Excitation of locus coeruleus neurons by an adenosine 3',5'-cyclic monophosphate-activated inward current: extracellular and intracellular studies in rat brain slices

The firing rate of locus coeruleus (LC) neurons in rat brain slices was increased reversibly by agents that either elevate intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) or mimic its actions (e.g., forskolin, and activator of adenylate cyclase, 8-Br-cAMP, a membrane permeable analog of cAMP, and Ro20-1724, a preferential inhibitor of cAMP-phosphodiesterase). Intracellular recordings showed that 8-Br-cAMP and forskolin induce a depolarization of LC neurons, accompanied by a decrease in input resistance. The 8-Br-cAMP- and forskolin-elicited depolarization persisted in the presence of cobalt, a calcium channel blocker. Steady-state current-voltage curves revealed that in the voltage range of -50 to -120 mV, 8-Br-cAMP and forskolin induced an inward current, which did not reverse at the potassium equilibrium potential and could not be blocked by tetrodotoxin. Partial replacement of sodium with Tris or choline markedly reduced the depolarization elicited by 8-Br-cAMP. We conclude that 8-Br-cAMP and forskolin act through a common mechanism to increase the firing rate of locus coeruleus neurons by inducing a cAMP-activated inward current, carried out at least in part by sodium ions.     

A neosynthesis of sodium channels is involved in the evolution of the sodium current in isolated adult DUM neurons

Short-term culture of isolated adult dorsal unpaired median (DUM) neurons of the cockroach Periplaneta americana has been used to study the evolution of the sodium current during the time in culture after axotomy and deafferentation treatment. An increase in the maximum peak amplitude of the sodium current recorded under voltage-clamp conditions with the patch-clamp technique in the whole-cell recording configuration, was only observed between 24h and 72h (75%) without any modification of the kinetics and the voltage-dependence of the current. A decrease in the level of foetal calf serum in the culture medium reduces the amplitude of the sodium current on all days but does not affect its time-course of development which was on the contrary completely abolished by both protein synthesis inhibitors, actinomycin D and cycloheximide. The results obtained in these neurons strongly suggest that a neosynthesis of sodium channel proteins is involved in the evolution of the sodium current induced by axotomy and deafferentation.     

Repetitive firing properties in subpopulations of the chick Edinger Westphal nucleus.

The avian Edinger Westphal nucleus, through the ciliary ganglion, controls accommodation, iris constriction, and blood flow through the choroid. In live brainstem slices, the nucleus is easily identifiable as an olive-shaped cluster of neurons dorsal to the oculomotor nerve and nucleus. Intracellular recordings from neurons in the nucleus identified two classes of responses to sustained (300 to 500 ms) injections of depolarizing current. One set of cells fired action potentials for the duration of the pulse while a second set of cells fired action potentials only transiently, during the first 50 to 100 ms, after which they remained silent regardless of the size of the depolarization. Intracellular recordings followed by injections of the fluorescent dye lucifer yellow revealed that repetitively firing cells were located in the lateral half of the nucleus while non-repetitively or transiently firing cells were located in the medial half. These locations correspond to different Edinger Westphal subdivisions which have distinct inputs and target populations. The varying firing patterns are discussed with reference to the known functions of the subdivisions in which they occur. Replacement of calcium by magnesium in the extracellular medium had no effect on the number of action potentials fired by non-repetitively firing cells, suggesting that a calcium-activated potassium current is not responsible for suppressing repetitive firing in these cells. In contrast, in repetitively firing cells removal of extracellular calcium increased the frequency of action potential discharge and decreased the amplitude of afterhyperpolarizations following single action potentials. Addition of cadmium to the bath medium had similar effects.(ABSTRACT TRUNCATED AT 250 WORDS)     

单向中频电加助透液防治瘢痕增生

为防治瘢痕增生，寻求有效治疗方法，我们采用单向中频电加助透液治疗瘢痕增生患者３３例，痊愈显效率为６４％，总有效率为８８％。结果表明，单向中频电加助透液能增强导入作用，是防治瘢痕增生的有效方法。     

沂蒙山区医院医疗质量管理现状调查

目的：调查本地区医疗质量管理现状，研究提高医疗质量的对策。方法：采用分层抽样调查方法，对本区域24所不同级别医院的医疗质量进行全面调查。结果：各医院在门(急)诊管理、医技、临床医疗、感染控制、护理管理等方面都不同程度地存在医疗质量缺陷。结论：落实各项规章制度，强化医疗服务，提高医护质量，确保医疗安全。     

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.     

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     

Variability of the pattern electroretinogram

Conflicting results have been obtained concerning the parametric properties of the pattern electroretinogram. These discrepancies may be due to the large amount of variability inherent in recording amplitudes. We have found the variability within a single stimulus condition to be so large (ranging from 30% to 67% of the mean value) that it could mask any underlying spatial frequency tuning. Changing the stimulus conditions failed to significantly reduce the observed variability, although changing recording conditions produced some reduction. The use of a narrower rejection band, a greater number of sweeps, and placement of the reference electrode on the ipsilateral ear (as opposed to the ipsilateral temple) combined to decrease variability of the pattern electroretinogram within a single recording session; however, intersession variability remained high. Therefore one must be careful in evaluating data from this technique, and caution is advised in its clinical use.     

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.