乙酰胆碱在刺激SⅡ区影响C类纤维传入诱发的SI区电反应中的作用

电刺激猫大脑皮层体感Ⅱ区(SⅡ)对隐神经C类纤维传入引起的体感Ⅰ区(SⅠ)诱发电位(C—CEP)有抑制和易化作用。在SⅠ区局部用阿托品能部分地阻断电刺激SⅡ区对C—CEP的抑制作用,但对易化作用的影响不明显;而用六烃季铵(C_6)能阻断易化作用,但对抑制作用的影响却不明显。在SⅠ区局部应用0.01％乙酰胆碱(ACh)对C—CEP有易化作用,用0.1％ACh则有抑制作用。结果提示,ACh可能参与SⅡ区对SⅠ区C—CEP的影响,通过SⅠ区的胆碱能M受体起抑制作用,通过N受体起易化作用。     

2种新型ω-芋螺毒素的合成及作用靶点鉴定

目的:合成2个来自泡芋螺的新型ω-芋螺毒素Bu1、Bu13,测定其作用靶标,为研制新型镇痛药提供先导化合物。方法:固相合成线性肽,然后在折叠液(0.5 mol/L乙酸铵、1 mmol/L谷胱甘肽、0.1 mmol/L氧化谷胱甘肽)中于4℃折叠24～48 h,富集纯化得目标肽;利用膜片钳技术,测定其对N、P/Q及L型钙离子通道的抑制活性。结果:Bu1、Bu13对N型钙离子通道的半抑制浓度(IC50)分别为0.86、1.02μmol/L,抑制作用低于MⅦA(IC50=0.21μmol/L);10μmol/L Bu1、Bu13对P/Q型钙离子通道的抑制率分别为17.05%±1.34%、13.1%±2.69%,稍高于MⅦA(8.92%±2.12%);10μmol/L Bu1、Bu13对L型钙离子通道的抑制率分别为19.31%±6.22%、4.78%±0.77%,高于MⅦA(<5%)。结论:Bu1、Bu13选择性作用于N型钙离子通道,对P/Q、L型钙离子通道的抑制作用较低。     

中国人群中STK15基因内两种非同义SNP的连锁不平衡和单体型分析

STK15基因编码一种丝氨酸苏氨酸蛋白激酶,哺乳动物细胞中其过量表达将导致中心体扩增、染色体不稳定和细胞癌变。STK15基因外显子3中有3种非同义单核苷酸多态(SNP),即：91A→T(131F)、169G→A(V571)和311C→T(S104L)。新近研究发现,91A→T与人类肿瘤遗传易感性相关。应用PCR-RFLP技术确定了91A→T(131F)和169G→A(V571)两种SNP在中国人群中的基因型和单体型。采用巢式PCR方法扩增了193例正常个体的DNA样品,通过错配正向巢式内引物引入EcoRⅠ酶切位点。巢式PCR扩增产物用限制性内切酶EcoRⅠ和ACCⅡ双酶切消化,其中EcoRⅠ能酶切91A,AccⅡ能切开169G,用聚丙烯酰胺凝胶电泳银染法鉴定双酶切结果,发现了4种可能的单体型中的3种,其单体型频率分别为：p(91A-169G)=68．65％,p(91T-169A)=10．88％,p(91T-169G)=20．47％,p(91A-169A)=0％;它们组成的6种基因型及频率分别为：91A-169G／91A-169G(46．11％),91A-169G／91T-169A(14．51％),91A-169G／91T-169G(30．57％)．91T-169G／91T-169G(3．11％),91T-169G／91T-169A(4．15％),91T-169A／91T-169A(1．55％)。等位基因及单体型数据分析结果表明,91A→T(131F)和169G→A(V571)之间存在连锁不平衡。     

阴离子通道参与了harpin_(Pss)诱导的烟草细胞早期防卫反应的信号传导

无论在harpin_(Pss)之前、同时、还是之后向烟草植株或悬浮培养系加阴离子通道的抑制剂DIDS(4,4’-diisothiocyanatostilbene-2,2’-disulfonic acid)或AgC(anthracene-9-carboxylic acid),都可以抑制harpin_(Pss)诱导的烟草植株过敏反应和悬浮细胞的活性氧的释放及胞外碱性化。DIDS和A9C还可以抑制harpin_(Pss)诱导的Ca~(2 )内流。而且DIDS的抑制效率比A9C高。推测质膜上的阴离子通道对钙离子通道有着正调节作用,harpin_(Pss)通过阴离子通道和钙离子通道介导的信号传导途径,调节胞内Ca~(2 )浓度,从而启动这些防卫反应。     

半量瑞替普酶溶栓后行转运PCI与直接转运PCI对急性ST段抬高型心肌梗死临床疗效的对比研究

目的:比较急性ST段抬高型心肌梗死(STEMI)使用半量瑞替普酶溶栓后行转运经皮冠脉介入治疗(PCI)与直接转运两种救治策略的临床效果。方法:回顾性分析2015年6月～2018年2月我院收治的100例STEMI患者的病历资料,根据救治方案不同分为易化PCI组(先在基层医院经半量瑞替普酶溶栓后再转运至我院行PCI,58例)、直接转运PCI组(拒绝在基层医院接受溶栓治疗而要求直接转运PCI,42例)。比较两组PCI前后血管再通率、PCI后无复流发生率和ST段回落率(STR)、住院期间主要不良心脏事件(MACE)及治疗期间出血并发症的发生情况及随访1年主要终点事件的发生情况。结果:入院后首次冠脉造影显示易化PCI组PCI前TIMI 3级血流者占32.7%(19/59),显著高于直接转运PCI组[14.3%(6/42),P0.05]。PCI后14 d时,易化PCI组TIMI 3级血流者占93.1%(54/58),较直接转运PCI组[90.5%(38/42)]差异无统计学意义(P0.05)。PCI后即刻冠脉造影显示易化PCI组无复流发生率为6.9%(4/58),较直接转运PCI组[21.4%(9/42)]显著降低(P0.05)。PCI后24 h时,易化PCI组STR值为(61.53±11.27)%,显著高于直接转运PCI组[(52.40±12.63)%,P0.05]。住院期间,易化PCI组MACE发生率为10.3%(6/58),较直接转运PCI组[14.3%(6/42)]差异无统计意义(P0.05)。治疗期间,易化PCI组出血并发症总发生率为19.0%(11/58),与直接转运PCI组的14.3%(6/42)相比差异亦无统计学意义(P0.05)。随访1年,易化PCI组主要终点事件发生率为19.0%(11/58),显著低于直接转运PCI组[40.5%(17/42),P0.05]。结论:与直接转运PCI相比,STEMI患者应用半量瑞替普酶溶栓后行转运PCI有利于早期开通梗死血管,提高介入干预效果,PCI后获得优异的心肌灌注水平,从而改善远期预后,且安全性相当。     

miR-155通过下调BMP9/Smad信号通路抑制间充质干细胞C3H10T1/2成骨分化

该文研究了在诱导小鼠间充质干细胞C3H10T1/2细胞成骨分化过程中miR-155的作用及其是否是通过调控BMP9/Smad(bonemorphogenetic protein 9/drosophila mothers against de-capentaplegic)信号通路发挥作用。在诱导C3H10T1/2细胞成骨分化过程中,采用实时定量PCR(Real-time quantitative PCR,q RT-PCR)检测miR-155水平的变化。转染miR-155模拟剂(miR-155)至C3H10T1/2细胞后,miR-155水平显著增高(P0.001),而转染其抑制剂(anti-miR-155)至C3H10T1/2细胞后,miR-155水平显著降低(P0.001)。转染后成骨诱导培养基诱导成骨7 d,碱性磷酸酶(alkaline phosphatase,ALP)活性及染色结果显示,miR-155能显著降低C3H10T1/2细胞成骨分化过程中的ALP活性(P0.01)、减弱ALP染色,而anti-miR-155则能逆转其作用。成骨诱导14 d茜素红S染色结果显示,miR-155组钙盐结节较对照组少,下调miR-155的水平后,钙盐沉积结节增多。q RT-RCR检测结果显示,miR-155显著降低BMP9 m RNA水平(P0.001),且miR-155组成骨基因Runx2和ALP表达均显著低于对照NC组(P0.05、P0.01)。Western blot检测BMP9、Runx2和p-Smad1/5/8蛋白质水平,结果显示,miR-155组蛋白质水平均显著降低(P0.01、P0.05、P0.001)。该研究结果提示,miR-155对C3H10T1/2细胞成骨分化的抑制作用可能是通过抑制BMP9/Smad信号通路发挥作用的。     

SEMA3C/SEMA3D基因错义突变对蛋白稳定性和受体亲合力的影响

目的:明确先天性巨结肠患者携带的5个SEMA3C/SEMA3D基因错义突变对Semaphorin 3(Sema3)蛋白自身稳定性和受体亲合力的影响作用。方法:构建Sema3-Neuropilin-Plexin配体-受体复合物蛋白质模型,对全部5个错义突变进行定位,通过计算标准能量功能赋值(△△G)和复合物界面值(△I_sc)预测突变对Sema3的影响作用。将野生型和突变型AP-tagged Sema3质粒分别转染HEK293T细胞,72 h后收集含有融合蛋白的细胞培养液上清并与分别表达Neuropilin 1(Nrp-1)或Neuropilin 2(Nrp-2)的COS-7细胞孵育,洗脱未结合的蛋白后加入碱性磷酸酶底物显色拍片,或提取细胞总蛋白,利用融合蛋白N-末端含有的碱性磷酸酶在底物PNPP存在时可以发生颜色变化的特性,对与受体结合的野生型和突变型AP-Sema3蛋白进行定量。结果:5个错义突变中的4个都会不同程度地影响相应Semaphorin 3蛋白与其受体Neuropilin的结合(与Nrp-1的结合:SEMA3C S329G,V337M,SEMA3D H424Q,V457I,P615T分别与野生型相比:1.12±0.15,0.37±0.03,0.56±0.07,0.51±0.05,0.66±0.05;与Nrp-2的结合:SEMA3C S329G,V337M,SEMA3D H424Q,V457I,P615T分别与野生型相比:1.18±0.09,0.37±0.03,0.76±0.01,0.65±0.06,0.85±0.03,n=3,单因素方差分析,差异有统计学意义),说明它们可能通过严重影响分子通路的信号转导而妨碍蛋白功能的正常行使。结论:先天性巨结肠患者携带的SEMA3C/SEMA3D基因错义突变可不同程度影响蛋白与其受体的结合,提示Semaphorin 3这类经典的神经元轴突导向因子在功能失常的情况下可能参与先天性巨结肠的发生。     

BaP通过AhR抑制BMP2诱导的间充质干细胞C3H10T1/2成骨分化

该文主要研究苯并芘(benzoapyrene,Ba P)对骨形态发生蛋白2(bone morphogenetic protein 2,BMP2)介导的间充质干细胞C3H10T1/2细胞成骨分化的影响,并探究这种作用的调控机制。用腺病毒Ad-BMP2感染C3H10T1/2细胞,RT-PCR检测到BMP2的表达水平显著增高(P0.001),芳香烃受体(aryl hydrocarbon receptor,Ah R)的表达则无显著差异。随后加入不同浓度Ba P处理,检测Ba P对BMP2诱导的C3H10T1/2细胞成骨分化的影响,处理7天检测碱性磷酸酶(alkaline phosphatase,ALP)的染色和活性,14天检测茜素红S染色。结果显示,Ba P可以剂量依赖的方式抑制BMP2介导的ALP和钙盐沉积(P0.001);Western blot检测结果显示,Ba P可以剂量依赖的方式抑制BMP2诱导的p-Smad1/5/8(p-drosophila mothers against de-capentaplegic 1/5/8)及Runx2的表达(P0.01,P0.001)。应用Ah R拮抗剂CH223191后,测定结果显示,其可部分逆转Ba P对BMP2诱导的C3H10T1/2细胞早晚期成骨分化及BMP2/Smad信号通路的抑制作用(P0.05,P0.001)。该研究结果提示,Ba P可通过Ah R抑制BMP2介导的促进间充质干细胞C3H10T1/2细胞成骨分化,这一过程与BMP2/Smad信号通路受到抑制有关。     

Ca2+在水杨酸诱发的丹参培养细胞培养基碱化过程中的作用

利用质膜钙离子通道抑制剂LaCl3、异搏定(Verapamil,VP),钙离子载体A23187,内膜系统钙离子通道抑制剂2-APB和LiCl处理,研究水杨酸(SA)诱发的丹参培养细胞内Ca2+迸发在培养基碱化过程中的作用。结果显示:SA处理诱发丹参培养细胞培养基碱化,质膜钙离子通道抑制剂LaCl3和VP、内膜系统钙离子通道抑制剂2-APB和LiCl单独处理均可显著抑制SA处理诱发的培养基碱化过程,但质膜钙离子通道抑制剂对SA处理诱发的培养基碱化的抑制作用要显著强于内膜系统钙离子通道抑制剂;当两类钙离子通道抑制剂同时使用,培养基碱化过程被完全抑制,甚至培养基出现酸化趋势;钙离子载体A23187可以显著促进培养基碱化过程。以上结果说明,由水杨酸诱发的胞外Ca2+内流与胞内钙库Ca2+释放均参与了丹参培养基碱化的诱导过程,但胞外Ca2+内流的作用更重要。本研究揭示了SA诱发的Ca2+与丹参细胞培养基碱化之间的关系,为更深层次地阐明植物次生代谢调控机制提供理论基础。     

比较不同浓度舒芬太尼靶控输注在清醒气管插管中的应用

目的:比较清醒气管插管中不同浓度舒芬太尼靶控输注对血流动力学及应激反应的影响,探讨舒芬太尼应用于清醒气管插管中的最适靶控浓度。方法:择期困难气道患者80例,随机分为四组,每组20例:A组为对照组,静注生理盐水,B、C、D组分别接受舒芬太尼0.1 ng/m L、0.3 ng/m L、0.5 ng/m L效应室靶控输注,记录入室后(T0),达到设定血药浓度时(T1)、气管插管时(T2)和气管插管后(T3)的收缩压(SBP)、舒张压(DBP)、心率(HR)、血氧饱和度(Sp O2),分别于入室后、插管后3 min、5 min采血测皮质醇浓度。结果:1SBP:T1时,B、C、D组均有不同程度的降低(P0.05),T3时A、B组明显升高(P0.05);2DBP:T2时A、B组升高显著(P0.05),C、D组无较大变化(P0.05);3HR:T1时B、C、D均下降,D组下降最明显,与A、B、C三组比较差异有统计学意义(P0.05);T2时A、B组HR升高(P0.05),C、D组插管前后变化不明显(P0.05);4Sp O2:组间、组内比较差异有统计学意义(P0.05);5皮质醇:插管后三分钟C、D组较A组降低(P0.05),C、D组内五分钟、三分钟同入室后比较皮质醇降低(P0.05)。结论:0.3 ng/m L效应室浓度(ce)的舒芬太尼靶控输注可以有效的减弱清醒气管插管所致的应激反应,0.3ng/ml以上效应室浓度的舒芬太尼能将心血管反应抑制得更加完全。     

Simultaneous analysis of disopyramide and quinidine in plasma by high-performance liquid chromatography

A new reversed-phase high-performance liquid chromatographic method allowing simultaneous measurement of plasma concentrations of disopyramide and quinidine is described. Disopyramide and quinidine were separated on a reversed-phase column using 0.05 M phosphate buffer (pH 3.0)—acetonitrile (73:27, v/v), as mobile phase and the peaks were monitored by UV absorbance at the wavelengths of 254 and 325 nm. The drugs were extracted from alkaline plasma with chloroform containing the internal standard. The organic phase was evaporated to dryness and the residue was redissolved in a small volume of the mobile phase before analysis by high-performance liquid chromatography. The method is convenient and reliable in routine monitoring of both drugs.     

Calcium equilibrium in muscle

1. A study of the calcium equilibrium in isolated frog muscle has been attempted. 2. When sartorius muscles were immersed in Ca(45) Ringer's solution, the surface phase took up the Ca(45) in about 1 minute; the extracellular water space and connective tissue in about 30 minutes; and the intracellular space in about 300 minutes. 3. The percentages of total calcium in the whole muscle immersed in Ringer's solution was as follows: 10 per cent in the surface phase; 12 per cent in the extracellular water space; 17 per cent in the dry connective tissue; 24 per cent in the intracellular space; and 37 per cent as non-exchangeable calcium. 4. The exchange constants of isolated frog sartorius muscle to calcium has been determined. The flux of intracellular calcium in the steady state was approximately 0.8 mM/(liter hr). 5. It appears that there is a calcium pump pushing calcium out of the cell against an electrochemical gradient of about 4 cal./mM of calcium. However, since the flux is low, the maximum energy required per hour to pump calcium out of the cell against this high gradient is only about 2 cal./kg. muscle or about 1 per cent of the resting energy.     

The effects of calmodulin antagonist drugs on isolated sarcoplasmic reticulum from malignant hyperpyrexia susceptible swine

1. Because calcium antagonist drugs increase contracture in both control and malignant hyperpyrexia susceptible (MHS) skeletal muscle, the effect of these drugs on the sarcoplasmic reticulum (SR) was investigated. 2. The calmodulin antagonist drugs inhibited the Ca2+ dependent ATPase activity and the ATP-dependent Ca2+ uptake, and accelerated the efflux of Ca2+ from isolated SR preparations from both control and MHS skeletal muscle. These effects of calmodulin antagonist drugs on SR Ca2+ transport functions were consistent with their in vitro pharmacological effects on control and MHS muscle.     

Conversion of beating to bursting pacemaker activity: Action of quinidine

External quinidine converts the pacemaker neurone L-11, found in the Aplysia abdominal ganglion, from spontaneously "beating" to "bursting" discharge activity. Quinidine-induced bursting ceased when entry of Ca2+ ions into the cells was blocked in a Ca2+-free, Co2+-containing solution or if internal Ca2+ accumulation was prevented by the injection of EGTA. The analysis of membrane currents from voltage clamp experiments showed that quinidine blocks the Ca2+ inward current in a dose- and time-dependent manner. In addition, the currents were displaced to the left on the voltage axis, causing an increase of the inward current at negative membrane potentials. External quinidine suppresses the Ca2+-activated K+ current induced by intracellular Ca2+ injections and acts to prolong its decay phase. The slowing of the decay phase of the Ca2+-activated K+ current by quinidine was prevented after intracellular injection of EGTA, indicating that Ca2+ removal is impaired by the drug. It is suggested that the increase of Ca2+ inward current at negative potentials and the prolonged activation of the Ca2+-activated K+ current play a major role in causing the bursting discharge behavior in normally beating cells.     

Cationic specificity of a Ca2+-accumulating system in smooth muscle cell mitochondria

In the experiments conducted with application of an isotopic technique (45Ca2+) on the myometrium cells suspension treated by digitonin solution (0.1 mg/ml) some properties of Ca ions accumulation system in the mitochondria--cationic and substrate specificity as well as effects of Mg2+ and some other bivalent metals ions on the Ca2+ accumulation velocity have been estimated. Ca ions accumulation from the incubation medium containing 3 mM sodium succinate Na, 2 mM Pi (as potassium K(+)-phosphate buffer, pH 7.4 at 37 degrees C), 0.01 mM (40CaCl2 + 45CaCl2) and 100 nM thapsigargin--selective inhibiting agent of endoplasmatic reticulum calcium pump were demonstrated as detected just only in presence of Mg, while not Ni, Co or Cu ions. The increase of Mg2+ concentration from 1 x 10(-6) to 10(-3) M induced the ATP dependent transport activation in the myometrium mitochondria. Under [Mg2+] increase till 40 mM this cation essentially decreased Ca2+ accumulation (by 65% from the maximal value). The optimum for Ca2+ transport in the myometrium cells suspension is Mg2+ 10 mM concentration. Ka activation apparent constant along Mg2+ value (in presence 3 mM ATP and 3 mM sodium succinate) is 4.27 mM. The above listed bivalent metals decreased Mg2+, ATP-dependent accumulation of calcium, values of inhibition apparent constants for ions Co2+, Ni2+ and Cu2+ were--2.9 x 10(-4) M, 5.1 x 10(-5) M and 4.2 x 10(-6) M respectively. For Mg2+, ATP-dependent Ca2+ transport in the uterus myocytes mitocondria a high substrate specificity is a characteristic phenomenon in elation to ATP: GTP, CTP and UTP practically fail to provide for Ca accumulation process.     

The distribution and kinetics of release of radiocalcium in tendon and skeletal muscle

The distribution of Ca(45) in frog (Rana pipiens) sartorius muscle, after 4 hours' exposure to Ringer's solution containing radiocalcium, has been analyzed by observing the kinetics of escape of the radioisotope into a non-radioactive Ringer's solution with calcium present or absent and by assuming that the tendon of Achilles is a satisfactory model of the extent of the uptake and release of Ca(45) by the interstitial connective tissue (c.t.). In a Ringer's solution containing 1 mM/liter calcium, the exchangeable calcium distribution in micromoles per gram wet weight is as follows: (a) Aqueous phase of c.t. space: 0.16; (b) bound to c.t.: 0.16; (c) bound to surface of fibers: 0.13, of which 0.03 is displaced only by self-exchange, whereas the rest, as in c.t., can be displaced by other ions; and (d) in myoplasm: 0.33. The kinetics of Ca(45) exit suggests that in infinite time of exposure to Ca(45) the myoplasmic component would rise to 0.85. In the muscles, the half-time of the quickly emerging Ca(45) averages about 3 minutes, whereas the time constant of the slowly released component is about 500 minutes. In the tendons the percentage rate of escape falls exponentially, the half-time of emergence being about 10 minutes.     

The metal sites on sarcoplasmic reticulum membranes that bind lanthanide ions with the highest affinity are not the ATPase Ca2+ transport sites.

We attempted to establish whether lanthanide ions, when added to sarcoplasmic reticulum (SR) membranes in the absence of nucleotide, compete with Ca2+ for binding to the transport sites of the Ca(2+)-ATPase in these membranes, or whether they bind to different sites. Equilibrium measurements of the effect of lanthanide ions on the intrinsic fluorescence of SR ATPase and on 45Ca2+ binding to it were performed either at neutral pH (pH 6.8), i.e. when endogenous or contaminating Ca2+ was sufficient to nearly saturate the ATPase transport sites, or at acid pH (pH 5.5), which greatly reduced the affinity of calcium for its sites on the ATPase. These measurements did reveal apparent competition between Ca2+ and the lanthanide ions La3+, Gd3+, Pr3+, and Tb3+, which all behaved similarly, but this competition displayed unexpected features: lanthanide ions displaced Ca2+ with a moderate affinity and in a noncooperative way, and the pH dependence of this displacement was smaller than that of the Ca2+ binding to its own sites. Simultaneously, we directly measured the amount of Tb3+ bound to the ATPase relative to the amount of Ca2+ and found that Tb3+ ions only reduced significantly the amount of Ca2+ bound after a considerable number of Tb3+ ions had bound. Furthermore, when we tested the effect of Ca2+ on the amount of Tb3+ bound to the SR membranes, we found that the Tb3+ ions which bound at low Tb3+ concentrations were not displaced when Ca2+ was added at concentrations which saturated the Ca2+ transport sites. We conclude that the sites on SR ATPase to which lanthanide ions bind with the highest affinity are not the high affinity Ca2+ binding and transport sites. At higher concentrations, lanthanide ions did not appear to be able to replace Ca2+ ions and preserve the native structure of their binding pocket, as evaluated in rapid filtration measurements from the effect of moderate concentrations of lanthanide ions on the kinetics of Ca2+ dissociation. Thus, the presence of lanthanide ions slowed down the dissociation from its binding site of the first, superficially bound 45Ca2+ ion, instead of specifically preventing the dissociation of the deeply bound 45Ca2+ ion. These results highlight the need for caution when interpreting, in terms of calcium sites, experimental data collected using lanthanide ions as spectroscopic probes on SR membrane ATPase.     

The Effect of Quinidine on Calcium Accumulation by Isolated Sarcoplasmic Reticulum of Skeletal and Cardiac Muscle

Quinidine potentiates twitch tension and (at higher concentrations) causes contracture of skeletal muscle whereas the same drug reduces tension development of cardiac muscle. To gain insight into the possible differences in the excitation-contraction coupling mechanism of the two types of muscle the effect of quinidine on calcium accumulation by isolated sarcoplasmic reticulum from skeletal and cardiac muscle was investigated. In a medium containing ATP, Mg⁺⁺, oxalate, and ⁴⁵Ca, pharmacologically active concentrations of the drug inhibited calcium accumulation by both skeletal and cardiac sarcoplasmic reticulum. The inhibition of the rates of calcium, uptake by the skeletal muscle preparation ranged from 11% with 10^-4 M quinidine to 90% with 10^-3 M quinidine. With the cardiac muscle preparation the inhibition ranged from 16% with 3 x 10^-6 M quinidine to 100% with 10^-3 M quinidine. With both preparations the inhibition of calcium transport was accompanied by an inhibition of the Ca⁺⁺-activated ATPase activity of the sarcoplasmic reticulum. The effect of quinidine on the skeletal sarcoplasmic reticulum supports the hypothesis that this compound produces twitch potentiation and contracture by interfering with intracellular calcium, sequestration. Its effect on cardiac sarcoplasmic reticulum. has been interpreted in terms of the hypothesis that cardiac contractility is a function of the amount of calcium released from the sarcoplasmic reticulum which is in turn dependent upon the absolute calcium content of the reticulum. Hence, following inhibition of calcium transport there would be less calcium available for coupling.     

甘肃黑蛋巢抗松梢枯病菌物质的分离纯化及抑菌活性*

采用MS培养基培养甘肃黑蛋巢Cyathus gansuensis,以生测为导向,乙酸乙酯和氯仿从甘肃黑蛋巢MS培养液中萃取出抗菌活性组分。Rp-18反相色谱柱和高效液相色谱仪相结合,从抗菌代谢产物分离纯化出一种抗松梢枯病菌(Sphaeropsis sapinea)的活性物质CXL-I,高效液相色谱检测表明CXL-I为一纯物质。CXL-I对松梢枯病菌的菌丝生长和孢子萌发有较强的抑制活性,当CXL-I浓度为50礸/ml时对菌丝生长抑制率可达80%,对孢子萌发抑制率达95%以上。     

1,25-Dihydroxyvitamin D3 stimulates 45Ca2+ uptake by cultured adult rat ventricular cardiac muscle cells

This study tested the hypothesis that 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and its previously described cardiac receptors play roles in regulating intracellular calcium homeostasis in cardiac muscle cells. This question was addressed by assessing whether 1,25-(OH)2D3 influences 45Ca2+ uptake by homogeneous cultures of adult rat ventricular cardiac muscle cells. Twenty-four h prior to the measurement of 45Ca2+ uptake, the cells were transferred to serum-free medium ([Ca2+], 1.0 mM) containing 1.0 nM 1,25(OH)2D3 or vehicle. The cells were then incubated with 45Ca2+ for periods up to 60 min at room temperature, followed by removal of excess external 45Ca2+ by washing repeatedly with La3+. Pretreating the cells with 1,25-(OH)2D3 caused 3-fold stimulation (p less than 0.005) of 45Ca2+ uptake. Stimulation of 45Ca2+ uptake required a prolonged (8-12 h) exposure to 1,25-(OH)2D3, suggesting a receptor-mediated phenomenon. Concentrations of 0.01-10 nM 1,25-(OH)2D3 yielded a dose-response curve which peaked at 1.0 nM and decreased at higher concentrations. Steroid specificity was established by the failure of 1.0 nM levels of 25-hydroxyvitamin D3, estradiol-17 beta, and progesterone to change 45Ca2+ uptake. Sucrose gradient analysis confirmed the presence of a specific 3-4 S 3H-1,25-(OH)2D3 binding component both in freshly isolated and in cultured ventricular cardiac muscle cells. The stimulatory effect of 1,25-(OH)2D3 on 45Ca2+ uptake was abolished by the concomitant incubation of the cells with cycloheximide or actinomycin D, demonstrating a requirement for protein and nucleic acid synthesis. In conclusion, these data demonstrate that 1,25-(OH)2D3 stimulates 45Ca2+ uptake in adult ventricular cardiac muscle cells by a mechanism resembling a receptor-mediated phenomenon.