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101.
Angela Ameri 《Naunyn-Schmiedeberg's archives of pharmacology》1997,355(2):273-280
The effects of the Aconitum alkaloid 3-acetylaconitine on neuronal activity were investigated in the slice preparation and on cultivated neurons of rat
hippocampus by extracellular and patch-clamp recordings, respectively. 3-Acetylaconitine (0.01–1 μM) diminished the orthodromic
and antidromic population spike in a concentration-dependent manner. The inhibitory action of the drug was preceded by a transiently
enhanced excitability. The latency of onset of the inhibition was accelerated by increased stimulation frequency, whereas
recovery during washout of the alkaloid was accelerated by decreased stimulation frequency. Moreover, the inhibitory effect
of 3-acetylaconitine was evaluated in two different models of epileptiform activity induced either by blockade of GABA receptors
by bicuculline (10 μM) or by a nominal Mg2+-free bathing medium. In accordance with the activity-dependent mode of action, this compound abolished the synaptically evoked
population spikes in the presence of bicuculline or nominal Mg2+-free bathing medium, respectively. Whole-cell patch-clamp recordings revealed an interaction of 3-acetylaconitine with the
voltage-dependent sodium channel. At a concentration of 1 μM, 3-acetylaconitine did not affect the peak amplitude of the sodium
current, but shifted the current-voltage relationship in the hyperpolarized direction such that sodium currents were already
activated at the resting potential.
Received: 22 July 1996 / Accepted: 14 October 1996 相似文献
102.
Y. Naito Y. Ohtawara S. Kageyama M. Nakano A. Ichiyama M. Fujita K. Suzuki K. Kawabe I. Kino 《Urological research》1997,25(1):59-65
Cell culture models of calcium phosphate renal stone formation were established using the MDCK cell line. Renal microliths were detected within pseudocysts in three-dimensional soft agar cultures, and were also observed in the basal region of cells lining the cell sheet, and immediately beneath domes or blisters in monolayers and collagen gel cultures. Light and scanning electron microscopy indicated that these microliths had a similar lamellated and spherical appearance to those in humans. These microliths were first detected microscopically after 21 days of culture, and were found to be composed of calcium phosphate by X-ray and microinfrared spectroscopic analyses. These culture models may provide a powerful new tool to study the pathogenesis of renal stone diseases and/or calcium phosphate stone formation in humans and animals. 相似文献
103.
吡那地尔对体外培养大鼠大脑皮层神经细胞缺氧缺糖损伤的保护作用 总被引:1,自引:0,他引:1
目的 :探讨ATP敏感性K+ 通道 (KATP)开放剂吡那地尔 (pinacidil,Pin)对缺氧缺糖再复氧损伤大鼠大脑皮层神经细胞的保护作用。方法 :体外培养大鼠大脑皮层神经细胞 ,细胞培养至 10d ,建立神经细胞缺氧缺糖损伤模型 ,观察Pin及KATP阻断剂格列苯脲对缺氧缺糖不同时间 ,再复氧 2 4h后细胞死亡率、丙二醛 (MDA)含量、超氧化物歧化酶 (SOD)活力的影响。结果 :缺氧缺糖、再复氧后大鼠的神经细胞死亡率均显著升高、MDA生成增多、SOD的活力下降 ,Pin干预后 ,细胞死亡率下降、MDA生成减少、SOD的活力升高 ;格列苯脲能拮抗Pin这种保护作用。结论 :Pin对缺氧缺糖损伤神经细胞具有保护作用 ,并与拮抗氧自由基有关 相似文献
104.
Joel A. Black Ruth Westenbroek Bruce R. Ransom William A. Catterall Stephen G. Waxman 《Glia》1994,12(3):219-227
The expression of sodium channel α-subunit isoforms in astrocytes in adult rat spinal cord and optic nerve was examined utilizing immunocytochemical methods with antibodies generated against conserved and subtype-specific sequences of the sodium channel. In adult rat spinal cord, astrocytes within the dorsal and ventral funiculi were immunolabelled with antibody SP20, which recognizes a conserved sequence within sodium channel types I, II, and III. In addition, astrocytes within these spinal cord white matter tracts were immunostained with antibody SP11-II, which recognizes sodium channel type II. Antibodies SP11-I and SP32-III, which are directed against subtype-specific sequences in sodium channel types I and III, respectively, did not label astrocytes in the dorsal and ventral funiculi of the spinal cord. In optic nerves, astrocytes were immunostained with antibody SP20. However, no detectable labelling of cells within the optic nerve was observed with antibodies SP11-I, SP11-II, and SP32-III. These observations demonstrate that sodium channel II is expressed by astrocytes in spinal cord white matter. Moreover, these data suggest that regional factors regulate the level of sodium channel isoform expression in astrocytes. 相似文献
105.
磷脂酶A2激活在鼠急性缺血性脑损伤中的作用机制 总被引:14,自引:2,他引:12
目的 探讨急性脑缺血后脑组织内磷脂酶A2(PLA2)激活及细胞内[Ca^2 ]i与脑损伤的关系,为预防和治疗急性缺血性脑损伤提供理论基础和新的思路。方法 将局灶性脑缺血模型大鼠分5组(假手术组、缺血30、60、90、120min组),测定脑组织PLA2活力、脑细胞[Ca^2 ]i、脑含水量及缺血120min组脑组织PLA2表达量的改变。结果 脑缺血120min脑组织PLA2活性、[Ca^2 ]i、脑含水量较假手术组明显升高,并与时间呈正相关,缺血120min后脑组织中出现sPLA2-ⅡAmRNA表达,且cPLA2-ⅣmRNA表达水平较假手术组明显增强。结论 磷脂酶A2激活参与了脑缺血后神经细胞内钙超载及脑损伤的整人病理过程。 相似文献
106.
107.
刺五加叶皂甙单体Sb对培养大鼠心肌细胞动作电位的影响 总被引:1,自引:0,他引:1
本研究中所用的刺五加叶皂甙单体Sb(50、200μg/mL),使培养的wistar大鼠心肌细胞动作电位的波幅、波宽、阈电位、最大舒张电位、超射、最大除极速度及复极(10%、50%、90%)水平的动作电位波宽一致减小。Ca2+80μg/mL能使之反转,Sb作用与尼莫地平作用相似。上述结果表明Sb具有钙通道阻滞作用。 相似文献
108.
用低蛋白饮食方法建立豚鼠胆色素结石模型,共设对照、致石、维生素C修复、丹参修复和对照修复等5组,规定时间内处死动物,用放射免疫、固相酶联免疫、生物化学等方法检测肝细胞内环—磷酸腺甙(cAMP)、环—磷酸鸟嘌呤(cGMP)、钙调素(CaM)、钙,三磷酸腺甙酶(Ca2+-ATPase)、磷酸化酶a等水平。致石组豚鼠肝脏细胞内cAMP和磷酸化酶a升高,而cGMP,CaM和Ca2+-ATPase下降,表明肝细胞钙稳态呈失调状态。维生素C和丹参可调整肝细胞的上述改变,说明维生素C和丹参具有维持肝细胞钙稳态的作用。 相似文献
109.
Recently, inhalation anesthetics have been reported to block BK channels in adrenal chromaffin cells. To determine if BK block was characteristic only of inhalation anesthetics or was also a property of other general anesthetics we examined the effects of ketamine, an intravenous general anesthetic which is structurally different than inhalation anesthetics. Cell-attached and excised patch single channel and standard whole cell recording techniques were used to examine the effect of racemic ketamine on the BK channel activity in GH3 cells. When solutions containing 150 mM KCl are used in both the pipette and bath, the BK channels are characterized as a voltage-dependent channel with a unit conductance of 150–300 pS. Racemic ketamine (at clinically relevant concentrations; 2–500 μM) selectively blocked BK channels in a dose-dependent, reversible manner as evidenced by decreases in NPo (number of channels × open probability). This decrease was due to both a decrease in mean open time and an increase in the mean closed time but without a decrease in single-channel current amplitude. Ketamine shifts the Po vs voltage curve to higher potentials without a change in the slope of the voltage dependence. Ketamine also shifts the Po vs [Ca+2] relationship to higher Ca+2 concentrations. The IC50 for the single-channel block by ketamine is 20.3 ± 15.9 μM. In an effort to confirm that the effect of ketamine was predominantly due to a block of the BK channels, standard whole cell techniques were utilized. As with the single-channel experiments, ketamine (2–500 μM) produced a dose-dependent, voltage-independent and reversible decrease in outward current with an IC50 of 23.7 ± 11.5 μM. Addition of 100 μM ketamine to cells pretreated with the BK channel blocker, charybdotoxin (ChTX), did not result in a further decrease in outward current. These results demonstrate a selective effect of ketamine at clinically relevant concentrations which is consistent with results reported for inhalation anesthetics. 相似文献
110.
We tested the hypothesis that electric perturbation influences 45Ca incorporation in extracellular matrix (ECM) of cartilage in vitro. Hypertrophic chondroblasts of tibial epiphyses (HC), sternum (SC), and skin fibroblasts (F) were cultured from chick embryos. HC, SC, and F cells were micromass seeded three times per week and maintained at 37.5 degrees C with 5% CO2 for two weeks. Cultures were randomly designated control (C) or exposed (E) to a pulsed electromagnetic field (PEMF). A time course experiment of calcium incorporation for all cultured groups showed that 24 h of exposure produced the largest biological response in chondroblasts. Calcium incorporation required supplemental phosphate. Autoradiography data indicated that the calcium incorporation into macromolecules largely occurred in the ECM. 45Ca steady-state perturbation was enhanced by Streptomyces hyaluronidase (SH) but not by testicular hyaluronidase (TH). 45Ca incorporation experiments tested the effects of phosphate, SH, TH, and PEMF alone and in various combinations on these cultures. Only PEMF or SH plus PEMF with phosphate enhanced 45Ca incorporation. Other experiments examined the effect of rotenone or freeze-thawing on cells exposed to PEMF. PEMF plus freeze-thaw enhanced calcium incorporation in HC only. PEMF appeared to cause disruption of the ECM, enhancing the probability of matrix calcification. 相似文献