The effects of changes to action potential duration on the calcium content of the sarcoplasmic reticulum in isolated guinea-pig ventricular myocytes

. We have estimated sarcoplasmic reticulum calcium content using rapid application of caffeine on voltage clamped, isolated guinea-pig ventricular myocytes. Caffeine induces the release of calcium from the sarcoplasmic reticulum and this calcium is extruded from the cells by the sarcolemmal Na/Ca exchange. Integrating the inward Na/Ca exchange current thus allows estimations of sarcoplasmic reticulum calcium content. Ventricular myocytes were stimulated to reach new steady-states by action potential voltage clamps of varying duration. Once contractile steady-state had been reached caffeine was rapidly applied in place of the next action potential and sarcoplasmic reticulum calcium content measured. Prolonging the action potential duration increased sarcoplasmic reticulum calcium content and vice-versa. This calcium loading may underlie the positive inotropic effect of increased action potential duration. Received: 11 July 1996 / Received after revision: 15 October 1996 / Accepted: 26 November 1996     

重视药物利用评价研究,开展药物利用评价活动

药物利用评价是当前医院合理用药的深入发展的重要体现,也是临床药学的重要工作之一。本文论述了药物利用评价的目的、意义、方法和进展,以及药物利用评价在医院药房中的应用,以期引起有关人员的重视。     

RELAXATION OF MESENTERIC ARTERY OF STROKE PRONE SPONTANEOUSLY HYPERTENSIVE RATS BY CALCIUM REMOVAL

1. The time courses of the relaxation, induced by removal of extracellular Ca2+, of K-depolarized mesenteric artery preparations from stroke prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) were compared. 2. The time course of the decline in extracellular Ca2+ was estimated from the time course of the relaxation and the concentration-response curve of K(+)-depolarized preparations to Ca2+. The time course of the decline in the intracellular free Ca2+ concentration was also estimated from the reported relation between Ca2+ concentration and the contraction of skinned vascular smooth muscle. 3. The time course of relaxation was exponential, the curve being made up of three components. The time course was slower in preparations from SHRSP, especially the first component of the relaxation curve. 4. The time courses of the decline in the intracellular and extracellular Ca2+ concentrations were also exponential, being made up of three components and were also slower in the preparation made from SHRSP. 5. The wall and muscle layer of the mesenteric arteries used in the present experiments were significantly thicker in the SHRSP preparations. 6. Calculation of the half relaxation time, based on the diffusion of Ca2+ across the blood vessel wall, suggested that the slower relaxation in preparations from SHRSP is due largely to the thicker muscle layer, although differences in Ca2+ sequestration by the smooth muscle cells may also be involved.     

神经生长因子对小鼠突触体内Ca^2＋水平的调节作用

观察了多次海马内微注射ＮＧＦ对小鼠突触体内游离钙水平的影响，并在离体情况下观察ＮＧＦ对ＥＧＴＡ和ＣａＣｌ２分别造成突触体内低钙和高钙状态的调节作用。结果如下：（１）在体实验表明，一定剂量的ＮＧＦ可显著降低老年小鼠海马突触体内游离钙水平（Ｐ＜００５）；（２）离体实验表明，当突触体游离钙水平降低时，适当剂量的ＮＧＦ具有升高游离钙水平的作用；而突触体内游离钙水平升高时，则ＮＧＦ有降低游离钙水平的作用。提示ＮＧＦ对游离钙水平的双向调节作用可能是ＮＧＦ改善老年性记忆衰退的作用机制。     

镉对肾脏的毒作用

雄性Ｗｉｓｔａｒ大鼠２４只，随机等分为４组，皮下注射不同剂量的ＣｄＭＴ。结果显示镉接触组尿钙和尿蛋白都高于对照组；肾皮质钠泵和钙泵活性低于对照组，体外试验也显示镉能抑制钙泵活性，ＧＳＨ和半胱氨酸对这种抑制有保护作用；肾皮质ＧＳＨ含量低于对照组，ＭＤＡ含量则高于对照组，但肝脏的这两个指标无变化；高剂量组ｃＡＭＰ／ｃＧＭＰ的比值低于对照组。提示脂质过氧化和钙代谢障碍是镉引起肾损害的机理之一。     

重质石油中含氮化合物的形态及分布分析Ⅱ．含氦杂环化合物的定性方法

探索了色谱保留值与质谱信息相结合的定性分析方法。用ＳＥ－５４柱代替ＳＥ－５２柱，选用六个多环芳烃化合物作为标准计算保留指数，从而改善了Ｍ．Ｌ．Ｌｅｅ保留指数的应用条件和范围；用文献值转换扩充了Ｌｅｅ的含氮杂环化合物保留指数表，并利用保留时间与沸点的关系作定性佐证。应用该法鉴定了重质石油样品子组分及萘油中的４６个含氮杂环化合物及其异构体，为质谱在异构体鉴定以及缺乏标样所产生的困难提供了可信、简便的定性鉴定方法。     

Nd：YAG激光对牙本质钙／磷比值的影响

为探讨Ｎｄ：ＹＡＧ激光对牙本质矿物含量的影响，应用扫描电镜和能谱仪定点测量５０个上前牙标本的根管壁（激光照射工和正常对比区）的钙、磷含量，结果表明，照射区牙本质钙／磷（Ｃａ／Ｐ）比值高于对比区，当激光能量达１５Ｗ以上时变化更为显著，提示Ｎｄ：ＹＡＧ激光能提高牙本质的钙化程度。     

纸质病案保存期限的思考

本文作者比较了不同时期的纸质病案的使用率,讨论了旧病案的缺点,如难于保存,占用空间及实用价值不大.作者提出了改进保存病案的办法.     

黄芪对SHR心肌SERCA表达及血管平滑肌钙离子水平影响的初步探讨

目的:探讨黄芪注射液对SHR心肌SERCA的表达及血管平滑肌钙离子含量的影响.方法:将19只自发性高血压大鼠(SHR)与16只Wistar-kyoto大鼠(WKY)随机各分为空白对照组、低黄芪剂量组、中黄芪剂量组、高黄芪剂量组四组,分别每天腹腔注射0.9ml生理盐水和0.9ml、1.2ml、1.8ml的黄芪注射液共8周,再测量大鼠心肌中SERCA的表达和血管平滑肌钙离子含量.结果:SHR生理盐水组心肌SERCA在蛋白水平的表达,较WKY生理盐水组明是下降;SHR大剂量黄芪组心肌SERCA在蛋白水平的表达,较SHR生理盐水组明显升高.SHR生理盐水组血管平滑肌钙离子水平明显高于WKY组:SHR大剂量黄芪组血管平滑肌钙离子水平较SHR生理盐水组明显降低.结论:大剂量黄芪注射液能显著增加SHR心肌SERCA在蛋白水平的表达,能明显的减少SHR血管平滑肌钙离子的水平.     

磷脂酶C与生殖

磷脂酶C(PLC)是磷脂酰肌醇信号转导途径中一个关键酶。目前确认的哺乳类PLC共有PLC β、PLC γ、PLC δ、PLC ε和最近新发现的PLC ζ 5种亚型 ,12种同工酶。不同亚型的结构、调控和组织分布各有差异。PLC在调控信号转导通路中的特性使其在顶体反应、卵子激活中发挥了巨大的作用。本文综述了PLC家族 5种亚型的结构、调控机制及PLC在男性生殖领域的相关内容 ,包括PLC引起卵子发生Ca2 + 振荡、激活卵子、促进胚胎发育等 ,并进一步探讨了PLC在临床上可能的应用前景。