不同条件下吡喹酮对日本血吸虫雄虫摄入钙的影响

吡喹酮仅在较短时间内增加体外培养的日本血吸虫♂虫对~(45)Ca~(2+)的摄入量。在含30 mMMg~(2+)的HBS中,吡喹酮对♂虫摄入~(45)Ca~(2+)的量无明显影响。在4℃的HBS中,吡喹酮可使♂虫对~(45)Ca~(2+)的摄入量至少在1小时内持续增加。此外,在无Ca~(2+)的HBS中,血吸虫♂虫已摄入的~(45)Ca~(2+)的释放量较在HBS中的显著为多。     

吡喹酮对日本血吸虫雄虫的Ca2+,Mg2+,K+与Na+的含量及45Ca2+在虫体内分布的影响

日本血吸虫雄虫在4℃或37℃的HBS及无⁴⁵Ca²⁺的HBS中经吡喹酮1或30μg/ml作用0.5～2h后,未见虫的Ca²⁺,Mg²⁺含量有明显变化,但除4℃的HBS组外,余2组虫的K⁺含量明显减少,而虫的Na⁺含量的增加则不明显。在含30 mM Mg²⁺的HBS中,雄虫经吡喹酮作用1h后,虫的Mg²⁺含量明显增加。在37℃的HBS中,血吸虫雄虫经吡喹酮1μg/ml作用5～60min后,虫的皮层胞质中的⁴⁵²⁺含量的百分比较各相应对照组的明显减少,而虫体肌肉的则相反。在4℃的HBS或无⁴⁵Ca²⁺的HBS中,吡喹酮对⁴⁵²⁺在虫体内的分布无明显影响。     

吡喹酮对日本血吸虫雄虫的Ca~(2 ),Mg~(2 ),K~ 与Na~ 的含量及~(45)Ca~(2 )在虫体内分布的影响

日本血吸虫雄虫在4℃或37℃的HBS及无~(45)Ca~(2α)的HBS中经吡喹酮1或30μg/ml作用0.5～2h后,未见虫的Ca~(2 ),Mg~(2 )含量有明显变化,但除4℃的HBS组外,余2组虫的K~ 含量明显减少,而虫的Na~ 含量的增加则不明显。在含30 mM Mg~(2 )的HBS中,雄虫经吡喹酮作用1h后,虫的Mg~(2 )含量明显增加。在37℃的HBS中,血吸虫雄虫经吡喹酮1μg/ml作用5～60min后,虫的皮层胞质中的~(45)Ca~(2α)含量的百分比较各相应对照组的明显减少,而虫体肌肉的则相反。在4℃的HBS或无~(45)Ca~(2α)的HBS中,吡喹酮对~(45)Ca~(2α)在虫体内的分布无明显影响。     

日本血吸虫对3H-吡喹酮的摄入与分布

感染小鼠一次口服³H-吡喹酮100mg/kg后,其体内两性血吸虫的³H含量以给药后0.5～1小时为最高,4小时后则有明显减少。体外培养的血吸虫亦能迅速摄取³H-吡喹酮,且其摄入量随药物浓度的增加而递增。体内、体外试验的结果表明,最初进入虫体的³H-吡喹酮系脂溶性,随后在体内缓慢代谢为水溶性。放射自显影的结果说明,³H主要自表皮进入虫体,分布于肌层、间充组织、生殖系统和肠壁上皮细胞,其中以雌虫的卵黄腺为最多,而以雄虫的睾丸为最少。     

吡喹酮对日本血吸虫摄入与释放5-羟色胺的作用

用体内、体外方法观察了吡喹酮对血吸虫摄入与释放5-羟色胺的作用。根据试验结果分析,认为由于吡喹酮不增加虫体的内源性5-羟色胺含量,亦不增强其对外源性5-羟色胺的摄入,故吡喹酮对血吸虫的兴奋与挛缩作用可能并非通过5-羟色胺。感染家兔体内的合抱日本血吸虫5-羟色胺含量为1.59±0.44μg/g湿重;雌、雄虫的则分别为1.08±0.11和2.28±0.23μg/g湿重。感染小鼠体内的合抱血吸虫5-羟色胺含量为1.14±0.01μg/g湿重。血吸虫的内源性5-羟色胺相当稳定,在体外培养6小时后未见明显减少。培养液中的5-羟色胺浓度高达5×10^-4～1×10^-3M时,血吸虫对5-羟色胺始有较明显的摄入,且摄入后易于释放。     

小檗碱对培养大鼠心肌细胞胞内游离Ca2+的作用

利用Fura-2技术和AR-CM-MIC阳离子测定系统,直接观察了小檗碱对培养大鼠心肌细胞胞内[Ca²⁺]i的影响。结果显示:小檗碱可明显升高心肌细胞静息[Ca²⁺]i且具饱合性,维拉帕米和CoCl₂对其有一定的抑制作用;小檗碱与高K⁺,高Ca²⁺,去甲肾上腺素,哇巴因合用比单用上述激动剂更能明显增高[Ca²⁺]i;维拉帕米对其有抑制作用;在胞外无外Ca²⁺和无外Ca²⁺,外K⁺,外Na⁺时,小檗碱30～200μmol·L^-1仍能升高静息[Ca²⁺]i,维拉帕米只对前者有一定抑制作用。结果提示:小檗碱可能通过促胞外Ca²⁺内流和胞内Ca²⁺释放等途径有限度地增高心肌细胞内游离Ca²⁺浓度,显示强心作用。     

羟苯氨酮对心肌肌钙蛋白C与Ca2+亲和力的影响

目的:探讨羟苯氨酮(oxyphenam one , Oxy) 的钙增敏机理。方法:从牛心肌组织中提取cTn C,采用荧光探针标记法观察Oxy 对c Tn C与Ca²⁺ 亲和力的影响,并和已知的钙增敏剂 MCI-154 、磺甲唑(sulmazole , Sul) 作比较。结果: Oxy 显著增加cTn C和Ca²⁺ 的亲和力,且呈剂量与效应相关。而50 μm ol·L^-1 MCI-154 或Sul 对cTn C和Ca²⁺亲和力曲线均无显著影响。结论: Oxy 的钙增敏机理可能与直接增加cTn C与Ca²⁺ 的亲和力有关。     

兴奋毒性对海马脑片Ca2+/CaM PK Ⅱ活性的影响

用离体孵育的大鼠海马脑片模型,研究兴奋毒性与Ca²⁺/CaMPKII活性的关系。结果表明,外源性谷氨酸或NMDA均可抑制Ca²⁺/CaMPKII的活性,此活性的抑制可被MK801完全拮抗,而DNQX却无明显拮抗作用;无胞外Ca²⁺时,谷氨酸导致的酶活性抑制程度不如有胞外Ca²⁺时显著;无胞外Mg²⁺时,谷氨酸导致的酶活性抑制程度比有胞外Mg²⁺时显著。结果提示兴奋毒性对Ca²⁺/CaMPKII活性的抑制与NMDA受体介导的兴奋毒性有关。     

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。     

羟苯氨酮强心作用的生化机理研究

目的：研究羟苯氨酮(oxyphenamone, Oxy)强心作用的生化机理。方法：采用Na⁺,K⁺-ATP酶活性和cAMP-PDE活性、肌浆网Ca²⁺-ATP酶活性和cAMP含量以及心肌肌原纤维Ca²⁺,Mg²⁺-ATP酶活性等测定法,研究Oxy对它们的影响,并与milrinone和MCI-154作比较。 结果：Oxy对Na⁺,K⁺-ATP酶和PDE无抑制作用,也不影响心肌cAMP含量,但能显著增强心肌肌原纤维对Ca²⁺的敏感性,高浓度时轻度抑制心肌肌浆网Ca²⁺-ATP酶活性。结论：Oxy的强心作用方式不同于强心苷、β受体激动剂和PDE抑制剂等强心药,可能为一种新的钙增敏性强心药物。     

吡喹酮抗日本血吸虫雄虫过程中免疫血清的作用

体内或体外培养的血吸虫雄虫经一定浓度的吡喹酮作用后,移置含免疫血清的培养液中培养时,受损害的虫体体表有大量絮粒状物沉积,形成膜状包被,加重皮层的损害;在继续培养3天时,大部分或全部虫未见有明显恢复。若将虫移置含正常血清的培养液中培养时,则无此种现象,且大部虫的体表损害有不同程度的恢复。上述结果亦为扫描电镜的观察所证实。     

吡喹酮引起的日本血吸虫体表皮层的损害和宿主白细胞侵入虫体的观察

感染日本血吸虫的小鼠一次口服吡喹酮300mg/kg后0.5小时,雄虫体表皮层即有不同程度的水肿、空泡样变化和空泡破裂,继则有细絮状物或絮状团块粘附在受损的体表或抱雌沟内。给药6小时后即见有白细胞附着在受损的皮层上,12小时后则已有白细胞侵入虫体。雌虫体表皮层的损害和出现白细胞附着与侵入虫体的时间较雄虫为迟。此外,对血吸虫经吡喹酮作用后,其皮层的损害和白细胞的附着与侵入虫体的意义进行了一些讨论。     

吡喹酮对体外培养的日本血吸虫的作用

吡喹酮(Praziquantel,Embay 8440)系一种具有抗绦虫和抗血吸虫作用的广谱抗寄生虫新药。动物实验证明,该药对小鼠、家兔和犬的日本血吸虫病都有很好的疗效,且毒性低,疗程短;临床上用吡喹酮的1～2天疗法治疗日本血吸虫病,总剂量为45～90mg/kg时,治后半年的粪检虫卵转阴率达99.7％。本文报道吡喹酮对体外培养的日本血吸虫的作用。     

吡喹酮合并呋喃丙胺治疗动物血吸虫病的研究

动物实验与临床研究证明,吡喹酮对日本血吸虫的杀虫效果显著。鉴于小剂量吡喹酮有使血吸虫迅速挛缩和肝移的作用,故设想吡喹酮合并呋喃丙胺有可能获得较高的疗效。本文报道吡喹酮对感染小白鼠与兔体内血吸虫的肝移情况、合并呋喃丙胺的疗效以及合并用药的毒性。     

Effects of methoxamine and barium on 45Ca2+ fluxes in the rat vas deferens

The aim of this study was to determine whether methoxamine and barium stimulate ⁴⁵Ca²⁺ uptake or efflux in the rat vas deferens in a manner that correlates with their contractile activity, and whether ⁴⁵Ca²⁺ movements are inhibited by verapamil or nifedipine. Basal La³⁺-resistant (cellular) ⁴⁵Ca²⁺ uptake was significantly greater in the epididymal half (791 ± 27 nmol g⁻¹) than in the prostatic half (654 ± 14 nmol g⁻¹) of the rat vas deferens and was unaffected by verapamil (61 μM) or nifedipine (14 μM). Methoxamine (8 μM) was without effect on ⁴⁵Ca²⁺ uptake in either half but BaCl₂ (1 mM) increased ⁴⁵Ca²⁺ uptake by 31% in the prostatic half and by 22% in the epididymal half. The barium-induced increases in ⁴⁵Ca²⁺ uptake were markedly reduced or abolished by verapamil (2 μM) or nifedipine (0.3 μM), which at these concentrations have no effect on the rhythmic contractions but abolish the initial small phasic contraction induced by barium. The basal rate of ⁴⁵Ca²⁺ efflux from the intact vas deferens (into Ca²⁺ containing Krebs-Henseleit solution or into Ca-free Krebs-Henseleit solution ± EGTA 0.05 mM) was not affected by verapamil (61 μM) or nifedipine (14 μM). Methoxamine (8 μM) produced a marked, transient and reversible increase in ⁴⁵Ca²⁺ efflux into 2.5 mM CaCl₂ Krebs-Henseleit in 50% of the intact vasa deferentia examined which was augmented by verapamil (61 μM). BaCl₂ (1 mM) produced a small increase in ⁴⁵Ca²⁺ efflux into Ca²⁺-containing and Ca²⁺-free Krebs-Henseleit solutions from some intact vasa deferentia and this was not inhibited by nifedipine (14 μM). It is concluded that the BaCl₂-induced increase in ⁴⁵Ca²⁺ uptake is likely to be associated with the initial phase of the contractile response, rather than the secondary rhythmic contractions. Rhythmic contractions initiated by methoxamine and barium may be initiated by ‘trigger Ca’ entering through a population of calcium channels that have low affinity for calcium antagonist drugs.     

吡喹酮引起的日本血吸虫体表皮层的损害和宿主白细胞侵入虫体的观察

感染日本血吸虫的小鼠一次口服吡喹酮300mg/kg后0.5小时,雄虫体表皮层即有不同程度的水肿、空泡样变化和空泡破裂,继则有细絮状物或絮状团块粘附在受损的体表或抱雌沟内。给药6小时后即见有白细胞附着在受损的皮层上,12小时后则已有白细胞侵入虫体。雌虫体表皮层的损害和出现白细胞附着与侵入虫体的时间较雄虫为迟。此外,对血吸虫经吡喹酮作用后,其皮层的损害和白细胞的附着与侵入虫体的意义进行了一些讨论。     

Differences in alkaline earth stimulation of neurotransmitter release from isolated brain synaptosomes

Summary In the presence of 15 or 55 mM K⁺ buffer (calcium-deficient), pulses of the alkaline earths (Ca²⁺, Sr²⁺, Ba²⁺) stimulated secretion of previously accumulated [¹⁴C]GABA and [³H]norepinephrine (NE). For a 1 mM alkaline earth pulse in the presence of 15 mM K⁺, both GABA and NE release were ordered Ba²⁺>Sr²⁺>Ca²⁺. On the other hand, in 55 mM K⁺ the ordering was Ba²⁺>Sr²⁺Ca²⁺. The change in ordering resulted from an increase in Ca-dependent release at higher K⁺. In fact, Ba-dependent release was smaller in 55 mM K⁺ solution than in 15 mM K⁺ solution.D-600 (10 M), an antagonist of calcium influx, decreased both Ca- and Ba-dependent release of [¹⁴C]-GABA and [³H]NE in 15 mM K⁺ buffer. D-600 inhibited Ca-dependent release 60–70% whereas Ba-dependent release was inhibited only 30–45%.A CaCl₂ (1 mM), BaCl₂ (1 mM) or KCl (30 mM) pulse in 15 mM K⁺ buffer increased both [¹⁴C]GABA and endogenous GABA release. The Ba²⁺ pulse released more [¹⁴C] and endogenous GABA than did the Ca²⁺ pulse. The 30 mM KCl pulse released less [¹⁴C] and endogenous GABA than did either the Ba²⁺ or the Ca²⁺ pulse. However, the specific activity of the K-induced release was significantly higher than the specific activity of either Ca- or Ba-dependent GABA release.In substituting for Ca²⁺, Ba²⁺ may gain intracellular access to stimulus-secretion coupling processes via permeation at both Ca²⁺ and K⁺ ionophores.Supported by: NINCDS Grant 08597 and an NSF Predoctoral Fellowship to J. W. Haycock. C. W. Cotman is the recipient of a Research Scientist Award from the National Institute on Drug Abuse