对不同月龄雄性大鼠成骨细胞内钙和钙通道电流的实验研究

目的研究不同月龄的雄性大鼠成骨细胞内钙浓度及钙通道电流是否存在差异.方法采用二次酶消化法分离不同月龄(分别为1、2、3、5、7、9、11、13、15)雄性大鼠的原代成骨细胞,通过激光扫描共聚焦技术测定细胞内游离钙浓度([Ca2+]i)(以平均荧光强度表示),同时应用全细胞膜片钳技术记录成骨细胞膜钙电流(ICa)的变化.结果共聚焦结果显示随月龄增加,成骨细胞内[Ca2+]i逐渐降低,但相邻2月龄组之间细胞内[Ca2+]i无显著性差异(P＞0.05);1、2、3月龄组与11、13、15月龄组成骨细胞内[Ca2+]i有显著性差异(P＜0.05),5、7、9月龄组与各组相比均无差异(P＞0.05).应用全细胞膜片钳技术发现刺激电压为+10 mV时,2、7、13月龄组鼠ICa分别为(-392.77±97.07)pA、(-330.33±33.86)pA和(-287.68±71.01)pA,13月龄组鼠与2月龄组鼠相比,ICa明显降低(P＜0.05),而7月龄组鼠与2月龄组鼠和13月龄组鼠相比,ICa均没有明显差异(P＞0.05).结论不同月龄大鼠成骨细胞内[Ca2+]i存在差异,其机制可能与细胞膜上钙通道活性改变相关.     

射频消融治疗室上性心动过速10例报告

作者报告了１０例室上性心动过速，共１１条径路的射频消融的成功经验。介绍了左侧显性旁路、隐匿性旁路及房室结双径路射频导管改良的基本方法以及定位标准。     

Substance P augments a persistent slow inward calcium-sensitive current in voltage-clamped spinal dorsal horn neurons of the rat

Rat spinal dorsal horn neurons in slice preparations perfused with Ringer solution containing 0.5-1 microM TTX and/or 10-20 mM tetraethylammonium at 29 degrees C, were studied by using a single microelectrode voltage-clamp technique. Slow persistent inward currents were recorded during depolarizing voltage commands to membrane potentials positive to about -40 mV. The inward current was depressed by removing external Ca, or by adding 0.1-0.2 mM Cd, 5 mM Co or 0.1 mM verapamil, and was increased by adding Ba or Bay-K 8644. Substance P (SP) augmented a persistent slow inward Ca-sensitive current in a dose-dependent manner. It is suggested that this effect may be instrumental in generating the SP-evoked slow depolarization, increase in membrane excitability, and the 'bursting' behavior in the immature rat dorsal horn neurons. In addition, in some neurons SP reduced the M-like current, which effect may contribute to, but not explain, generation of the SP-induced slow depolarization.     

微电流与低浓度氯对水中脊髓灰质炎I型病毒的协同灭活效应

目的　观察微电流 (low amperage direct current,LDC)与游离氯 (free chlorine,FC)对水中脊髓灰质炎 I型病毒 (PV1 )的协同灭活效果 .方法　用微电流 0 .4～ 1 .2 m A·cm-2 协同氯 0 .2～ 0 .3 mg· L-1 处理污染 PV1水样 ,比较作用前后灭活率 K值评价灭活效果 ,用 Berenbaum方法判断微电流与氯灭活病毒有无协同效应 ,用蚀斑形成试验 (PFUA)和病毒细胞酶联免疫试验 (VELCIA)检测感染性和抗原性变化 .结果　实验观察到微电流达到 0 .4 m A· cm-2 对水中PV1有弱灭活作用 ,电流密度达到 1 .2 m A· cm-2 与 0 .2mg· L-1氯有协同灭活效应 ,微电流 1 .2 m A· cm-2与氯 0 .3mg· L-1协同消毒 30 min,水中病毒减少 4.0 8个对数级 ,而单独用氯仅减少 1 .93个对数级 ;协同作用后病毒感染性灭活增强 ,而抗原性灭活不明显 .结论　微电流协同氯可提高低浓度氯灭活水中病毒的效果     

The Effect of 50 Hz External Electrical Interference on Implanted Cardiac Pacemakers

The effects of injected 50 Hz alternating current on the function of cardiac pacemakers has been observed in 18 patients with implanted unipolar VVI units. Current, in the range 0-600 microA was applied via electrodes attached to the patients' upper body and feet and fed from a specially designed current injection unit at the bedside. Most implanted pacemakers reverted to interference mode in the current range 29-250 microA. At current levels just below the reversion current all units developed irregular and inappropriate pacing. This current level was pacemaker dependent and varied in the range 27-246 microA. The total reversion current depended on the location of the injecting electrodes and on the patients' posture. The sensitivity of the units to injected interference was increased by deep inspiration. Temporary pacing catheters fitted to an additional ten patients were used to monitor the interference voltage which would be sensed by an implanted unit. This voltage was similarly dependent on patient posture and on deep respiration. Current injection has proved to be a safe, controllable and reproducible method of testing the sensitivity of implanted pacemakers to 50 Hz external interference.     

顽固性室性早搏的射频消融治疗

目的 :通过对 2 3例顽固性室性早搏 (简称室早 )的射频消融分析 ,探讨室早的心电图特点、消融方法及效果 .方法 :男性 16例 ,女性 7例 ,均为频发、药物难治、症状明显的顽固性单形性室早患者 ,年龄(4 4 4± 9 6 )岁 .采用起搏标测和激动顺序标测 ,前者以起搏时与室早QRS波形态完全相同点为消融靶点 ,后者以早搏时最早心室激动点为消融靶点 .2 3例中 17例室早起源于右室 ,4例起源于左室 .消融即刻成功率86 9% ,累积放电 (930 4± 72 5 )s,成功者行动态心电图检查记录消融前后室早数为 (5 6 71± 2 4 36 )次 / 2 4h和 (39± 5 2 )次 / 2 4h (P <0 0 1) .随访 (2 3 2± 12 3)月 ,未服任何抗心律失常药 ,无 1例复发及并发症发生 .结论 :射频消融可有效而安全地消除单形性室早 ,采用粗标激动顺序、精标起搏图形 ,多点、长时间、高功率放电可提高成功率 ,降低复发率 ,可作为症状严重、药物无效或不能耐受患者的治疗选择     

复发性自然流产患者绒毛滋养细胞FasL的表达

目的探讨复发性自然流产患者(RSA)绒毛滋养细胞FasL的表达与正常者有无差异。方法应用免疫组化和RT-PCR法,检测RSA患者和正常早孕妇女的绒毛滋养细胞FasL在蛋白水平和mRNA水平的表达,并进行图象分析和比较。结果免疫组化结果显示,绒毛合体滋养细胞和细胞滋养细胞的胞浆和胞膜上均有FasL表达,FasL在2组的定位无差异,但正常组绒毛滋养细胞FasL表达(PU=18.03±4.69)强于RSA组(PU=13.59±3.73),P<0.050。RT-PCR结果表明RSA组绒毛组织FasL在mRNA水平的表达为0.18±0.05,低于正常组0.27±0.06,差异有显著性意义(P<0.01)。结论不明原因RSA患者的绒毛滋养细胞FasL表达弱于正常者,滋养细胞FasL的表达减少可能在复发性自然流产中起重要作用。     

Differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive and tetrodotoxin-resistant single sodium channels

The differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) single sodium channel currents in rat dorsal root ganglion (DRG) neurons were investigated using the outside-out configuration of patch-clamp technique. Channel conductances were 10.7 and 6.3 pS for TTX-S and TTX-R sodium channels, respectively, at a room temperature of 24–26°C. The single-channel current of TTX-S sodium channels at the test potential of −30 mV was −1.27 ± 0.25 pA, and was not changed after exposure to 10 μM tetramethrin (−1.28 ± 0.23 pA). The open time histogram of TTX-S single-channel currents could be fitted by a single exponential function with a time constant of 1.27 ms. After exposure to 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 1.36 ms (τ_fast) and 5.73 ms (τ_low). The percentage of contribution of each component to the population was 62% for the fast component representing the normal channels and 38% for the slow component representing the tetramethrin modified channels. The amplitudc of TTX-R single-channel currents was slightly changed from −0.72 ± 0.14 to −0.83 ± 0.07 pA by 10 μM tetramethrin. The open time histogram of TTX-R single-channel currents could be fitted by a single exponential function with a time constant of 1.92 ms. In the presence of 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 2.07 ms (τ_fast) and 9.75 ms (τ_slow). The percentage of contribution of each component was 15% for the fast, unmodified component and 85% for the slow, modified component. Differential effects of tetramethrin on the open time distribution of single sodium channel currents explains the differential sensitivity of TTX-S and TTX-R sodium channels.     

The Cardiac Pacemaker Current if

Pacemaker Current if. Since the hyperpolarization-activated current, if, was originally associated with the diastolic depolarization phase of action potential in the sinoatrial (SA) node in 1979, its central role in the generation and control of pacemaker activity has become increasingly clear through a series of experimental findings, some of which have substantially modified the pre-existing theories of cardiac pacemaking and its modulation by the autonomic transmitters. Thus, the pacemaker current of Purkinje fibers, formerly described as a deactivating pure potassium (K) current, was found to be in fact, like the nodal if, inward and activating on hyperpolarization. Furthermore, in SA node cells, as well as mediating rhythm acceleration induced by catecholamines, if was found to underlie the slowing effect of low acetylcholine (ACh) concentrations, in contrast with the generally accepted hypothesis that activation of a K conductance is the main process responsible for cardiac slowing. A final, atypical property of if recently demonstrated concerns the activating action exerted on if by intracellular cAMP. Unlike that on other voltage-gated, cAMP-modulated cardiac channels, this action is independent of phosphorylation and involves a direct binding of cAMP to if channels. (J Cardiovasc Electrophysiol, Vol. 3, pp. 334–344, August 1992)