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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The intracellular free Ca2+ concentration, [Ca2+]i, plays an important role in regulating neurite growth in cultured neurons. Insofar as [Ca2+]i is partly a function of Ca2+ influx through voltage-sensitive calcium channels (VSCC), Ca2+ entry through VSCC should influence neurite growth. Vertebrate neurons may possess several types of VSCC. The most frequently described VSCC types are usually designated L, T and N. In most preparations, these VSCC types respond differently to certain pharmacological agents, including Cd2+, Ni2+, the dihydropyridines nifedipine and BAY K8644, and the aminoglycoside antibiotics. We used these agents to study the role of Ca2+ influx in regulating neurite initiation and length in cultures of chick embryo brain neurons and N1E-115 mouse neuroblastoma cells. In chick neurons, nifedipine and Cd2+ (less than 50 microM), which have been reported to inhibit L-type channels, reduced neurite initiation, but not mean neurite length. Ni2+ (less than 100 microM), reported to inhibit T-type channels, had no effect on either initiation or length. Low concentrations of most aminoglycosides (less than 300 microM), reported to inhibit N-type channels, had no effect on neurite initiation, but high concentrations of streptomycin (great than 300 microM), reported to inhibit both L- and N-type channels, reduced neurite initiation. BAY K8644, which enhances current flow through L-type channels, had no effect except at high concentration (50 microM), which inhibited initiation. N1E-115 neuroblastoma cells have been reported to contain L-type and T-type channels, but thus far no channel similar to the N-type has been described. In cultured N1E-115 cells, nifedipine (5 microM), Cd2+ (5 microM), and streptomycin (200 microM) reduced neurite initiation, while nickel (50 microM) and neomycin (100 microM) did not affect initiation. None of these agents altered neurite length. In N1E-115 cells, whole-cell voltage clamp recordings showed that nifedipine and Cd2+ inhibited L-type channels but not T-type channels, while Ni2+ inhibited T-type channels but not L-type channels. Streptomycin slightly inhibited L-type channels but enhanced current flow through T-type channels. Neomycin slightly inhibited both channel types. These data indicated that neurite initiation in these two cell types may be modulated by Ca2+ influx through L-type channels, but not T- or N-type channels. Neurite length was not significantly influenced by any of the agents tested, suggesting that Ca2+ influx through VSCC may not affect neurite elongation.
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PMID:L-type calcium channels may regulate neurite initiation in cultured chick embryo brain neurons and N1E-115 neuroblastoma cells. 169 74

1. The effect of micromolar concentrations of divalent metal cations on ion current activated by 5-hydroxytryptamine (5-HT) was investigated in NCB-20 neuroblastoma cells by the use of the whole-cell, patch-clamp technique. 2. Ion current activated by 5-HT in these cells was mimicked by 5-HT3 receptor agonists, blocked by nanomolar concentrations of selective 5-HT3 receptor antagonists and reversed polarity at approximately 0 mV. These properties indicate that this current is carried primarily if not exclusively by the nonspecific cation channel activated by the 5-HT3 receptor. 3. The Group IIb metal cations Cd2+ and Zn2+ and the Group Ib cation Cu2+ inhibited 5-HT-activated current with inhibition increasing in a concentration-dependent manner over micromolar concentrations of the ions. The order of potency of the ions for inhibiting 5-HT-activated current was Zn2+ (IC50 = 20 microM) greater than or equal to Cu2+ (IC50 = 25 microM) greater than Cd2+ (IC50 = 75 microM) at -50 mV. The other divalent metal cations tested (Ba2+, Co2+, Mg2+, Mn2+, and Ni2+) produced little or no inhibition of 5-HT-activated current at concentrations up to 200 microM. 4. Inhibition of 5-HT-activated current by Cd2+ and Zn2+ was dependent on membrane potential with the Kd increasing e-fold per 72 and 52 mV, respectively. Inhibition by Cu2+ was much less voltage dependent with the Kd increasing e-fold per 233 mV. 5. Inhibition by all three cations decreased with increasing concentration of agonist over a range of 5-HT concentrations from 1 to 10 microM.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibition of 5-HT3 receptor-mediated ion current by divalent metal cations in NCB-20 neuroblastoma cells. 172 46

The effect of calcium channel antagonists on depolarization and carbachol evoked release of [3H]noradrenaline in the human neuroblastoma, SH-SY5Y, was investigated. Nifedipine, verapamil and diltiazem completely inhibited the depolarization evoked release of [3H]noradrenaline with IC50 values of 0.44 +/- 0.1 microM, 3.6 +/- 0.24 microM and 5.6 +/- 0.2 microM respectively. In addition, nickel, cobalt and cadmium, all at 2 mM, inhibited depolarization evoked release by 89.2 +/- 2.3%, 72.6 +/- 1.6% and 102.5 +/- 1.4% respectively. Furthermore, omega-conotoxin resulted in at least 20% inhibition of potassium evoked release, suggesting a role of N-type calcium channels. Carbachol evoked release of [3H]noradrenaline was inhibited by 10(-4) M nifedipine, diltiazem and verapamil by 15.6 +/- 1.1%, 14.6 +/- 3.2% and 23.6 +/- 1.8% respectively and by 2 mM nickel, cobalt and cadmium by 13.8 +/- 3.2%, 34 +/- 2.1% and 6.5 +/- 3.7% respectively. These results suggest that depolarization evoked release of [3H]noradrenaline is mediated via L- and N-type calcium channels, whereas, carbachol evoked release does not appear to be coupled an L-, T- or N-type voltage sensitive calcium channel.
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PMID:The effect of calcium channel antagonists on the release of [3H]noradrenaline in the human neuroblastoma, SH-SY5Y. 174 5

Since cadmium exposure results in neuropathological alterations in central nervous system, we investigated the effects of cadmium on the gene expression of neuroblastoma (GOTO) cells. We observed an increase in mRNA levels of heat-shock protein (hsp) 70, hsp 90, hsp 32 and metallothionein after treatment of GOTO cells with cadmium, although the time courses of the changes of individual mRNA of the heat-shock proteins and metallothionein were somewhat different from each other. An accumulation of N-myc and multidrug-resistance gene (MDR1) mRNA was detected in the presence of cadmium. This is contrary to the previous report, in which an inverse correlation between the expression of MDR1 gene and N-myc oncogene in human neuroblastoma had been described. However, the increase of N-myc and MDR1 mRNA in the present study is not likely due to the loss of regulatory mechanism of these genes by cytotoxic effects of cadmium, because active protective mechanisms such as heat-shock proteins and metallothionein could be induced under these conditions.
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PMID:Cadmium causes increases of N-myc and multidrug-resistance gene mRNA in neuroblastoma cells. 175 38

The conditions were evolved and checked for simultaneous determination of cadmium and lead levels in plant material using the flame technique of ASA. For decomposition of the organic substances in plant material wet mineralization was used with a mixture of nitric acid, perchloric acid and sulpuric acid in volume proportions 6:2:0.25. The levels of cadmium and lead were determined in the organic phase after extraction with n-butyl acetate of the previously produced complexes with NaDDTK. The obtained limits of cadmium and lead detectability were 0.002 and 0.02 mg/kg respectively. The recovery rate of the method ranged from 96 to 98%, while the variability index was from 2.6 to 10.2%. The correctness of the evolved analytical procedure was confirmed by determination of the content of both elements in the NBS-SRM 1571 standard (orchard leaves) and by participation in the international interlaboratory investigation of the Polish standard (dried cabbage leaves).
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PMID:[A method of atomic absorption spectrophotometry (AAS) for analysis of cadmium and lead levels in the plant material]. 210 Nov 73

1. Currents through voltage-activated Ca2+ channels in rat dorsal root ganglion (DRG) x mouse neuroblastoma hybrid (F-11) cells were studied using the whole-cell patch clamp technique with 30 mM-Ba2+ as charge carrier. Two components of the inward Ba2+ current were distinguished on the basis of voltage dependence and time course. Each component could be further subdivided based on pharmacology. 2. A transient inward current activated at test potentials positive to -40 mV, peaked within 20 ms and then decayed during a 200 ms depolarization. The peak amplitude of the transient current occurred between -10 and +10 mV. With a 300 ms conditioning pulse, half-inactivation of the transient current occurred at -30 mV. A sustained inward current activated at test potentials positive to -30 mV and reached a maximum at +20 to +30 mV. The sustained current showed little voltage-dependent inactivation over 200 ms. The amplitudes of both the transient and sustained currents were increased by perfusing with Ba2+ instead of Ca2+. 3. Most F-11 cells had both the transient and sustained Ba2+ currents although the relative amount of the two currents varied with culture conditions. The transient current was more prominent in cells fed with a 'growth' medium (15-20% serum) whereas the sustained current was increased in cells fed with a 'differentiation' medium (1% serum plus growth factors). F-11 cells can be used to study transient current in relative isolation from sustained Ca2+ current under certain culture conditions. The neuroblastoma parent of the F-11 cell line, N18TG-2 cells, exhibited little or no voltage-dependent Ba2+ current. 4. Brief application of omega-conotoxin fraction GVIA (10 microM) produced a long-lasting block of 81% of the sustained current and 27% of the transient current. 5. The transient and sustained Ba2+ currents in F-11 cells were reversibly blocked by brief exposure to Cd2+ or Ni2+. Block of the sustained current was evident with 100 nM-Cd2+ whereas the threshold concentration for Ni2+ block was 1 microM. Cd2+ and Ni2+ were equipotent blockers of the transient current. Dose-response curves for Cd2+ and Ni2+ block of both sustained and transient currents had shallow slopes suggesting that the block was more complex than a simple bimolecular interaction between blocker and one blocking site. Dose-response curves were fitted by a model that included two binding sites for each divalent blocker.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Multiple components of both transient and sustained barium currents in a rat dorsal root ganglion cell line. 215 39

Outward currents were recorded from voltage-clamped NG108-15 mouse neuroblastoma X rat glioma hybrid cells, differentiated with prostaglandin E1. Depolarising voltage steps from -70 mV, evoked a transient outward current from a threshold of -30 mV. The outward current showed complete inactivation at potentials positive to -10 mV. Inactivation was removed by hyperpolarisation with half-inactivation at -53 mV. The time course of the inactivation could be best fitted by two exponentials with mean time constants of 280 ms and 1.6 s at +80 mV. Tail current measurements showed a shift in the reversal potential with changes in external K+ concentration, consistent with K+ as the current-carrying ion. The outward current amplitude was reversibly reduced by 4-aminopyridine, and the time course of inactivation modified. In the presence of other K+ channel blockers (tetraethylammonium, barium and tetrahydroaminoacridine) the amplitude of the outward current was also reversibly reduced, but with a negligible effect on its time course. The current was unaffected by dendrotoxin, d-tubocurarine, apamin, Cd2+ and Ni2+, and by replacing external Ca2+ with Co2+ or Mg2+. In current clamp, action potential duration was greatly increased by 4-aminopyridine. The findings show that the NG108-15 cell line displays a transient outward current that resembles IK(A) but with a higher than usual threshold and relatively slow inactivation, and that this current is likely to be important for action potential repolarisation.
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PMID:A transient outward current in NG108-15 neuroblastoma x glioma hybrid cells. 235 30

1. Two types of voltage-sensitive calcium channels were identified and studied in the neuroblastoma cell line N1E-115. Calcium channel currents as carried by Ba2+ (50 mM) were recorded using the whole-cell variation of the patch-electrode voltage-clamp technique. 2. A transient (type I) inward Ba2+ current was evoked by a step depolarization from a holding potential of -80 mV to potentials more positive than -50 mV. The current amplitude became maximum around -20 mV. 3. A depolarization to potentials more positive than -20 mV evoked a long-lasting (type II) component of the inward Ba2+ current. This component reached its maximum around +10 mV and did not inactivate during a prolonged depolarizing pulse lasting 400 ms. 4. When preceded by a 5 s conditioning pulse to -30 mV, step depolarization failed to evoke a transient current due to inactivation. However, it induced a long-lasting current. 5. A transient current isolated as the component sensitive to conditioning depolarization became faster in its time course and smaller in its amplitude with membrane depolarization. The current direction was still inward at +60 mV. 6. From the differential voltage sensitivity and the independent channel activity described above, calcium channels responsible for the transient current (type I channel) and those responsible for the long-lasting current (type II channel) were considered to be two different entities. 7. Cd2+ preferentially blocked type II channels, whereas La3+ was a highly potent blocker for both types of calcium channels. 8. The relative potency for block by polyvalent cations was as follows (apparent dissociation constant in microM): La3+, 1.5 much greater than Ni2+, 47 greater than Cd2+, 160 = Co2+, 160 for type I channels, and La3+, 0.9 greater than Cd2+, 7.0 much greater than Ni2+, 280 greater than Co2+, 560 for type II channels. 9. The two types of calcium channels were equally sensitive to the temperature. The current amplitude was reduced by cooling below 30 degrees C. The temperature coefficient (Q10) value was estimated to be 3.0 between 20 and 30 degrees C, and 15.0 below 20 degrees C. Above 30 degrees C, warming reduced the amplitude slightly. 10. External application of dibutyryl adenosine 3',5'-phosphate (dibutyryl cyclic AMP) (1 mM) caused an increase in the amplitude of the type II current by 30-50%, while failing to enhance the type I component.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of two types of calcium channels in mouse neuroblastoma cells. 244 46

1. Maitotoxin (MTX) was an extraordinarily potent stimulant of phosphoinositide breakdown in the neuroblastoma hybrid NCB-20 cells. 2. Maximal responses were obtained at 0.25-0.5 ng MTX/ml, and resulted in increased formation of [3H]inositol mono-, bis-, and trisphosphates. Increased formation of [3H]inositol bis- and trisphosphate was observed as early as 15 sec after the addition of MTX. 3. MTX-induced phosphoinositide breakdown in NCB-20 cells was not antagonized by organic (nifedipine, methoxyverapamil) or inorganic (Mn2+, Co2+, Cd2+) calcium channel blockers. However, the response on phosphoinositide breakdown was completely eliminated in the absence of extracellular calcium. 4. The results suggest that MTX either directly stimulates phosphoinositide breakdown in a calcium-dependent manner or acts indirectly through calcium channels insensitive to organic/inorganic calcium channel blockers.
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PMID:Maitotoxin stimulates phosphoinositide breakdown in neuroblastoma hybrid NCB-20 cells. 244 66

1. Membrane currents were recorded from voltage-clamped, microelectrode-impaled cells of the NG108-15 mouse neuroblastoma x rat glioma clonal cell line, differentiated with prostaglandin E1. 2. A slow outward tail current reversing at post-pulse potentials between -80 and -90 mV was evoked by depolarizing pre-pulses to near 0 mV. The tail current was inhibited by Cd2+ ions (0.2-1 mM) and hence attributed to activation of a Ca2+-dependent K+ current by a priming voltage-activated Ca2+ current. 3. Two components to this tail current could be distinguished pharmacologically: an early (less than or equal to 50 ms) component inhibited by 1-5 mM-tetraethylammonium (TEA), and a late component lasting several hundred milliseconds inhibited by apamin (0.1-0.4 microM) or d-tubocurarine (0.1-0.5 mM). 4. Ionophoretic injection of Ca2+ ions evoked a transient outward current with an apparent reversal potential (from ramped current-voltage curves) of -70 mV. This current was succeeded or sometimes replaced by an inward current with an apparent reversal potential between -20 and -10 mV. 5. The outward current induced by Ca2+ injections was unaffected or partly inhibited by TEA (1-5 mM), but was strongly inhibited by apamin or d-tubocurarine. 6. Hyperpolarizing voltage steps from between -30 and -40 mV induced inward current relaxations reversing at between -80 and -90 mV. These were considered to result from deactivation of the voltage-dependent sustained K+ current, IM. 7. Application of methacholine, muscarine or Ba2+ ions produced an inward current, reduced input conductance and reduced IM deactivation relaxations. 8. It is concluded that differentiated NG108-15 cells possess several of the K+ currents present in sympathetic neurones, including a delayed rectifier current, two species of Ca2+-activated K+ current and the M-current.
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PMID:Voltage- and calcium-activated potassium currents in mouse neuroblastoma x rat glioma hybrid cells. 245 95


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