examined to ascertain HSV-1 TK expression. A cell line expressing the viral TK gene, FTK143B (FTK), was established and used for characterization of two laboratory-derived TK-deficient drug-resistant HSV-1 mutants of strain F. The antiviral activities of several drugs, mostly nucleoside analogues, were compared in the Vero, 143B and FTK cell culture systems. We showed that both mutant viruses lost their resistance to acyclovir and to other HSV-1 TK-dependent compounds in FTK cells but not in Vero and 143B cells. Significantly increased cytotoxicity of ganciclovir and (E)-5-(2-bromovinyl)-2'-deoxyuridine was also observed in the FTK cells. This HSV-1 TK gene-transfected cell model is a useful tool to rapidly determine HSV-1 drug resistance at the viral TK level.     

Delivery method, target gene structure, and growth properties of target cells impact mutagenic responses to reactive nitrogen and oxygen species

Dysregulated production of nitric oxide (NO?) and reactive oxygen species (ROS) by inflammatory cells in vivo may contribute to mutagenesis and carcinogenesis. Here, we compare cytotoxicity and mutagenicity induced by NO? and ROS in TK6 and AS52 cells, delivered by two methods: a well-characterized delivery system and a novel adaptation of a system for coculture. When exposed to preformed NO?, a cumulative dose of 620 μM min reduced the viability of TK6 cells at 24 h to 36% and increased mutation frequencies in the HPRT and TK1 genes to 7.7 × 10?? (p < 0.05) and 24.8 × 10?? (p < 0.01), 2.7- and 3.7-fold higher than background, respectively. In AS52 cells, cumulative doses of 1700 and 3700 μM min reduced viability to 49 and 22%, respectively, and increased the mutation frequency 10.2- and 14.6-fold higher than the argon control (132 × 10?? and 190 × 10??, respectively). These data show that TK6 cells were more sensitive than AS52 cells to killing by NO?. However, the two cell lines were very similar in relative susceptibility to mutagenesis; on the basis of fold increases in MF, average relative sensitivity values [(MF(exp)/MF(control))/cumulative NO? dose] were 5.16 × 10?3 and 4.97 × 10?3 μM?1 min?1 for TK6 cells and AS52 cells, respectively. When AS52 cells were exposed to reactive species generated by activated macrophages in the coculture system, cell killing was greatly reduced by the addition of NMA to the culture medium and was completely abrogated by combined additions of NMA and the superoxide scavenger Tiron, indicating the relative importance of NO? to loss of viability. Exposure in the coculture system for 48 h increased mutation frequency in the gpt gene by more than 9-fold, and NMA plus Tiron again completely prevented the response. Molecular analysis of gpt mutants induced by preformed NO? or by activated macrophages revealed that both doubled the frequency of gene inactivation (40% in induced vs 20% in spontaneous mutants). Sequencing showed that base-substitution mutations dominated the spectra, with transversions (30-40%) outnumbering transitions (10-20%). Virtually all mutations took place at guanine sites in the gene. G:C to T:A transversions accounted for about 30% of both spontaneous and induced mutations; G:C to A:T transitions amounted to 10-20% of mutants; insertions, small deletions, and multiple mutations were present at frequencies of 0-10%. Taken together, these results indicate that cell type and proximity to generator cells are critical determinants of cytotoxic and genotoxic responses induced by NO? and reactive species produced by activated macrophages.     

Nitric oxide-donating properties of mesoionic 3-aryl substituted oxatriazole-5-imine derivatives.

1. The nitric oxide (NO)-releasing properties of two new mesoionic 3-aryl substituted oxatriazole-5-imine derivatives (GEA 3162 and GEA 3175) were characterized and compared with the known NO-donors 3-morpholino-sydnonimine (SIN-1) and S-nitroso-N-acetylpenicillamine (SNAP). 2. GEA 3162, GEA 3175, SIN-1 and SNAP inhibited adenosine 5'-diphosphate-induced platelet aggregation (IC50 values 0.18, 0.39, 3.73 and 2.12 microM, respectively). All four compounds induced a dose-dependent and more than 4 fold increase in cyclic GMP in platelets. The increase in cyclic GMP concentration was potentiated more than 1.5 fold by a phosphodiesterase inhibitor, zaprinast (10 microM) and inhibited 38-97% by oxyhaemoglobin (10-45 microM). 3. All of the four compounds studied converted oxyhaemoglobin to methaemoglobin and formed a paramagnetic NO-haemoglobin complex. All but GEA 3175 formed nitrite and nitrate in phosphate buffer. During a 40 min incubation, GEA 3162, SIN-1 and SNAP (100 microM) produced 50-70 microM NO2- + NO3- as determined by high performance liquid chromatography. The release of NO and NO2 by GEA 3175 was increased 140 fold in the presence of human plasma (0.14 and 19.7 ppb in the absence and presence of 1% human plasma, respectively) as analyzed by ozone chemiluminescence. 4. The results suggest that the mesoionic 3-aryl substituted oxatriazole-5-imine derivatives GEA 3162 and GEA 3175 as well as SIN-1 and SNAP release nitric oxide.     

丹酚酸B对β-淀粉样蛋白介导原代培养皮层神经元毒性的保护作用

目的　观察一氧化氮(NO)在谷氨酸(Glu),β-淀粉样蛋白［β-AP(1-40)］引起神经细胞损伤中的作用以及丹酚酸B(Sal B)对β-AP(1-40)引起的神经细胞损伤保护作用。方法　原代培养大鼠皮层神经元,建立了硝普钠(SNP),Glu,β-AP(1-40)等3种损伤模型,用形态学观察、MTT比色法、Griess法分别测定神经元活力,培养液中乳酸脱氢酶(LDH)漏出和NO释放。结果　Glu和β-AP(1-40)可以引起神经元NO的释放增加,造成神经毒性。nNOS在Glu的毒性中起重要作用,iNOS可能在Aβ_1-40的毒性中起作用。Sal B能显著增加细胞活力,降低LDH释放率,并剂量依赖地减少NO释放。 结论　NO介导了Glu和β-AP(1-40)的毒性,Sal B可以通过减少NO释放,改善β-AP(1-40)的毒性作用。     

Synthesis and Biological Investigations of Nitric Oxide Releasing Nateglinide and Meglitinide Type II Antidiabetic Prodrugs: In-Vivo Antihyperglycemic Activities and Blood Pressure Lowering Studies

A new group of hybrid nitric oxide-releasing type II antidiabetic drugs possessing a 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (13 and 18), 1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (14 and 19), or nitrooxyethyl (15 and 20) moiety attached to the carboxylic acid group of the type II antidiabetic drugs nateglinide and meglitinide were synthesized. These prodrugs, based on the beneficial properties of nitric oxide (NO), were designed to reduce the risk of adverse cardiovascular events in diabetic patients. Ester prodrugs (13-15 and 18-20) exhibited appreciable oral antihyperglycemic activity comparable to the parent drugs in nonfasted diabetic rats. Systolic and diastolic blood pressure profiles validated the beneficial hypotensive properties of these prodrugs. These prodrugs released NO (1.3-72.2% range) upon incubation with either phosphate buffer solution at pH 7.4 or in the presence of serum. This new type of hybrid NO donor prodrug represents an attractive approach for the rational design of type II antidiabetic drugs with a reduced risk of contraindicated cardiovascular events.     

Potent anti-inflammatory activity of 3-aminovinylphosphonates as inhibitors of reactive oxygen intermediates, nitric oxides generation, and tumor necrosis factor-alpha release

Two 3-aminoalkenylphosphonate compounds 1, 2, and a hydroxyl derivative, 2-(3-hydroxy-3-phenylpropyl)hex-1-enylphosphonate 3, recently synthesized in our lab, have been evaluated for their ability to modulate the production of reactive oxygen intermediates, nitric oxide (NO) and tumor necrosis factor (TNF-alpha) by murine macrophages. We found that all three molecules suppressed generation of reactive oxygen intermediates, NO, and TNF-alpha. However, although 2-(3-hydroxy-3-phenylpropyl)hex-1-enylphosphonate 3 possessed higher activity in suppression of reactive oxygen intermediates and nitric oxide compared to 3-aminoalkenylphosphonates 1 and 2, it showed less activity in the inhibition of tumor necrosis factor release.     

Akt-dependent phosphorylation of serine 1179 and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 cooperatively mediate activation of the endothelial nitric-oxide synthase by hydrogen peroxide

Hydrogen peroxide mediates vasodilation, but the mechanisms responsible for this process remain undefined. We examined the effect of H(2)O(2) on nitric oxide (NO*) production and the signaling events involved. NO* release from bovine aortic endothelial cells was detected with an NO*-specific microelectrode. The addition of H(2)O(2) caused a potent dose-dependent increase in NO* production. This was partially Ca(2+)-dependent because BAPTA/AM reduced NO* production at low (<50 microM) but not high (>100 microM) concentrations of H(2)O(2). Phosphatidylinositol (PI) 3-kinase inhibition [with wortmannin or 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride], infection with a dominant-negative mutant of Akt, or mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 (MEK/ERK1/2) inhibition (with PD98059 or U0126) partially attenuated, whereas inhibition of both PI 3-kinase and MEK1/2 abolished H(2)O(2)-dependent NO* production. ERK1/2 seemed necessary for NO* production early (<5 min) after H(2)O(2) addition, whereas PI 3-kinase/Akt was more important at later time points. Phosphorylation of endothelial nitric-oxide synthase (eNOS) at serine 1179 was observed >10 min after the addition of H(2)O(2), and this was prevented by wortmannin but not by PD98059. c-Src family tyrosine kinase(s) was found to be upstream of H(2)O(2)-dependent Akt and eNOS serine 1179 phosphorylation and subsequent NO* production. In summary, H(2)O(2) causes endothelial NO* release mediated by cooperative effects between PI 3-kinase/Akt-dependent eNOS serine 1179 phosphorylation and activation of MEK/ERK1/2. This may represent an acute cellular adaptation to an increase in oxidant stress.     

Inducible nitric oxide synthase catalyzes ethanol oxidation to alpha-hydroxyethyl radical and acetaldehyde

The physiologic function of nitric oxide synthases, independent of the isozyme, is well established, metabolizing L-arginine to L-citrulline and nitric oxide (NO). This enzyme can also transfer electrons to O2, affording superoxide (O2*-) and hydrogen peroxide (H2O2). We have demonstrated that NOS1, in the presence of L-arginine, can biotransform ethanol (EtOH) to alpha-hydroxyethyl radical (CH3*CHOH). We now report that a competent NOS2 with l-arginine can, like NOS1, oxidize EtOH to CH3*CHOH. Once this free radical is formed, it is metabolized to acetaldehyde as shown by LC-ESI-MS/MS and HPLC analysis. These observations suggest that NOS2 can behave similarly to cytochrome P-450 in the catalysis of acetaldehyde formation from ethanol via the generation of alpha-hydroxyethyl radical when L-arginine is present.     

Naphthazarin and methylnaphthazarin cause vascular dysfunction by impairment of endothelium-derived nitric oxide and increased superoxide anion generation.

The effects of the naphthoquinone analogue, naphthazarin (Nap), and its derivative, methylnaphthazarin (MetNap), on vascular reactivity were studied using isolated rat aortic rings and human umbilical vein endothelial cells (HUVECs). In this study, we determined vessel tension, nitric oxide (NO) formation, endothelial nitric oxide synthase (eNOS) activity, eNOS protein expression, and superoxide anion (O2*-) generation in an effort to evaluate the effect of Nap and MetNap on the impairment of the NO-mediated pathway. Lower concentrations of Nap (0.01-1 microM) and MetNap (1-10 microM) concentration-dependently enhanced phenylephrine (PE)-induced vasocontraction and abrogated acetylcholine (ACh)-induced vasorelaxation in an endothelium-dependent manner. On HUVECs, both Nap and MetNap concentration-dependently inhibited NO formation induced by A23187, and also partially inhibited nitric oxide synthase (NOS) activity. eNOS protein expression by HUVECs was not affected by treatment with Nap or MetNap, even within 24h. These data suggest that Nap and MetNap might act as inhibitors of nitric oxide synthesis in the endothelium. In addition, Nap and MetNap were also shown to generate O2*- on HUVECs with short-term treatment. We concluded that Nap and MetNap inhibited agonist-induced relaxation and induced vasocontraction in an endothelium-dependent manner, and these effects might have been due to modification of the NO content by inhibition of NOS activity and bioinactivation through O2*- generation.     

Beta3-adrenergic stimulation in the human heart: signal transduction, functional implications and therapeutic perspectives

Next to beta1- and beta2-adrenoceptors, a third beta-adrenoceptor population is expressed in the human heart, the beta3-adrenoceptor. In mammalian ventricular myocytes, beta3-adrenergic stimulation leads to a decrease in contractility via a release of nitric oxide (NO). Recently, different molecular mechanisms of beta3-adrenergic activation of endothelial nitric oxide synthase (eNOS) have been uncovered in cardiac myocytes. In the non-failing and especially the failing heart, beta3-adrenergic stimulation may offer protection against excessive catecholaminergic beta1-adrenoceptor stimulation. In this context, the beta3-adrenoceptor is discussed as a novel target for the pharmacological therapy of heart failure.     

Cardiovascular effects of peroxynitrite

1. Peroxynitrite (PN) is formed in biological systems from the reaction of nitric oxide (*NO) with superoxide (O2(-)*) and both exist as free radicals. By itself, PN is not a free radical, but it can generate nitrogen dioxide (*NO2) and carbonate radical (CO3(-)*) upon reaction with CO2. 2. The reaction of CO2 constitutes a major pathway for the disposition of PN produced in vivo and this is based on the rapid reaction of PN anion with CO2 and the availability of CO2 in both intra- and extracellular fluids. The free radicals *NO2 and CO3(-)*, in combination with *NO, generated from nitric oxide synthase, can bring about oxidation of critical biological targets resulting in tissue injury. However, the reactions of *NO2, CO3(-)* and *NO with carbohydrates, protein and non-protein thiols, phenols, indoles and uric acid could result in the formation of a number of nitration and nitrosation products in the vasculature. These products serve as long-acting *NO donors and, therefore, contribute to vasorelaxant properties, protective effects on the heart, inhibition of leucocyte-endothelial cell interactions and reduction of reperfusion injury. 3. Herein, we review the chemistry of PN, the observations that the effects of PN could be mediated by formation of an *NO donor-like substance and review the physiological and beneficial effects of PN.     

Novel nonsteroidal antiinflammatory drugs possessing a nitric oxide donor diazen-1-ium-1,2-diolate moiety: design, synthesis, biological evaluation, and nitric oxide release studies

A novel group of hybrid nitric oxide-releasing nonsteroidal antiinflammatory drugs ((*)NO-NSAIDs) possessing a 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (11, 13, 15) or 1-(N,N-dimethylamino)diazen-1-ium-1,2-diolate (12, 14, 16) moiety attached via a one-carbon methylene spacer to the carboxylic acid group of the traditional NSAIDs aspirin, ibuprofen, and indomethacin were synthesized. Although none of these ester prodrugs (11-16) exhibited in vitro cyclooxygenase (COX) inhibitory activity against the COX-1 and COX-2 isozymes (IC(50) > 100 microM), all of the compounds (11-16) significantly decreased carrageenan-induced rat paw edema. In this regard, the ester prodrugs 11-16 showed equipotent antiinflammatory activities in vivo to that of the parent drugs aspirin, ibuprofen, and indomethacin. All of the compounds released nitric oxide upon incubation with either phosphate buffer solution at pH 7.4 (14-16% range) or porcine liver esterase (16-19% range), but the percentage of (*)NO released was up to sixfold higher (93%) when these ester prodrugs were incubated with guinea pig serum. These incubation studies suggest that both (*)NO and the parent NSAID would be released upon in vivo cleavage by nonspecific serum esterases. The simultaneous release of aspirin and nitric oxide from the (*)NO-aspirin prodrugs constitutes a potentially beneficial property for the prophylactic prevention of thrombus formation and adverse cardiovascular events such as stroke and myocardial infarction. The data acquired in an in vivo ulcer index (UI) assay showed that for this group of ester prodrugs, particularly the (*)NO-aspirins (11, 12) and (*)NO-ibuprofens (13, 14), no lesions were observed (UI = 0) when compared to the parent drugs aspirin (UI = 57, 250 mg/kg po dose), ibuprofen (UI = 45, 250 mg/kg po dose), or indomethacin (UI = 34, 30 mg/kg po dose) at equivalent doses. Accordingly, these hybrid (*)NO-NSAID prodrugs possessing a diazen-1-ium-1,2-diolate moiety, represent a new approach for the rational design of antiinflammatory drugs with reduced gastric ulcerogenicity.     

Syntheses, calcium channel agonist-antagonist modulation activities, and nitric oxide release studies of nitrooxyalkyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate racemates, enantiomers, and diastereomers

A novel group of hybrid calcium channel (CC) modulators was prepared where the isopropyl ester moiety of isopropyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate (PN 202-791) was replaced by a variety of nitric oxide (*NO) donor nitrooxyalkyl ester substituents. Enantiomers, or diastereomers, having the (R)-configuration at the C-4 position of the 1,4-dihydropyridine ring (1,4-DHP) exhibited more potent in vitro CC antagonist activity on guinea pig ileum longitudinal smooth muscle (GPILSM) than compounds having the (4S)-configuration. None of the nitrooxyalkyl compounds exhibited a contraindicated CC agonist effect on GPILSM that would cause smooth muscle contraction. Structure-activity studies showed the enantiomers having the (S)-configuration at the C-4 position of the 1,4-DHP ring or diastereomers having the a (4S)-configuration at the C-4 position of the 1,4-DHP ring in conjunction with a (1R-)-1-methyl-2-nitrooxyethyl ester substituent exhibited the most potent cardiac CC agonist (positive inotropic) activity on guinea pig left atrium (GPLA). This class of compounds releases *NO in vitro that is enhanced by the presence of a thiol such as N-acetylcysteamine. The novel *NO donor (-)-(S,R)-1-methyl-2-nitrooxyethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2,1,3-benzoxadiazol-4-yl)pyridine-5-carboxylate [(-)-(S,R)-38], which acts as a dual cardioselective calcium channel agonist (GPLA)/smooth muscle selective calciumchannel antagonist (GPILSM), is a useful lead compound for drug discovery targeted to the treatment of congestive heart failure, and it provides a useful research probe to study the structure-function relationship of calcium channels.     

丁基苯酞对原代培养胎大鼠皮层神经细胞外液NO及胞浆内cGMP水平的影响

用分光光度法和放射免疫分析法分别检测NO及cGMP水平,同时观察l-丁基苯酞(l-NBP)和d-丁基苯酞(d-NBP)对原代培养的胎大鼠皮层神经细胞外液NO及胞浆内cGMP水平的影响。结果表明,d-NBP(0.1～100μmol·L^-1)对低糖低氧条件下或含N-甲基-D-门冬氨酸(NMDA)或含KCl的培养基中皮层神经细胞外液NO及细胞内cGMP水平明显升高,而l-NBP(0.1～100μmol·L^-1)则能明显降低NO和cGMP水平。提示:d-NBP和l-NBP对低糖低氧,NMDA或KCl诱导的NO释放和cGMP生成有相反的作用。