共查询到20条相似文献,搜索用时 15 毫秒
1.
V. C. Kowtha H. J. Bryant V. Krauthamer K. H. Iwasa D. A. Stenger 《Cellular and molecular neurobiology》1996,16(1):1-9
Summary 1. We report that NG108-15 (neuroblastoma × glioma) cells differentiated in defined serum-free media are capable of exhibiting
stable automaticity (the spontaneous occurrence of regenerative action potentials) following exposure to extracellular perfusates
containing NH4Cl.
2. Membrane depolarization (4–5 mV) concomitant with an increased pHi during NH4Cl exposure are followed by hyperpolarization (5–7 mV), subthreshold oscillations, and spontaneous firing after the removal
of NH4Cl.
3. Cells cultured in 10% serum did not exhibit automaticity. Cells cultured in serum-free media are twice as likely to show
automaticity as those cultured in reduced (1.5%) serum media.
4. We have examined factors that contribute to the events following NH4Cl exposure, namely, membrane depolarization and hyperpolarization, subthreshold oscillations, and automaticity. The inward
currents activated at more negative potentials and the ionic currents associated with pronounced afterhyperpolarization in
NG108-15 cells cultured in serum-free media provide a basis for the repetitive activity in general and automaticity in particular. 相似文献
2.
Zhang Yu-an Takashi Imanishi Tetsuyuki Wada Seiji Ichida 《Neurochemical research》1999,24(8):1059-1066
The proportions of calcium (Ca2+) channel subtypes in chick or rat P2 fraction and NG 108-15 cells were investigated using selective L-, N-, P- and P/Q- type Ca2+ channel blockers. KCl-stimulated 45Ca2+ uptake by chick P2 fraction was blocked by 40~50% using N-type Ca2+ channel blockers [-conotoxin GVIA, aminoglycoside antibiotics and dynorphin A(1–13)], but was not inhibited by P- or P/Q-type blockers (-agatoxin IVA or -conotoxin MVIIC). On the other hand, KCl-stimulated 45Ca2+ uptake by rat P2 fraction was blocked by 30~40% using P- or P/Q-type Ca2+ channel blockers, but was not inhibited by N-type Ca2+ channel blockers. The L-type Ca2+ channel blockers 1,4-dihydropyridines, diltiazem and verapamil, but not calciseptine (CaS), inhibited both KCl-stimulated 45Ca2+ uptake and veratridine-induced 22Na+ uptake by chick or rat P2 fraction with similar IC50 values. CaS did not have any effect on 45Ca2+ uptake by either chick or rat P2 fraction. In NG108-15 cells, CaS, -agatoxin IVA and -conotoxin MVIIC, but not -conotoxin GVIA, inhibited KCl-stimulated 45Ca2+ uptake by 30–40%. Various combinations of these Ca2+ channel blockers had no significant additional effects in chick or rat P2 fraction or NG 108-15 cells. These findings suggest that KCl-stimulated 45Ca2+ uptake by chick or rat P2 fraction and NG 108-15 cells is a convenient and useful model for screening whether or not natural or synthetic substances have selective effects as L-, N-, P-, or P/Q- type Ca2+ channel antagonists or agonists. 相似文献
3.
Phospholipid base-exchange enzymes catalyze the incorporation of nitrogenous bases into phosphoglycerides by a calcium-dependent
mechanism. In this study, we describe the effect of ethanol on the incorporation of radioactive serine, choline and ethanolamine
into their respective phospholipids in a neuroblastoma x glioma hybrid cell line (NG 108-15). Long term ethanol exposure induced
a potentiation of the incorporation of [14C]serine into phosphatidylserine. Moreover, the phosphorus content of PS was found to be increased after long-term ethanol
exposure. No concomitant changes in the phosphorus content of other phospholipids were observed. The results indicate that
in NG 108-15 cells, the incorporation of radiolabelled serine into PS is potentiated during chronic ethanol exposure. 相似文献
4.
We previously reported that radicicol (Rad) and geldanamycin (Geld), heat shock protein 90 (Hsp90) inhibitors, potentiate neurite growth of cultured sensory neurons from chick embryo. We now show that the antibiotics induce neurite growth in NG108-15 cells. Treatment of the cells with these drugs caused transient decrease in protein levels of Raf1, ERK1/2, phosphorylated ERK1/2, Akt1, and CDK4. The neurite growth of NG108-15 induced by the inhibitors was blocked by actynomycin D, but the neurite growth stimulated by dbcAMP in the cells was not affected. The neurite growth could be due to a change in the synthesis of some specific protein(s) and is speculated to be due to the transient downregulation of particular-signaling molecules stabilized by Hsp90. 相似文献
5.
Shei-Ying Hu Shu-Ling Song Mei-Ying Ho Sheau-Huei Chueh 《Journal of neurochemistry》1997,68(2):846-854
Abstract: Prior treatment of NG108-15 cells with phosphatase inhibitors including okadaic acid and calyculin A inhibited the elevation of cytosolic Ca2+ concentration ([Ca2+ ]i ) induced by bradykinin by ∼63%. This inhibition was dependent on the concentration of okadaic acid with an IC50 of 0.15 n M . Okadaic acid treatment only lowered the maximal response of [Ca2+ ]i increase and had no effect on the EC50 value for bradykinin regardless of the presence of extracellular Ca2+ . Neither the capacity of 45 Ca2+ accumulation within intracellular nonmitochondrial Ca2+ stores nor the magnitude of [Ca2+ ]i increase induced by thapsigargin was reduced by the treatment of okadaic acid. In contrast, the same phosphatase inhibitor treatment inhibited the bradykinin-evoked inositol 1,4,5-trisphosphate (IP3 ) generation, the Mn2+ influx, and the capacity of mitochondrial Ca2+ accumulation. Furthermore, the sensitivity of IP3 in the Ca2+ release was suppressed by okadaic acid pretreatment. Our results suggest that the reduction of bradykinin-induced [Ca2+ ]i rise by the promotion of protein phosphorylation was attributed to the reduced activity of phospholipase C, the decreased sensitivity to IP3 , and the slowed rate of Ca2+ influx. Thus, phosphorylation plays a role in bradykinin-sensitive Ca2+ signaling cascade in NG108-15 cells. 相似文献
6.
Song T Hatano N Kume K Sugimoto K Yamaguchi F Tokuda M Watanabe Y 《FEBS letters》2005,579(25):5658-5662
We demonstrate that neuronal nitric-oxide synthase (nNOS) is directly inhibited through the phosphorylation of Thr(1296) in NG108-15 neuronal cells. Treatment of NG108-15 cells expressing nNOS with calyculin A, an inhibitor of protein phosphatase 1 and 2A, revealed a dose-dependent inhibition of nNOS enzyme activity with concomitant phosphorylation of Thr(1296) residue. Cells expressing a phosphorylation-deficient mutant in which Thr(1296) was changed to Ala proved resistant to phosphorylation and suppression of NOS activity. Mimicking phosphorylation mutant of nNOS in which Thr(1296) is changed to Asp showed a significant decrease in nNOS enzyme activity, being competitive with NADPH, relative to the wild-type enzyme. These data suggest that phosphorylation of nNOS at Thr(1296) may involve the attenuation of nitric oxide production in neuronal cells through the decrease of NADPH-binding to the enzyme. 相似文献
7.
We have reported that the delta3 isoform of Ca2+/ calmodulin-dependent protein kinase II (CaM kinase II) is abundant in the nucleus in cerebellar granule cells. To examine the possibility that the nuclear isoforms of CaM kinase II are involved in the expression of brain-derived neurotrophic factor (BDNF), we transiently overexpressed the delta3 isoform in NG108-15 cells. The quantitative RT-PCR analysis revealed that rat cerebellum and NG108-15 cells expressed the exon IV-containing mRNA of BDNF (exon IV-BDNF mRNA) more than the exon III-BDNF mRNA. Treatment of NG108-15 cells with Bay K 8644 increased both exon III- and exon IV-BDNF mRNAs, and overexpression of the 83 isoform potentiated the expression of the exon IV-BDNF mRNA. The potentiation was not observed in the cells that were overexpressed with either the 61 isoform, a nonnuclear isoform, or the inactive mutant of the delta3 isoform. We constructed the luciferase reporter gene following the promoter upstream of exon IV and confirmed that overexpression of the delta3 isoform increased luciferase gene expression. Double-immunostaining of NG108-15 cells with the antibodies to CaM kinase II and BDNF clearly showed that BDNF was highly expressed in the cells that were overexpressed with the delta3 isoform or the alphaB isoform, another nuclear isoform of CaM kinase II. These results suggest that the nuclear isoforms of CaM kinase II are involved in the expression of BDNF. 相似文献
8.
Bradykinin (BK) excites dorsal root ganglion cells, leading to the sensation of pain. The actions of BK are thought to be mediated by heterotrimeric G protein-regulated pathways. Indeed there is strong evidence that in different cell types BK is involved in phosphoinositide breakdown following activation of Gq/11. In the present study we show that the Ca2+ current flowing through L-type voltage-gated Ca2+ channels in NG108-15 cells (differentiated in vitro to acquire a neuronal phenotype), measured using the whole-cell patch clamp configuration, is reversibly inhibited by BK in a voltage-independent fashion, suggesting a cascade process where a second messenger system is involved. This inhibitory action of BK is mimicked by the application of 1,2-oleoyl-acetyl glycerol (OAG), an analog of diacylglycerol that activates PKC. Interestingly, OAG occluded the effects of BK and both effects were blocked by selective PKC inhibitors. The down modulation of single L-type Ca2+ channels by BK and OAG was also investigated in cell-attached patches. Our results indicate that the inhibitory action of BK involves activation of PKC and mainly shows up in a significant reduction of the probability of channel opening, caused by an increase and clustering of null sweeps in response to BK. 相似文献
9.
三种蜘蛛粗毒对NG108—15细胞电压门控钠通道的抑制作用 总被引:4,自引:0,他引:4
利用小鼠神经细胞瘤×大鼠神经胶质细胞的杂交细胞NG108-15,通过全细胞记录(whole-cellrecording)模式的膜片钳技术,检验了虎纹捕鸟蛛(Selenocosmia
huwena)、海南捕鸟蛛(Selenocosmia hainana)和广西大疣蛛(Macrothele guangxiasp)的粗毒对NG108-15细胞膜上电压门控TTX敏感型钠电流和延迟整流钾电流的作用.结果表明,三种蜘蛛粗毒对外向延迟整流钾电流没有明显作用,但对TTX敏感型的快钠电流表现出较强的抑制效应.抑制效应呈量效关系.三种粗毒抑制钠电流的EC 相似文献
10.
Takashi Imanishi Kayoko Matsushima Akinori Kawaguchi Hajime Asano Yoshinori Funakami Tetsuyuki Wada Takashi Masuko Shigeru Yoshida Seiji Ichida 《Neurochemical research》2009,34(5):1011-1019
Characteristics for the up-regulated response in the concentration of intracellular calcium ion ([Ca2+]
i
) and in the sodium ion (Na+) current by serotonin (5-HT) were investigated in differentiated neuroblastoma × glioma hybrid NG108-15 (NG) cells. The results
for the changes in [Ca2+]
i
by 5-HT were as follows, (1) The 5-HT-induced Ca2+ response was inhibited by 3 × 10−9 M tropisetron (a 5-HT3 receptor blocker), but not by other types of 5-HT receptor blockers; (2) The 5-HT-induced Ca2+ response was mainly inhibited by calciseptine (a L-type Ca2+ blocker), but not by other types of Ca2+ channel blockers or 10−7 M TTX (a voltage-sensitive Na+ channel blocker); (3) When the extracellular Na+ was removed by exchange with choline chloride or N-methyl-d-glucamine, the 5-HT-induced Ca2+ response was extremely inhibited. The results for the 5-HT-induced Na+ current by the whole cell patch-clamp technique were as follows, (1) The 5-HT-induced Na+ current in differentiated cells was significantly larger than that in undifferentiated cells; (2) The ED50 value for 5-HT-induced Na+ current in undifferentiated and differentiated cells was almost the same, about 4 × 10−6 M each other; (3) The 5-HT-induced Na+ current was completely blocked by 3 × 10−9 M tropisetron, but not by other 5-HT receptor antagonists and 10−7 M TTX. These results suggested that 5-HT-induced Ca2+ response in differentiated NG cells was mainly due to L-type voltage-gated Ca2+ channels allowing extracellular Na+ to enter via 5-HT3 receptors, but not through voltage-gated Na+ channels. 相似文献
11.
Jeffrey J. Yourick Patricia A. Eklo Michael P. McCluskey Radharaman Ray 《Cell biology and toxicology》1991,7(3):229-237
Acetylcholinesterase (AChE) in the clonal NG108-15 cell line has been previously characterized. This cell line represents an in vitro system to study AChE regulation and effects of chemical compounds that may alter AChE activity. Recently, glycyl-L-glutamine (GLG) was demonstrated to function as a neurotrophic factor for maintenance of AChE content in cat denervated superior cervical ganglion cells. In the present study, regeneration of AChE activity in cultures of undifferentiated NG108-15 cells after soman inhibition was investigated in the presence and absence of GLG. Cells were treated with soman (5.5 × 10–6 M) for 15 min and then washed to remove excess soman. Culture medium containing either GLG (10–6, 10–5, or 10–4M) or glycyl-L-glutamic acid (10–6 M) was added to cultures after soman treatment and remained in the medium until cell harvest. Cells were physically detached at various times after soman treatment and specific AChE activity was determined. After soman, AChE activity dramatically decreased to less than 1% of untreated cellular activity at 1 hr. AChE activity gradully increased after 5 hr, while untreated cell AChE activity was regained 20 hr after soman. The t1/2 for AChE regeneration was approximately 10 hr. GLG did not increase the rate of AChE regeneration after soman inhibition. These results indicate that GLG is not a directly acting neurotrophic factor for AChE synthesis in NG108-15 cells after chemical AChE inactivation.Abbreviations AChE
acetylcholinesterase
- NG108-15 cell
neuroblastoma-glioma 108-15 cell
- DMEM
Dulbecco's modified Eagles minimal essential medium
- FBS
fetal bovine serum
- GLGA
glycyl-L-glutamic acid
- L-GA
L-glutamic acid
- GLG
glycyl-L-glutamine
- GD
soman
The opinions or assertions contained herein are the private views of the authors and are not to be construed as reflecting the view of the Department of the Army or the Department of the Army or the Department of Defense. 相似文献
12.
Abstract: Previous studies have shown that in the neuroblastoma X glioma hybrid cell line NG108-15 lithium is able to induce an increase in diacylglycerol levels. This effect was shown to be enhanced by the presence of bradykinin. Another striking effect of lithium was a marked gain in the level of the liponucleotide phosphatidyl-CMP. Increased phosphatidyl-CMP levels were detected in the presence of lithium alone but were considerably more pronounced in the presence of both lithium and bradykinin. These results are consistent with the inhibitory action of lithium on key enzymes of the degradation pathway of inositol phosphates, resulting in a decrease in cellular inositol content and in an elevation in levels of phosphorylated inositols. Comparison of the mass of the inositol phosphates and diacylglycerol showed that the lithium-induced diacylglycerol levels were substantially greater than would be expected from phosphoinositide hydrolysis alone. One possible reason for the increase in the level of diacylglycerol through the action of lithium is the reversal of the reaction for the formation of phosphatidyl-CMP. The resulting phosphatidic acid would then need to be further dephosphorylated to diacylglycerol. The lithium-induced elevation of phosphatidyl-CMP was prevented by addition of myo -inositol (10–30 m M ), suggesting that the increase in liponucleotide level was due to depletion of cellular inositol. Under the same conditions the elevated diacylglycerol concentration remained unchanged. Consequently, phosphatidyl-CMP is not its source, and diacylglycerol may arise through an effect of lithium on the degradation of phospholipids other than phosphoinositides. The action of phospholipase C or D on phosphatidylcholine is the most likely mechanism. 相似文献
13.
Imanishi T Matsushima K Kawaguchi A Wada T Yoshida S Ichida S 《Neurochemical research》2006,31(1):33-40
Characteristics of the increasing effect for the concentration of intracellular calcium ions ([Ca2+]i) by high-KCl application were investigated in the neuroblastoma×glioma hybrid NG108-15 cell line (NG108-15 cells). The present
study confirmed that the increasing effect of [Ca2+]i by high-KCl application in single NG108-15 cells, differentiated with dibutyryl cAMP (Bt2cAMP), was significantly enhanced, compared to undifferentiated cells. The following observations were made at first: (1)
The response to high-KCl application, in both undifferentiated and differentiated cells, was significantly inhibited by calciseptine
(CaS), an L-type Ca2+ channel blocker, but not by N-, P- and R-type Ca2+ channel blockers. The IC50 values for CaS in both undifferentiated and differentiated cell was almost identical. (2) The inhibitory effect of CaS was
irreversible. (3) The increasing effect for [Ca2+]i by high-KCl application was completely dependent on the presence of extracellular calcium ions. (4) The increased [Ca2+]i by high-KCl application under a plateau concentration was quickly decreased to basal levels when the high-KCl solution was
exchanged for a high-KCl solution containing EGTA (without CaCl2). Together, these results suggest that the enhancement of the response effect of [Ca2+]i by high-KCl application in differentiated single NG108-15 cells was mainly due to the quantitative increase of L-type voltage-sensitive
calcium channels (VSCCs), which were irreversibly inhibited by CaS. 相似文献
14.
The dopamine D2 receptor (D2R) is target for antipsychotic drugs and associated with several neuropsychiatric disorders. D2R has a long third cytoplasmic loop and a short carboxyl-terminal cytoplasmic tail. It exists as two alternatively spliced isoforms, termed D2LR and D2SR, which differ in the presence and absence, respectively, of a 29 amino acid insert in the third cytoplasmic loop. To evaluate the differential roles of the two D2R isoforms, we transfected both isoforms into NG108-15 cells and observed their subcellular localization by a confocal laser scanning light microscope. D2SR was predominantly localized at the plasma membrane, whereas D2LR was mostly retained in the perinuclear region around the Golgi apparatus. Using a yeast two hybrid system with a mouse brain cDNA library and coimmunoprecipitation assay, we found that heart-type fatty acid binding protein (H-FABP) interacts with D2LR but not with D2SR. H-FABP is a cytosolic protein involved in binding and transport of fatty acids. Overexpressed H-FABP and endogenous H-FABP were colocalized with the intracellular D2LR in NG108-15 cells. Furthermore, in the rat striatum, H-FABP was detected in the D2R-expressing neurons. From these results, H-FABP is associated with D2LR, and may thereby modulate the subcellular localization and function of D2LR. 相似文献
15.
Keita Nagasawa Takeshi Tarui Shigeru Yoshida† Fumiko Sekiguchi Maho Matsunami Ai Ohi Kazuki Fukami Seiji Ichida‡ Hiroyuki Nishikawa§ Atsufumi Kawabata 《Journal of neurochemistry》2009,108(3):676-684
We investigated if stimulation of T-type Ca2+ channels with sodium hydrosulfide (NaHS), a donor of hydrogen sulfide (H2 S), could cause neuronal differentiation of NG108-15 cells. Like dibutyryl cyclic AMP (db-cAMP), treatment with NaHS at 1.5–13.5 mM for 16 h enhanced neurite outgrowth in a concentration-dependent manner. Synergistic neuritogenic effect was obtained in the cells stimulated with NaHS in combination with db-cAMP at subeffective concentrations. Exposure to NaHS or db-cAMP for 2 days resulted in enhancement of expression of high-voltage-activated currents consisting of N-, P/Q-, L- and also other types, but not of T-type currents. Mibefradil, a pan-T-type channel blocker, abolished the neuritogenesis induced by NaHS, but not by db-cAMP. The NaHS-evoked neuritogenesis was also completely blocked by pretreatment with BAPTA/AM, a chelator of intracellular Ca2+ , and by zinc chloride at a concentration known to selectively inhibit Cav 3.2 isoform of T-type Ca2+ channels, but not Cav 3.1 or Cav 3.3. Further, l -ascorbate, recently proven to selectively inhibit Cav 3.2, abolished the neuritogenic effect of NaHS, but not db-cAMP. Our data thus demonstrate that NaHS/H2 S is a novel inducer of neuronal differentiation in NG108-15 cells, as characterized by neuritogenesis and expression of high-voltage-activated currents, and suggest the involvement of T-type Ca2+ channels, especially Cav 3.2. 相似文献
16.
Extracellular metabolism of nucleotides in neuroblastoma x glioma NG108-15 cells determined by capillary electrophoresis 总被引:2,自引:0,他引:2
1. The metabolism of extracellular nucleotides in NG108-15 cells, a neuroblastoma × glioma hybrid cell line, was studied by means of capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC).2. In NG108-15 cells ATP, ADP, AMP, UTP, UDP, and UMP were hydrolyzed to the nucleosides adenosine and uridine indicating the presence of ecto-nucleotidases and ecto-phosphatases. The hydrolysis of the purine nucleotides ATP and ADP was significantly faster than the hydrolysis of the pyrimidine nucleotides UTP and UDP.3. ATP and UTP breakdown appeared to be mainly due to an ecto-nucleotide- diphosphohydrolase. ADP, but not UDP, was initially also phosphorylated to some extent to the corresponding triphosphate, indicating the presence of an adenylate kinase on NG108-15 cells. The alkaline phosphatase (ALP) inhibitor levamisole did not only inhibit the hydrolysis of AMP to adenosine and of UMP to uridine, but also the degradation of ADP and to a larger extent that of UDP. ATP and UTP degradation was only slightly inhibited by levamisole.4. These results underscore the important role of ecto-alkaline phosphatase in the metabolism of adenine as well as uracil nucleotides in NG108-15 cells. Dipyridamole, a potent inhibitor of nucleotide breakdown in superior cervical ganglion cells, had no effect on nucleotide degradation in NG108-15 cells.5. Dipyridamole, which is a therapeutically used nucleoside reuptake inhibitor in humans, reduced the extracellular adenosine accumulation possibly by allosteric enhancement of adenosine reuptake into the cells. 相似文献
17.
Louise Luckenbill-Edds 《Cell and tissue research》1990,260(3):485-493
Summary Adhesion of the neuronal cell surface to its underlying substrate plays an important role in neurite outgrowth in vitro. I have investigated the adhesive basis for neurite outgrowth in the presence of cytochalasin D, a disruptor of actin-containing microfilaments, and in the presence of vinblastine, a depolymerizer of microtubules. Scanning electron microscopy shows that cytochalasin D does not alter the branching configuration of filopodia on a laminin substrate, although processes are shorter and tapered distally in the presence of the drug. Using a standard attachment assay for the neuroblastoma x glioma cell line (NG108-15) I show that vinblastine does not influence attachment of NG108-15 cells to either plastic or laminin. Cytochalasin D-treated cells normally attach to high concentrations of a laminin substrate (20 g/ml). However, when cell are seeded on a laminin substrate at lower concentrations (0.001–10 g/ml), or on YIGSR, a fragment of laminin, cytochalasin D increases cell attachment. Cytochalasin D increases attachment in a dose-dependent manner when cells are seeded on plain polystyrene plastic, so that the number of cells attached to plastic in 1 M cytochalasin D is similar to the number attached to laminin (20 g/ml). Combining low concentrations of cytochalasin D and laminin results in greater attachment than with either agent alone. Mild trypsinization of the cell surface reduces the CD-enhanced attachment to plastic, indicating that a protein on the cell surface may be involved. The effect of cytochalasin D appears to be cell specific since cytochalasin D does not affect the attachment of a fibroblast cell line (NIH 3T3) to laminin and plastic. I hypothesize that a molecular mechanism is involved in which cytochalasin D promotes attachment by interacting with the cell surface via the actin microfilament system. 相似文献
18.
19.
Doebler JA 《Neurochemical research》2000,25(2):263-268
Studies were conducted to determine the effects of bath application of the protonophores carbonyl cyanide m-chlorophenylhydrazone (CCCP) and carbonyl cyanide p-(trifluoromethoxy)-phenylhydrazone (FCCP) on membrane electrical characteristics of differentiated NG108-15 (neuroblastoma X glioma hybrid) cells. Membrane resting potential (Vm), input resistance (Rin) and electrically induced action potential generation were measured using intracellular micro-electrode techniques. Both compounds produced concentration-dependent depolarization rather than the hyperpolarization commonly found with other central mammalian neurons. CCCP and FCCP also reduced Rin and disrupted the generation of action potentials in a concentration-dependent manner. The contribution of the observed alterations to the in vivo toxicity of these compounds remains to be established. 相似文献
20.
Doebler JA 《Cell biology and toxicology》1999,15(5):279-289
Studies were conducted using a novel in vitro approach to investigate the efficacy of acetamidine hydrochloride (ACE) and guanidine hydrochloride (GUAN), previously shown to block gramicidin D (GRAM) channels in artificial membranes, in preventing the toxic effects of GRAM in NG108-15 (neuroblastoma×glioma hybrid) cells. Specifically, intracellular microelectrode techniques were employed to examine changes in membrane resting potential (V
m) and input resistance (R
in). At 1 mol/L, ACE significantly reduced loss of V
m induced by 1 or 10 g/ml GRAM, although higher concentrations of ACE did not afford enhanced antagonism. GUAN, in contrast, produced a concentration-dependent antagonism of GRAM-induced V
m and R
in loss, with high concentrations (10 or 100 mol/L) completely preventing diminutions in both V
m and R
in. In control cells superfused without GRAM, ACE produced a direct, concentration-dependent reduction in V
m and R
in, whereas GUAN hyperpolarized NG108-15 cells but did not alter R
in. These data represent the initial demonstration of the reversal of GRAM toxicity in an intact cell system. 相似文献