Effects of inhibitors of arachidonic acid metabolism on calcium uptake and catecholamine release in cultured adrenal chromaffin cells

The possibility that arachidonic acid metabolism is involved in the secretory process in cultured adrenal chromaffin cells was investigated by studying the effects of lipoxygenase inhibitors and cyclooxygenase inhibitors on 45Ca2+ uptake and catecholamine release. Lipoxygenase inhibitors, which have different chemical structures, such as nordihydroguaiaretic acid (NDGA), 3-amino-1-(3-trifluoromethylphenyl)-2-pyrazoline (BW755C) and 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA861) all prevented the catecholamine release evoked by carbamylcholine and high K+. In contrast, cyclooxygenase inhibitors, such as aspirin and indomethacin failed to inhibit the carbamylcholine-evoked catecholamine release. Lipoxygenase inhibitors also inhibited 45Ca2+ uptake into the cells stimulated by carbamylcholine and high K+. Lipoxygenase inhibitors inhibited 45Ca2+ uptake and catecholamine release with similar potency. Slightly higher concentrations of lipoxygenase inhibitors were required to inhibit high K+-evoked effects compared to those evoked by carbamylcholine. The inhibitory effects of these inhibitors on carbamylcholine-evoked catecholamine release was different in its nature from the inhibitory effect of verapamil, a blocker of the Ca2+ channel, and was not due to a competitive antagonism at cholinergic receptor site. Moreover, these lipoxygenase inhibitors did not inhibit the binding of [3H]nitrendipine to chromaffin cell homogenate. The data suggest that lipoxygenase inhibitors prevent the catecholamine release from cultured adrenal chromaffin cells by blocking Ca2+ uptake. It might be possible that lipoxygenase product(s) is involved in the Ca2+ translocation system in these cells.     

Effects of 8-(N-N-diethylamino)octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8) on skinned myocardial fibres of the rat: reversible inhibition of calcium release from the sarcoplasmic reticulum

The effects of 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8), which is reported to inhibit the release of intracellularly stored Ca²⁺ in skeletal and smooth muscles, were examined in ventricular myocardia of the adult rat. In skinned papillary muscle fibres with functional sarcoplasmic reticulum (SR) preserved, application of 100 or 300 M TMB-8 during the Ca²⁺ loading period had no significant effect on the peak tension of subsequent caffeine-induced contraction, but when applied during exposure to caffeine, concentration-dependent reduction of the peak tension was observed. At 1000 M, TMB-8 reduced the peak tension of caffeine-induced contraction when applied either during Ca²⁺ loading or during exposure to caffeine. TMB-8 had no substantial influence on the Ca⁺-tension of skinned fibres without functional SR. In isolated papillary muscle preparations, TMB-8 prolonged the action potential duration and decreased the maximum rate of rise of potential, leading to abolition of contraction at 100 M. In conclusion, TMB-8 may be a useful pharmacological tool for inhibiting Ca²⁺ release from SR, but only in skinned myocardial preparations.     

Pharmacological evaluation of a new Ca2+ antagonist, 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8): studies in smooth muscles

The pharmacology of 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8) has been studied using guinea pig ileum and vas deferens preparations. TMB-8 inhibited responses to drugs that excite specific receptors (acetylcholine and norepinephrine) as well as to agents whose actions are not mediated via specific receptors (KCl and BaCl₂) with ID₅₀'s of 3.8 × 10^?6 to 1 × 10^?4 M. TMB-8 inhibited responses to acetylcholine, norepinephrine, nicotine, dimethylphenylpiperazinium and KCl in an insurmountable manner in the guinea pig ileum, while responses to BaCl₂ were inhibited in a competitive manner. Increasing Ca²⁺ concentrations of the bathing medium from 1.35 to 5.40 mM effectively antagonized the TMB-8 inhibition of responses to KCl in the guinea pig ileum and vas deferens preparations. These results indicate that TMB-8 may produce its inhibitory effects in smooth muscle by interfering with the availability of Ca²⁺ for muscle contraction by blocking the Ca²⁺ release from intracellular bound stores.     

1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基)丙烷盐酸盐对肥厚心肌DNA含量和培养心肌细胞DNA合成的影响

为研究1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基) 丙烷盐酸盐(DDPH)对心肌肥厚大鼠左室组织 DNA 含量有无逆转作用, 用部分狭窄腹主动脉的方法建 立心肌肥厚的模型. 术后wk4开始给药, 连续8 wk, 左室心肌切片并进行 Feulgen染色, 用 TJTY-300 图像分析系统对DNA进行相对定量, 发现肥厚组平均吸光度为0.089, 是对照组的1.43倍,而二个给药组分别为0.079和0.071, 明显低于肥厚组, 但仍高于对照组(P<0.05), 说明DDPH对肥厚心肌的 DNA 含量有一定的逆转作用. 为进一步研 究 DDPH 能否抑制去甲肾上腺素 (NE) 致培养乳鼠心肌细胞DNA合成的作用, 体外培养乳鼠心肌细胞, 实验分 6 组: (1) 对照组; (2) NE组; (3) DDPH 1.0 μmol·L^-1组; (4) DDPH 10 μmol·L^-1组; (5) 哌唑嗪(Pra) 1.0 μmol·L^-1组; 6) Pra 10 μmol·L^-1组. 每孔加［³H］TdR 37 Bq, 3 h后测 cpm 值, 发现 NE 组为对照组的3.1倍,而 DDPH 及 Pra 组均减少 cpm 值 (P<0.01), 且 Pra 组作用更明显, 二个高剂量组与对照组无显著差异, 结果说明 DDPH 可以抑制 NE 诱导的乳鼠心肌细胞 DNA 合成的增加.     

钙拮抗剂TMB-8对培养牛大脑中动脉内皮细胞[Ca2+]i和一氧化氮释放的影响

目的旨在观察TMB-8对血管内皮细胞[Ca²⁺]i水平和NO释放的影响,探讨扩张脑血管的机制。用AR-CM-MIC阳离子测定系统,测量单个细胞内游离钙浓度([Ca²⁺]i),用血红蛋白法测量一氧化氮(NO)的释放。结果表明,在细胞外钙浓度为1.3mmol·L^-1时,TMB-8 12.5及25.0μmol·L^-1对静息[Ca²⁺]i和甲基血红蛋白ΔE无明显影响,而50及100μmol·L^-1时可升高静息[Ca²⁺]i和甲基血红蛋白ΔE。表明TMB-850及100μmol·L^-1升高脑血管内皮[Ca²⁺]i,激活NO合酶,促进NO合成和释放,这可能是其扩张脑血管的重要机制之一。     

1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基)丙烷盐酸盐对内皮素促血管平滑肌细胞增殖及癌基因表达的影响

采用内皮素-1(ET-1 0.1 μmol·L^-1)建立培养的血管平滑肌细胞增殖模型，用［³H］胸腺嘧啶核苷(［³H］TdR)参入法, 流式细胞术, 免疫细胞化学及Northern blot方法, 观察了1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基)丙烷盐酸盐(DDPH 0.1 μmol·L^-1)对血管平滑肌细胞增殖的作用及对原癌基因及抑癌基因的影响. 结果发现: DDPH能逆转ET-1所致［³H］TdR参入量增多, 阻止血管平滑肌细胞由静止期 (G₀/G₁期)进入DNA合成期(S期)和有丝分裂期(G₂/M期), 并能逆转ET-1引起的c-fos, c-myc, c-sis原癌基因相关抗原及 mRNA表达增强, P53抑癌基因相关抗原及mRNA表达减弱. 提示DDPH能抑制血管平滑肌细胞增殖, 与癌基因调控的分子生物学机理有关.     

1-(3-(9H-Carbazol-9-yl)-1-propyl)-4-(2-methoxyphenyl)-4-piperidinol,a novel subtype selective inhibitor of the mouse type II GABA-transporter

The selectivity of new derivatives of the γ-aminobutyric acid (GABA)-uptake inhibitor, tiagabine was characterized at the four cloned mouse GABA transporters (mGAT1 through mGAT4) by measuring [³H]-GABA uptake into stably transfected baby hamster kidney cells. While tiagabine is a highly selective inhibitor of mGAT1 (K_i=0.11±0.02 μM), these derivatives exhibited low potencies at mGAT1 but differential activities at mGAT2, mGAT3 and mGAT4. In particular, 1-(3-(9H-carbazol-9-yl)-1-propyl)-4-(2-methoxyphenyl)-4-piperidinol (NNC 05-2090) was a potent inhibitor of mGAT2 (K_i=1.4±0.3 μM) showing at least 10 fold selectivity over mGAT1, mGAT3 and mGAT4. NNC 05-2090 is the first subtype selective inhibitor of mGAT2 and may represent a novel useful tool for investigating the physiological roles of GAT2 in the brain and periphery.     

Inhibition by phenothiazine derivatives of the adenylate cyclase of amphibian oocytes

The adenylate cyclase activity of membranes of Xenopus laevis oocytes and follicle cells was affected by the presence of 2-chloro-10-(3-aminopropyl)phenothiazine (CAPP) and two other antipsychotic drugs, fluphenazine and penfluridol. CAPP, at concentrations of 10 and 100 microM, had opposite effects on the activation of the oocyte adenylate cyclase by effectors that act through the G/F regulatory subunit. Under these conditions, the drug stimulated the activation by fluoride and drastically inhibited the activation by guanyl-5'-yl-imidodiphosphate [Gpp(NH)p] and by cholera toxin and GTP. The activity of the catalytic subunit measured in the presence of either Mn2+ or forskolin was not affected by 100 microM CAPP. however, concentrations of this drug above 100 microM inhibited the adenylate cyclase activated by fluoride or by forskolin and also inhibited the activity of a calmodulin-independent cyclic nucleotide phosphodiesterase present in the same oocyte membrane preparation. Oocyte adenylate cyclase has been shown previously to be inhibited by the hormone progesterone. The inhibitory effect of CAPP is additive to that measured with the hormone, indicating that these compounds act through different mechanisms. CAPP did not modify the concentration of Gpp(NH)p required to yield half-maximal activation and, although the drug inhibited more strongly at lower concentrations of Gpp(NH)p, saturating amounts of the guanine nucleotide did not reverse completely the inhibition caused by CAPP. The effects of these antipsychotic drugs on oocyte adenylate cyclase did not require the presence of free Ca2+ and were not altered by the addition of exogenous calmodulin and calcium.     

LC-MS/MS法研究1-[1-(6-甲氧基-2-萘基)乙基]-2-(4-硝基苄基)-6,7-二甲氧基-1,2,3,4-四氢异喹啉氢溴酸盐在大鼠体内的代谢产物

采用液相色谱-串联质谱法对大鼠灌胃1-［1-(6-甲氧基-2-萘基)乙基］-2-(4-硝基苄基)-6,7-二甲氧基-1,2,3,4-四氢异喹啉氢溴酸盐(编号P91024)后粪便、尿液、胆汁和血浆中的主要代谢产物进行研究。通过比较给药样品和空白样品的全扫描总离子流色谱和选择离子扫描色谱图差别寻找I相代谢产物；根据其一级和二级质谱图，确定I相代谢产物的分子结构。完全提取I相代谢产物后的样品溶液，再用葡糖醛酸酶酶解，得II相结合物的苷元部分，采用与I相代谢产物鉴定同样方法寻找和鉴定II相代谢产物苷元的结构，进而确证II相代谢产物的分子结构。从大鼠粪便中鉴定出P91024的2个I相代谢物，从胆汁中鉴定出1个I相和5个II相代谢产物，从尿液中鉴定出1个I相和3个II相代谢产物，从血浆中鉴定出4个I相和1个II相代谢产物；并分别分析推测出它们的结构。P91024在大鼠体内被代谢转化为多种产物，利用LC-MS/MS可以快速寻找和鉴定。     

1-(4-羟基苯基)-2-[1-甲基-3-(4-羟基苯基)丙氨基]乙酮盐酸盐对离体蛙心的影响

目的　研究 1- (4 -羟基苯基 ) - 2 - [1-甲基 - 3- (4 -羟基苯基 )丙氨基 ]乙酮盐酸盐对 β -受体的作用。 方法　用斯氏法制备青蛙离体心脏标本 ,用BL - 4 10生物机能实验仪记录心脏收缩活动。结果　β -受体激动剂异丙肾上腺素对离体蛙心有非常明显的兴奋作用 ,10ng·ml-1浓度时可增加离体蛙心脏收缩张力 199.2 9%± 6 9.6 9% (n =8) ;1- (4 -羟基苯基 ) -2 - [1-甲基 - 3- (4 -羟基苯基 )丙氨基 ]乙酮盐酸盐饱和上清药液 2 0 %～ 10 0 % ,对离体蛙心脏亦有明显兴奋作用 ,可分别增加离体蛙心脏收缩张力 81.4 3%± 34.4 4 %、6 0 .5 3%± 2 0 .18%、74 .5 3%± 32 .75 %、74 .34%± 39.6 9%、6 0 .91%± 2 7.73% (n =8) ,但未见明显的剂量效应关系。结论　 1- (4 -羟基苯基 ) - 2 - [1-甲基 - 3- (4 -羟基苯基 )丙氨基 ]乙酮盐酸盐对 β -受体具有激动作用。     

1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基)丙烷盐酸盐对大鼠心脏α_1受体的影响

DDPH 3 mg/kg对毁脊髓大鼠有拮抗甲氧胺升高左心室压力及室内压最大变化速率(±dP/dt_(max))、左室舒张末期压、血压和心率的作用;在大鼠离体工作心脏上,有普萘洛尔存在时,DDPH 1～10μmol/L有阻断苯福林升高左心室压力及dP/dt_(max)、主动脉流量和心率的作用;DDPH60μmol/L灌流大鼠在体心肺,有取消甲氧明提高左心室压力和心输出量的作用。DDPH尚可显著减慢大鼠工作心脏和在体心肺装置的心率。上述结果提示DDPH对血管平滑肌及心肌的α_1受体有阻断作用。     

The effect of alkylating agents and other drugs on the accumulation of melphalan by murine L1210 leukaemia cells in vitro

The effect of cytotoxic and other drugs on the accumulation of melphalan by L1210 murine leukaemia cells was studied. We have confirmed that uptake is an active process competitively inhibited by l-leucine. In 36 experiments in amino acid-free medium the mean concentration of melphalan taken up was 225 pmoles/10⁶ cells. High pressure liquid Chromatographie analysis showed that the majority of the drug is present as free native melphalan. 1, 3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) was the only drug that stimulated accumulation, but without significant effect on influx or efflux rates. Busulphan, chlorambucil, cyclophosphamide, interferon, methotrexate and prednisolone had no effect on accumulation after 30 min melphalan transport. Adriamycin, CCNU, methyl CCNU, mustine and vincristine all impaired melphalan accumulation as did the non-cytotoxic drugs aminophylline, chlorpromazine and ouabain. Adriamycin, aminophylline, chloropromazine, indomethacin and ouabain all reduced melphalan influx.     

In vitro reactivation of sarin-inhibited human acetylcholinesterase (AChE) by bis-pyridinium oximes connected by xylene linkers

A series of bis-pyridinium oximes connected by xylene linkers were synthesized and their in vitro reactivation potential was evaluated against human acetylcholinesterase (hAChE) inhibited by nerve agent sarin and the data were compared with 2-PAM and obidoxime. Among the synthesized compounds, N,N′-p-xylene-bis-[(2,2′-hydroxyiminomethyl)pyridinium] dibromide (3c) was found to be the most potent reactivator for hAChE inhibited by sarin. The oxime 3c exhibited 45% regeneration of inhibited hAChE, in comparison to 34% and 24% regeneration by 2-PAM and obidoxime, respectively, at a concentration of 10⁻³ M within 10 min. The higher reactivation efficacies of these oximes were attributed to their acid dissociation constants (pKa). The pKa values of all the oximes were determined spectrophotometrically and correlated with their observed reactivation potential. This method involving the in vitro reactivation of inhibited hAChE may be useful for the screening of new oximes as reactivators.     

1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙氨基)丙烷盐酸盐对大鼠及肝硬化模型犬门静脉血液动力学的影响

本文观察了DDPH对正常大鼠及肝硬化模型犬门静脉血液动力学的影响,发现DDPH能阻断α_1受体激功剂脱羟肾上腺素(Phen)对大鼠门静脉血管床的收缩作用,DDPH能明显降低肝硬化犬的门静脉血管阻力及门静脉压力,结果证明肝脏门静脉血管床以α_1受体调节为主,DDPH通过阻断门静脉血管床的α_1,受体,而发挥其降低犬硬化肝脏的门静脉血管阻力及门静脉压力的作用。     

Studies of the antagonist actions of (RS)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl]propionic acid (ATPO) on non-NMDA receptors in cultured rat neurones

1. Whole-cell patch-clamp recordings from single cultured cortical neurones have been used to study the action of (RS)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl]propionic acid (ATPO), which has previously been proposed to be a potent selective antagonist of 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptors.
2. ATPO competitively reduced peak responses evoked by semi-rapid applications of AMPA (K_i=16 μM) but had variable effects on plateau responses, which were on average unchanged. Following blockade of AMPA receptor desensitization by cyclothiazide (CTZ, 100 μM), the plateau responses were reduced by ATPO to a similar extent as the peak responses, indicating that ATPO reduces desensitization of AMPA receptors.
3. Semi-rapid application of kainic acid (KA) and the KA receptor-selective agonist, (2S,4R)-4-methylglutamic acid (MeGlu) evoked non-desensitizing responses which were competitively antagonized by ATPO (K_i values: 27 and 23 μM, respectively).
4. Responses to MeGlu were unaffected by CTZ (100 μM), but potentiated 3 fold following blockade of KA receptor desensitization by concanavalin A (Con A, 300 μg ml⁻¹). Responses of spinal cord neurones to MeGlu were blocked by ATPO to a similar extent before and after blockade of KA receptor desensitization by Con A.
5. Although selectively potentiated by Con A, plateau responses to MeGlu were reduced by 69.6% by the AMPA selective antagonist, GYKI 53655 (10 μM). The remaining component was further reduced by ATPO with a K_i of 36 μM, which was not significantly different from that in the absence of GYKI 53655, but was greater than that on responses to AMPA.
6. It is concluded that ATPO is a moderate-potency competitive inhibitor of naturally expressed non-NMDA receptors.

     

1-(2,6-二甲基苯氧基)-2-(3,4-二甲氧基苯乙胺基)丙烷盐酸盐对麻醉猫、大鼠心肌缺血再灌注所致心律失常的作用

DDPH是具有α肾上腺素受体阻断作用和较弱抗钙作用的新化合物。本实验研究了DDPH对麻醉猫、大鼠心肌缺血再灌注所致心律失常的作用和对猫血压的影响。结果表明,DDPH iv 0.5～3 mg/kg可降低麻醉猫血压,减少麻醉猫冠状动脉左前降支结扎时心肌缺血产生的VEB,减少麻醉猫和大鼠再灌注所致VEB和VT,VF的持续时间,降低VT,VF的发生率。对动物再灌注时由VF引起的死亡率也有降低的趋势。与哌唑嗪比较,两者具有相似的抗麻醉猫和大鼠心肌缺血再灌注所致心律失常的作用。     

TMB-8抑制神经递质引起的单个脑细胞内游离钙的升高(英文)

目的:研究TMB-8对神经递质引起的单个脑细胞内游离钙升高的作用。方法:应用AR-CM-MIC阳离子测定系统测定游离大鼠单个脑细胞内钙离子浓度。结果:当细胞外液Ca~(2 )浓度为1.3mmol·L~(-1)时,TMB-8 30μmol·L~(-1)能降低谷氨酸,组织胺,5-羟色胺引起的脑[Ca~(2 )]_i浓度的升高。而当细胞外液无钙时,TMB-8能降低细胞内静息[Ca~(2 )]_i;TMB-8 10μmol·L~(-1)则几乎完全抑制了组织胺和5-羟色胺引起的脑[Ca~(2 )]_i升高作用。结论:TMB-8能降低谷氨酸,组织胺,5-羟色胺引起的脑[Ca~(2 )]_i升高。     

Inhibition of leptin release by atrial natriuretic peptide (ANP) in human adipocytes

The addition of atrial natriuretic peptide (ANP) to isolated human adipocytes in primary culture from very obese individuals resulted in an inhibition of leptin release after a 24- or 48-hr incubation. There was also an inhibition of leptin release by isoproterenol (ISO) that was partially reversed by insulin, whereas the inhibition due to ANP was unaffected. Similar results were seen with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide (H-89), which is a cell-permeable inhibitor of protein kinase A. H-89 markedly reduced the effects of ISO on both lipolysis and leptin release without affecting the stimulation of lipolysis or the inhibition of leptin release due to ANP. Inhibition of endogenous nitric oxide formation using N(omega)-nitro-L-arginine resulted in a 20% increase in leptin release over 48 hr, which suggests that the nitric oxide/cyclic GMP pathway might play a small role in the regulation of endogenous leptin release. Similarly, the addition of the nitric oxide donor (Z)-1-[2-aminoethyl)-N-(2-aminoethyl)diazen-1-ium-1,2-diolate (DETA NONOate) at 0.1 or 1 microM to explants of human adipose tissue enhanced lipolysis by 29%. Our data demonstrate that the lipolytic effect of ANP is probably secondary to stimulation of cyclic GMP accumulation in human adipocytes, and this is accompanied by an inhibition of leptin release.