山莨菪碱和蝙蝠葛碱对白三烯和PAF诱导的牛脑前动脉平滑肌细胞DNA合成的影响(英文)

白三烯和血小板活化因子在低于nmol浓度时就能刺激培养的牛脑前动脉平滑肌细胞的DNA合成,在10~(-7)mol/L时达最大刺激。LTB_4,LTD_4和PAF在10~(-7)mol/L时对上述细胞DNA合成的刺激率分别为32％,29％和77％。山莨菪碱和蝙蝠葛碱在10~(-7)～10~(-4)mol/L范围内呈剂量依赖性地抑制白三烯和血小板活化因子的上述作用。     

蝙蝠葛碱和粉防己碱对[3H]WEB 2086与体外牛脑前动脉平滑肌细胞结合的影响(英文)

用标记的血小板活化因子拮抗剂[³H]WEB 2086,在培养的牛脑前动脉平滑肌细胞上鉴定了血小板活化因子受体。结果表明在25℃时该细胞上存在两种与配基具有不同亲和力的受体结合位点,其中K_d-1=22.8±5.0 nmol·L^-1,K_d-2=186+20.5 nmol·L^-1;B_max-1=2.1±0.3 pmol/10⁴细胞,B_max-2=12.1±1-5 pmol/10⁶细胞。蝙蝠葛碱和粉防己碱均能抑制[³H]WEB2086与上述细胞的结合。     

示波极谱法测定片剂和尿液中别嘌醇的含量

用二阶导数示波极谱法研究了别嘌醇的测定方法。在pH5.5 HAc-NaAc缓冲溶液和0.50 mol/L H₂SO₄溶液中,浓度与波高分别在3×10^-7～1×10^-4mol/L和5×10^-7～1×10^-4mol/L内呈现良好的线性关系,检测下限分别可达8×10^-8mol/L(0.011 ppm)和3×10^-7mol/L(0.041ppm)。测定了片剂和尿液中别嘌醇的含量。初步探讨了电极反应的性质。     

山莨菪碱对乙酰胆碱和去甲肾上腺素引起的兔虹膜释放前列腺素的影响

本文研究了654-2对Ach及NE引起的兔虹膜释放PGE₂及6-keto-PGF_1α作用的影响。Ach及NE使虹膜释放PGs增加,654-2对Ach释放PGs的作用呈剂量依赖性抑制,当654-2浓度为3×10^-5mol/L时,Ach(5x10^-5mol/L)引起的PGE₂及6-keto-PGF_1α的释放量分别降低31%及30%。654-2浓度高于6x10^-5mol/L时显著抑制NE(5x10^-5mol/L)释放虹膜PGs的作用,当654-2浓度为3x10^-4mol/L时,使NE增加虹膜释放PGE:及6-keto-PGF_1α的量分别从62%及34%降至7.5%及4%(p<0.01)。654-2抑制PGs释放对其抗感染性休克等作用可能是有利的。     

粉防己碱,小檗胺等四氢异喹啉类生物碱对大鼠脑内M-胆碱受体的作用

用放射受体结合方法,研究了36种四氢异喹啉类生物碱及其半合成衍生物对大鼠脑内M-胆碱受体的结合特性。实验发现,粉防己碱对M-胆碱受体的亲和力最高,其K_i值为7.3×10^-8mol/L。小檗胺、四氢黄连碱和半合成原小檗碱衍生物B₁亦具有较高亲和力,K_i值分别为1.9×10^-7,6.8×10^-7和8.1×10^-7mol/L。四氢小檗碱半合成原小檗碱衍生物B₂,B₃,B₄,B₅,B₆和半合成小檗胺衍生物E₁及半合成蝙蝠葛碱衍生物D₁对M-胆碱受体的亲和力为中等强度,K_i值在1～2×10^-6mol/L之间。实验结果提示,某些四氢异喹啉类生物碱的药理作用可能与M-胆碱受体有关。     

抗痫灵的电化学行为及吸附伏安法研究

抗痫灵在0.20 mol/L H₂SO₄底液、富集电位-0.70 V(vs Ag/AgCl)、扫速100 mV/s等条件下,用吸附伏安法得一灵敏的还原峰,峰电位-0.94 V,峰电流与抗痫灵浓度在3.0×10^-9～1.0×10^-8mol/L(富集时间t_ac=120 s),1.0×10^-8～7.0×10^-8mol/L(t_ac=90 s),7.0×10^-8～7.0×10^-7mol/L(t_ac=60 s),7.0×10^-7～3.0×10^-6mol/L(t_ac=45 s)范围内成线性关系,检测限可达1.0×10^-9mol/L,并用于片剂及病人尿样的测定,得到满意的结果。以多种电化学手段研究抗痫灵的电化学行为及反应机理。实验表明属不可逆吸附波。测得扩散系数D为7.7×10^-6cm²/s,电极反应速率常数k₁为1.5×10^-3cm/s,电极反应电子数n为2,电子转移系数α=0.52。抗痫灵的还原基团为分子中碳碳双键。     

眼睛蛇毒心脏毒素对大鼠心肌细胞收缩及细胞内钙离子的作用

目的研究眼睛蛇毒心脏毒素(Cardiotoxin,CTX)对心肌细胞的形态、收缩幅度和细胞内钙离子([Ca²⁺]_i)的作用。方法应用荧光计量法(以Fura-2/AM为荧光染料)及光学成像系统来测定单个心肌细胞[Ca²⁺]_i和收缩幅度。结果0.001～1μmol/L的CTX使心肌细胞由杆状变成圆形,药物的作用从第1分钟时开始,到第20分钟时趋于稳定。在电刺激存在的情况下,1μmol/L的CTX最初导致电诱导的[Ca²⁺]_i和收缩幅度瞬间增加,接下来[Ca²⁺]_i时程延长,最终细胞对电刺激不敏感、突然收缩、[Ca²⁺]_i持续增高。在缺乏电刺激的情况下,1μmol/L的CTX可诱导Ca²⁺震荡波、持续性[Ca²⁺]_i增高,这种作用与40mmol/L的KC l和10mmol/L咖啡因所引起的[Ca²⁺]_i瞬间增加不同。结论CTX作用初期使[Ca²⁺]_i增高,使细胞[Ca²⁺]_i超载,同时伴随细胞形状的改变。     

胆固醇的吸附氧化及差示脉冲伏安测定

胆固醇能在开路下吸附在悬汞电极的表面,并在电位扫描过程中发生氧化。在0.1 mol/LK₂HPO₄—KH₂PO₄缓冲溶液(pH 7.8)中,差示脉冲溶出峰电位在-0.08V,溶出电流与胆固醇浓度在10^-7～10^-6mol/L范围内呈线性关系。经5min富集,检测下限达8×10^-8mol/L。本文对胆固醇在电极上的吸附、氧化机理,测定条件和干扰情况进行了探讨,并提出了直接测定血清中游离胆固醇的方法。     

赛庚啶对离体犬心肌肌质网Ca2+,Mg2+—ATP酶活性和45Ca2+摄取功能的影响

当赛庚啶浓度在8×10^-6mol/L～2×10^-4mol/L之间时,该药对正常犬心肌肌质网Ca²⁺,Mg²⁺—ATP酶活性几乎没有影响,仅在10^-3mol/L时对该酶活性才有一定的抑制作用(抑制率为39.85%,P<0.01)。正常犬心肌肌质网的⁴⁵Ca²⁺摄取过程有明显的时间依赖性,至第30 min,其⁴⁵Ca²⁺摄取量可达312.79±22.25 nmol/mg protein.赛庚啶对心肌肌质网的~(45)Ca²⁺摄取有一定的抑制作用,其IC₅₀为1.94×10^-4mol/L。     

四氢异喹啉类生物碱对大鼠脑内α肾上腺素受体的作用

应用放射受体结合法研究了近30种四氢异喹啉类(TIQs)生物碱对大鼠脑内α肾上腺素受体的作用。其中l-CBN,l-THC和l-STP对α₁受体亲和力最高,K_i值为～2.0×10^-7mol/L。其次是DHS,XLP和l-DCT,K_i值分别为4.7×10^-7,6.5×10^-7和7.6×10^-7mol/L。DHS对α₂受体亲和力最高(K_i=1.25×10^-6mol/L),l-REM次之。对α受体亚型亲和力选择比K_i(alpha-2)/Ki(alpha-1)最高的是l-STP(357) 和XLP(154),它们对α₂受体几无亲和力(K_i>10^-4mnl/L)。提示l-STP和XLP对α₁受体有较高的选择性。l-SPD和l-THP对α₁和α₂受体亲和力相近,均为中等强度。THJ,DRC及l-TTD等6种TIQs对α₁和α₂受体均无亲和力(K_i>10^-4mnl/L)。     

Leukotriene formation by human polymorphonuclear leukocytes from endogenous arachidonate. Physiological triggers and modulation by prostanoids

Human polymorphonuclear leukocytes (PMN) were isolated from freshly drawn venous blood by Dextran sedimentation and discontinuous Percoll gradient centrifugation. The effects of several putative triggers of the leukotriene formation such as C5a, PAF, FMLP, C3a, PMA, LTC4, LTD4, LTB4 or arachidonate were studied by RP-HPLC analysis. 280 nM C5a, 100 nM FMLP, 1 microM PAF or 20 microM arachidonate induced a marginal formation of 1.5-18 ng of LTB4 plus LTB4 metabolites/2 x 10(7) PMN. 560 nM C3a, 100 nM PMA, 1 microM LTC4, 1 microM LTD4 and 1 microM LTB4 each failed to induce any formation of 5-lipoxygenase products. Pretreatment of the cells with 40 microM ethylmercurithiosalicylate (merthiolate) enhanced the leukotriene formation by 100 nM FMLP about 40-fold, by 280 nM C3a about 120-fold and by 1 microM PAF about 14-fold. Merthiolate itself induced no leukotriene formation from human PMN and reduced the leukotriene formation by 20 microM arachidonate. The FMLP/merthiolate-induced activation of the PMN was concentration-dependent in respect to both FMLP and merthiolate. 1 microM LTC4, 1 microM LTD4 or 1 microM LTB4 also failed to trigger any LTB4 formation of merthiolate-treated PMN. 560 nM C3a or 100 nM PMA in combination with 40 microM merthiolate induced a slight formation of 28 ng and 10 ng of LTB4 plus LTB4 metabolites, respectively. The FMLP/merthiolate-induced leukotriene formation was modulated by prostanoids. PGE2, PGE1, PGD2 and 6-keto-PGE1 each evoked a concentration-dependent inhibition of the leukotriene formation with IC50 values of 0.07 microM, 0.18 microM, 0.27 microM and 6 microM respectively. In addition, significant inhibitory effects by PGI2, Iloprost (a carbacyclin analogue of prostacyclin), PGF2a or 6-keto-PGF1a were achieved; the corresponding IC50 values, however, amounted to 19-59 microM. Thus these compounds were about 500-fold less potent in comparison with PGE2 in inhibiting LTB4 formation by human PMN.     

Anti-platelet activating factor, anti-leukotriene D4 and some other antiallergic activities of mequitazine.

The bronchoconstrictions of guinea pigs elicited in vivo by leukotriene D4 (LTD4) and platelet activating factor (PAF) were inhibited by pretreatment with mequitazine (CAS 29216-28-2) (p.o.) in a dose-dependent manner at doses of 5-20 mg/kg. Mequitazine (0.5-50 nmol/l) also inhibited LTD4- and PAF- induced contractions of guinea pig tracheal chain. These results suggest that mequitazine possesses antagonistic activity for LTs and PAF; the effects of mequitazine against these two agonists were much more potent than those of ketotifen. The histamine release induced by either of compound 48/80, concanavalin A or A23187 was inhibited by mequitazine at concentrations ranging from 1 to 20 mumols/l. In the inhibition process, mequitazine may act not only to inhibit the Ca2+ release from intracellular Ca store of mast cells but also to stabilize the lipid bilayer of the cell membrane as shown in the order parameter and hypotonic hemolysis. From the present study, it was assumed that mequitazine may exert antiallergic activity by antagonizing LTs and PAF as well as by inhibiting histamine release from mast cells.     

Gastrointestinal damage induced by platelet-activating factor: role of leukotrienes

The role of leukotriene synthesis in the gastrointestinal damage induced by platelet-activating factor (PAF) was examined in the rat. The effects of a 20-min infusion of PAF (100 ng/kg per min) on leukotriene B4 (LTB4) and leukotriene C4 (LTC4) synthesis were examined in samples of the stomach, duodenum, jejunum, ileum and colon. Administration of PAF resulted in marked hemoconcentration and extensive hemorrhagic damage which was only observed in the corpus region of the stomach and in the small intestine. However, LTB4 synthesis was increased significantly in all regions studied, while LTC4 synthesis was increased significantly only in the duodenum. Pretreatment of the rats with dexamethasone significantly reduced the PAF-induced increase in LTB4 synthesis in all tissues studied. However, a reduction of PAF-induced damage following dexamethasone treatment was observed in the small intestine, but not the stomach. To further investigate the role of leukotrienes as mediators of PAF-induced gastrointestinal damage, the effects of a 10-min infusion of PAF (100 ng/kg per min i.v.) were compared to those of similar infusions of LTB4, LTC4 or leukotriene D4 (LTD4) (0.3-3 micrograms/kg per min). None of the doses of leukotrienes tested produced hemoconcentration or gastrointestinal damage comparable to that observed with the much lower dose of PAF, with the single exception of significant hemoconcentration observed with the highest dose of LTC4. The results of this study therefore suggest that leukotrienes are unlikely to play a major role as mediators of PAF-induced gastrointestinal damage in the rat.     

Evidence for two leukotriene receptor types in the guinea-pig isolated ileum

Leukotriene (LT) receptors in the guinea-pig ileum were characterized using LTB4, LTC4, LTD4 and LTE4 and the LT antagonists FPL 55712, ICI 198615 and (+/-)SKF 104353. LTB4 was inactive but the other LTs induced concentration-related contractions. LTC4 responses differed to those induced by LTD4 or LTE4. Inhibitors of LT metabolism had no significant effects on any LT responses. LTD4 contractions were inhibited by all three antagonists but a resistant response was apparent at concentrations of ICI 198615 greater than 10(-8) M. All three antagonists were weak/inactive against LTC4. LTE4 was a partial agonist which antagonized LTD4 responses but had little or no activity against LTC4 or histamine. These results suggest that two distinct LT receptor types exist on guinea-pig ileum. One type is predominantly activated by LTD4 and is antagonized by three structurally distinct LT antagonists and the partial agonist LTE4. The second type is predominantly activated by LTC4 and is insensitive to the LT antagonists.     

Differential effects of fexofenadine on arachidonic acid metabolism in cultured human monocytes

The relief of nasal congestion with the antihistamine fexofenadine in seasonal allergic rhinitis is thought to be due to its additional anti-inflammatory properties. The objective of this study was to evaluate the in vitro effects of fexofenadine on stimulated arachidonic acid metabolism. Human monocytes, isolated from blood and donated by 5 healthy volunteers, were either incubated for 20 h with 10 microg/ml lipopolysaccharide, with and without fexofenadine (10(-8)-10(-3) mol/l, n = 8-19), or were incubated for 20 h, with and without fexofenadine, and then stimulated with 0.5 mg/ml zymosan for 2 h. Leukotriene B4 (LTB4), LTC4, LTD4 and LTE4, prostaglandin E2 (PGE2) and F2alpha (PGF2alpha) production was determined by enzyme immunoassay. Zymosan-stimulated production of LTC4, LTD4 and LTE4 was significantly inhibited by clinically relevant concentrations of fexofenadine HCl: 10(-7) mol/l (22% inhibition vs. control, p = 0.008) and 10(-6) mol/l (24% inhibition vs. control, p = 0.020). Higher concentrations of fexofenadine (10(-4) and 10(-3) mol/l) inhibited LTB(4) generation. Lipopolysaccharide-stimulated production of PGE2 was significantly inhibited by fexofenadine HCl 10(-6) mol/l (26% inhibition, p = 0.035) and 10(-5) mol/l (40% inhibition, p = 0.001). Higher concentrations of fexofenadine HCl (10(-4) and 10(-3) mol/l) significantly inhibited PGF2alpha production by 50% (p = 0.026) and 63% (p = 0.001), respectively. Fexofenadine, at both clinically relevant and higher concentrations, inhibits LTC4, LTD4, LTE4 and PGE2 in cultured human monocytes. These additional anti-inflammatory properties may underlie the relief of nasal congestion observed in clinical studies.     

Granulocyte chemotaxis in the canine trachea: inhibition by lipid mediator antagonists and systemic inhibitors.

Inflammation of the airways contributes to the multicomponent disease known as asthma. The primary cells that infiltrate the airways in response to antigen exposure are PMNs and eosinophils, cells that can release cellular components, and damage the airways. We adapted a double-balloon endotracheal tube to study the cellular response to three de novo synthesized lipid mediators (LTB4, PAF-acether and 15 HETE) found in respiratory fluids following antigen exposure. In random repeat challenges in groups of 7 dogs using mongrel dogs at 240 min following exposure to 10(-6) M agonists, the PMN content of the perfused fluid was 870 +/- 240, 1632 +/- 883, 515 +/- 395, and 1575 +/- 214 cells/ml/5 high power fields for vehicle, LTB4, PAF, and 15 HETE respectively. Eosinophils that infiltrated the lumen at 240 min were 162 +/- 23, 608 +/- 287, 502 +/- 23, 115 +/- 14 cells/ml/5 HPF for vehicle, LTB4, PAF, and 15 HETE respectively. Thus LTB4 and PAF-acether significantly (p less than 0.05) increased eosinophils, and LTB4 and 15 HETE increased PMNs (p less than 0.05). After determining the agonist response for the 3 agonists we included 2 specific antagonists in the perfusate. The LTB4 antagonist U-75,302 10(-5) M, and the PAF antagonist L 652,731 10(-5) M in chambers containing LTB4 and PAF-acether respectively blocked significantly the influx of PMNs and eosinophils compared to vehicle (p less than 0.01). Methylprednisolone 5 mg/kg i.m.--18 hrs blocked eosinophilia to PAF and LTB4. Oral U-78,517F a Trolox amine lazaroid, active as an inhibitor of lipid peroxidation, 30 mg/kg--18 hrs significantly blocked eosinophilia to PAF-acether and LTB4 directed chemotaxis compared to vehicle (p less than 0.05) but not 15 HETE. Specificity was shown for each antagonist since the PAF and LTB4 antagonists did not block the opposite agonist. Use of this novel in vivo chemotaxis model allows the additional advantage of studying chemotaxis in living tissue.     

Inhibition of neutrophil and eosinophil induced chemotaxis by nedocromil sodium and sodium cromoglycate.

1. Neutrophils and eosinophils infiltrate the airways in association with the allergen-induced late phase asthmatic reaction. Mobilization of these cells takes place via lipid-like and protein-like chemotactic factors. In this study platelet-activating factor (PAF), leukotriene B4 (LTB4), zymosan-activated serum (ZAS) and N-formyl-methionyl-leucyl-phenylalanine (FMLP) were used as illustrative examples of both groups. Chemotaxis was studied in human neutrophils and eosinophils. The inhibitory effects of nedocromil sodium and sodium cromoglycate were evaluated. 2. All chemotactic factors tested attracted neutrophils with the following rank order of activity: ZAS greater than PAF identical to FMLP identical to LTB4. Eosinophils were only mobilized by PAF, LTB4 and ZAS with the following rank order of activity: ZAS greater than PAF greater than LTB4. 3. Nedocromil sodium and sodium cromoglycate were equally active as the PAF antagonist BN 52021 in inhibiting the PAF-induced chemotaxis of neutrophils (IC50 approximately 10(-8) M). Both drugs were also equally active in inhibiting the chemotaxis of neutrophils induced by ZAS (IC50 approximately 10(-7)-10(-6) M), FMLP (IC50 approximately 10(-7) M) and LTB4 (IC50 approximately 10(-6) M). 4. Nedocromil sodium significantly inhibited the chemotaxis of eosinophils induced by PAF (IC50 approximately 10(-6) M) and LTB4 (IC50 approximately 10(-7) M). The inhibitory potency of BN 52021 was similar to that of nedocromil sodium on the PAF-induced chemotaxis of eosinophils. Sodium cromoglycate was incapable of eliciting significant inhibition of these chemotactic responses. However, sodium cromoglycate significantly inhibited the chemotaxis of eosinophils induced by ZAS (IC50 approximately 10(-7) M), whereas nedocromil sodium was ineffective.