Calcium Currents in Retrogradely Labeled Pyramidal Cells From Rat Sensorimotor Cortex

2000 ◽  
Vol 83 (4) ◽  
pp. 2349-2354 ◽  
Author(s):  
Ansalan Stewart ◽  
Robert C. Foehring
Keyword(s):  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Cell Types ◽  
Calcium Currents ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Multiple Populations ◽  
Whole Cell Patch Clamp ◽  
The Mean ◽  
P Type

Our previous studies of calcium (Ca2+) currents in cortical pyramidal cells revealed that the percentage contribution of each Ca2+ current type to the whole cell Ca2+ current varies from cell to cell. The extent to which these currents are modulated by neurotransmitters is also variable. This study was directed at testing the hypothesis that a major source of this variability is recording from multiple populations of pyramidal cells. We used the whole cell patch-clamp technique to record from dissociated corticocortical, corticostriatal, and corticotectal projecting pyramidal cells. There were significant differences between the three pyramidal cell types in the mean percentage of L-, P-, and N-type Ca2+ currents. For both N- and P-type currents, the range of percentages expressed was small for corticostriatal and corticotectal cells as compared with cells which project to the corpus callosum or to the general population. The variance was significantly different between cell types for N- and P-type currents. These results suggest that an important source of the variability in the proportions of Ca2+ current types present in neocortical pyramidal neurons is recording from multiple populations of pyramidal cells.

Dihydropyridine- and Neurotoxin-Sensitive and -Insensitive Calcium Currents in Acutely Dissociated Neurons of the Rat Central Amygdala

1997 ◽  
Vol 77 (2) ◽  
pp. 690-701 ◽  
Author(s):  
Baojian Yu ◽  
Patricia Shinnick-Gallagher
Keyword(s):  
Calcium Current ◽  
Calcium Currents ◽  
Similar Proportion ◽  
Central Amygdala ◽  
Patch Clamp Recording ◽  
Whole Cell ◽  
Whole Cell Patch Clamp ◽  
Moderate Rate ◽  
Rate Of Decay ◽  
P Type

Yu, Baojian and Patricia Shinnick-Gallagher. Dihydropyridine- and neurotoxin-sensitive and -insensitive calcium currents in acutely dissociated neurons of the rat central amygdala. J. Neurophysiol. 77: 690–701, 1997. The central amygdala (CeA) is an area involved in emotional learning and stress, and identification of Ca2+ currents is essential to understanding interneuronal communication through this nucleus. The purpose of this study was to separate and characterize dihydropyridine (DHP)- and neurotoxin-sensitive and -resistant components of the whole cell Ca2+ current ( I Ca) in acutely dissociated rat CeA neurons with the use of whole cell patch-clamp recording. Saturating concentrations of nimodipine (NIM, 5 μM), a DHP antagonist, blocked 22% of I Ca; this NIM-sensitive (L-type) current was recorded in 68% of CeA neurons. The DHP agonist Bay K 8644 (5 μM) produced a 36% increase in I Ca in a similar proportion of CeA neurons (70%). ω-Conotoxin GVIA (CgTx GVIA, 1 μM) in saturating concentrations inhibited 30% of I Ca, whereas ω-agatoxin IVA (Aga IVA, 100 nM), in concentrations known to block P-type currents, did not affect I Ca. Higher concentrations of Aga IVA (1 μM) alone reduced I Ca by 34%, but in the presence of NIM (5 μM) and CgTx GVIA (1 μM) blocked only 18% of I Ca. ω-Conotoxin MVIIC (CgTx MVIIC, 250 nM) reduced I Ca by 13% in the presence of CgTx GVIA (1 μM). Application of NIM (5 mM), CgTx GVIA (1 μM), and Aga IVA (1 μM) blocked ∼67% of I Ca. A similar portion (63%) of Ca2+ current was blocked with CgTx MVIIC (250 nM) in the presence of NIM (5 μM) and CgTx GVIA (1 μM). The current resistant to NIM and the neurotoxins represented 37% of I Ca, whereas in neurons not having L-type currents the resistant current made up ∼53% of I Ca (49 ± 2%, mean ± SE). The resistant current activated at around −40 mV and peaked at ∼0 mV with half-activation and -inactivation potentials of −17 and −58 mV and slopes for activation and inactivation of −5 and 13 mV, respectively. The resistant current was sensitive to Cd2+ (IC50 = 2.5 μM) and Ni2+ (IC50 = 86 μM), was larger in Ca2+ than in Ba2+ (ratio = 1.31:1), and showed a moderate rate of decay. In summary, our results show that the high-voltage-activated calcium current in rat CeA neurons is composed of at least four pharmacologically distinct components: L-type current (NIM sensitive, 22%), N-type current (CgTx GVIA sensitive, 30%), Q-type current [Aga IVA (1 μM) and CgTx MVIIC sensitive, ∼13–18%], and a resistant current (Non-L, -N, and -Q current, 33 ∼ 37%), amounting to 37–53% of the total current. The resistant current has some electrophysiological and pharmacological characteristics in common with doe-1, α1E, and R-type calcium currents, but remains unclassified.

scholarly journals Thapsigargin-induced Ca2+ mobilization in acutely isolated mouse lacrimal acinar cells is dependent on a basal level of Ins(1,4,5)P3 and is inhibited by heparin

1994 ◽  
Vol 299 (1) ◽  
pp. 37-40 ◽  
Author(s):  
P M Smith ◽  
D V Gallacher
Keyword(s):  
Patch Clamp ◽  
Atpase Activity ◽  
Receptor Antagonist ◽  
Acinar Cells ◽  
Cell Types ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Whole Cell Patch Clamp ◽  
Subsequent Exposure ◽  
Lacrimal Acinar Cells

The tumour-promoting agent thapsigargin has been shown to inhibit the microsomal Ca(2+)-ATPase and cause Ca2+ mobilization in a variety of cell types including exocrine acinar cells [Bird, Obie and Putney (1992) J. Biol. Chem. 267, 18382-18386]. When applied to acutely isolated lacrimal acinar cells, thapsigargin caused a slow biphasic activation of both the Ca(2+)-dependent K+ and Cl- currents measured using the whole-cell patch-clamp technique. If the only action of thapsigargin is to inhibit sequestration into Ca2+ pools, then Ca2+ mobilization following exposure to thapsigargin indicates that there is a significant ‘leak’ of Ca2+ into the cytoplasm, which is normally countered by Ca(2+)-ATPase activity. In the present study, we introduced the Ins(1,4,5)P3 receptor antagonist heparin (200 micrograms/ml) into lacrimal acinar cells via the patch-clamp pipette. Following a 5 min preincubation in the presence of heparin, neither acetylcholine (1 microM) nor thapsigargin (1 microM) caused any significant increase in either Ca(2+)-dependent current. Caffeine has been shown to suppress basal Ins(1,4,5)P3 levels in exocrine acinar cells [Toescu, O'Neill, Petersen and Eisner (1992) J. Biol. Chem. 267, 23467-23470]. Preincubation with caffeine (10 mM) also inhibited the response to subsequent exposure to thapsigargin. These data suggest that, in acutely isolated lacrimal cells, the source of the Ca2+ leak which gives rise to Ca2+ mobilization following inhibition of Ca2+ re-uptake by thapsigargin is Ca2+ release, from Ins(1,4,5)P3-dependent Ca2+ pools, caused by resting Ins(1,4,5)P3 levels.

scholarly journals Spike Frequency Adaptation and Neocortical Rhythms

2002 ◽  
Vol 88 (2) ◽  
pp. 761-770 ◽  
Author(s):  
Galit Fuhrmann ◽  
Henry Markram ◽  
Misha Tsodyks
Keyword(s):  
Firing Rate ◽  
Pyramidal Neurons ◽  
Spike Frequency ◽  
Spike Frequency Adaptation ◽  
Patch Clamp Technique ◽  
Response Characteristics ◽  
Frequency Adaptation ◽  
Whole Cell Patch Clamp ◽  
The Mean

Spike-frequency adaptation in neocortical pyramidal neurons was examined using the whole cell patch-clamp technique and a phenomenological model of neuronal activity. Noisy current was injected to reproduce the irregular firing typically observed under in vivo conditions. The response was quantified by computing the poststimulus histogram (PSTH). To simulate the spiking activity of a pyramidal neuron, we considered an integrate-and-fire model to which an adaptation current was added. A simplified model for the mean firing rate of an adapting neuron under noisy conditions is also presented. The mean firing rate model provides a good fit to both experimental and simulation PSTHs and may therefore be used to study the response characteristics of adapting neurons to various input currents. The models enable identification of the relevant parameters of adaptation that determine the shape of the PSTH and allow the computation of the response to any change in injected current. The results suggest that spike frequency adaptation determines a preferred frequency of stimulation for which the phase delay of a neuron's activity relative to an oscillatory input is zero. Simulations show that the preferred frequency of single neurons dictates the frequency of emergent population rhythms in large networks of adapting neurons. Adaptation could therefore be one of the crucial factors in setting the frequency of population rhythms in the neocortex.

Multiple high-threshold calcium currents in acutely isolated rat amygdaloid pyramidal cells

1994 ◽  
Vol 71 (1) ◽  
pp. 433-436 ◽  
Author(s):  
R. C. Foehring ◽  
R. S. Scroggs
Keyword(s):  
Pyramidal Cells ◽  
Amygdaloid Complex ◽  
Calcium Currents ◽  
High Threshold ◽  
Whole Cell ◽  
Cell Current ◽  
P Type ◽  
Whole Cell Current ◽  
Isolated Rat

1. High-threshold Ca2+ currents were studied in large pyramidal cells acutely dissociated from the rat amygdaloid complex. L-, N-, and P-type currents were present in about equal proportions in these cells and accounted for most of the whole-cell current.

Serotonin modulates N- and P-type calcium currents in neocortical pyramidal neurons via a membrane-delimited pathway

1996 ◽  
Vol 75 (2) ◽  
pp. 648-659 ◽  
Author(s):  
R. C. Foehring
Keyword(s):  
Pyramidal Neurons ◽  
Calcium Currents ◽  
Whole Cell ◽  
5Ht1a Receptors ◽  
Cell Current ◽  
Agonist Concentration ◽  
P Type ◽  
Channel Currents ◽  
Dose Dependent ◽  
Neocortical Pyramidal Neurons

1. The effects of serotonin (5HT) on neocortical pyramidal neurons were studied using whole cell and ON-cell patch-clamp recordings from acutely dissociated neurons. 2. 5HT decreased high voltage-activated calcium channel currents in a dose-dependent and reversible manner in acutely dissociated neocortical pyramidal neurons. The maximum block was 30% of the peak whole cell current (at -10 mV). 3. The 5HT modulation was mimicked by 5HT1A agonists and was reduced by 5HT1A antagonists. 5HT2 antagonists had no effect on the modulation. These data suggest that the 5HT effects were mediated by 5HT1A receptors. 4. The 5HT1A modulation was reduced in the presence of the specific N-type blocker omega-conotoxin GVIA (CgTx) and by the P-type channel blocker omega-agatoxin IVA (AgTx), but not by the L-type blocker nifedipine. 5HT did not modulate the slowed tail currents in the presence of the dihydropyridine agonist Bay K 8644. These data suggest that N- and P-type channels (but not L-type channels) were targeted by 5HT. 5. The modulation involved G proteins and utilized a membrane-delimited pathway. The modulation was rapid in onset (tau approximately 600 ms) and offset. About 50% of the reduction in current by 5HT1A agonists was overcome by prepulses to 120 mV. 6. Slowing of current onset kinetics in response to 5HT1A agonists was seen rarely in neocortical pyramidal neurons (11% of cases). The presence of slowing depended on agonist concentration, being evident only with high micromolar doses.

Direct demonstration of functional disconnection by anoxia of inhibitory interneurons from excitatory inputs in rat hippocampus

1995 ◽  
Vol 73 (1) ◽  
pp. 421-426 ◽  
Author(s):  
P. Congar ◽  
R. Khazipov ◽  
Y. Ben-Ari
Keyword(s):  
Pyramidal Neurons ◽  
Hippocampal Slices ◽  
Reversal Potential ◽  
Pyramidal Cells ◽  
Stratum Radiatum ◽  
Patch Clamp Technique ◽  
Ca1 Region ◽  
Whole Cell Patch Clamp ◽  
Direct Demonstration ◽  
Outward Currents

1. We studied the effects of anoxia on excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) evoked by electrical stimulation in the stratum radiatum in concomitantly recorded pyramidal cells and interneurons of the CA1 region of rat hippocampal slices. We used the blind whole cell patch-clamp technique, and anoxia was induced by switching perfusion of the slice from oxygenated artificial cerebral spinal fluid (ACSF) to ACSF saturated with 95% N2-5% CO2 for 4-6 min. 2. As in pyramidal neurons, anoxia induced in interneurons outward currents, during and shortly after the anoxic episode. Both currents were, however, significantly larger in interneurons than in pyramidal neurons. 3. EPSCs are more rapidly depressed by anoxia in interneurons than in simultaneously recorded pyramidal cells. 4. In pyramidal neurons, polysynaptic IPSCs (pIPSCs) evoked by conventional distant stimulation (> 1 mm) are more sensitive to anoxia then EPSCs. In contrast, in interneurons, anoxia blocks with a similar latency EPSCs and polysynaptic IPSCs. 5. To determine whether this block of pIPSCs in pyramidal cells is due to a shift in driving force or a change in conductance, we examined the current (I/V) relationships. The block by anoxia of pIPSCs is due to a reduction of IPSC conductance (> 98%) that occlude other events including the shift of IPSCs reversal potential (ECl).(ABSTRACT TRUNCATED AT 250 WORDS)

Concentration Dependence of Bicarbonate-Induced Calcium Current Modulation

2000 ◽  
Vol 84 (5) ◽  
pp. 2277-2283 ◽  
Author(s):  
C. Bruehl ◽  
W. J. Wadman ◽  
O. W. Witte
Keyword(s):  
Calcium Currents ◽  
Hill Coefficient ◽  
Patch Clamp Technique ◽  
Ca1 Neurons ◽  
Bicarbonate Ions ◽  
Whole Cell Patch Clamp ◽  
The Mean ◽  
The Hill ◽  
Maximal Shift ◽  
Pathological Situation

High-voltage–activated calcium currents (HVA) of CA1 neurons are prominently attenuated following a switch from HEPES-buffered solution to one buffered with CO2/HCO3 −. In the present study we investigated whether bicarbonate ions or the dissolved CO2 induce this alteration in current characteristic. The study was carried out on freshly isolated CA1 neurons using the whole cell patch-clamp technique. Maximal calcium conductance and the mean peak amplitude of the currents showed a concentration-dependent decrease when cells were consecutively bathed in solutions containing increasing amounts of bicarbonate and CO2. This decrease is best described by the Hill equation, yielding a maximal attenuation of 69%, a half-maximal concentration (EC50) of 7.4 mM HCO3 −, and a Hill coefficient of 1.8. In parallel, the potentials of half-maximal activation ( V h,a) and inactivation ( V h,i) were linearly shifted in hyperpolarizing direction with a maximal shift, in the 10% CO2/37 mM HCO3 − containing solution of 10 ± 1 mV for V h,a( n = 23) and 17 ± 1.4 mV for V h,i ( n = 18). When currents were evoked in solutions containing equal concentrations of bicarbonate but different amounts of CO2, only nonsignificant changes were observed, while marked alterations of the currents were induced when bicarbonate was changed and CO2 held stable. The experiments suggest that bicarbonate is the modulating agent and not CO2. This bicarbonate-induced modulation may be of critical relevance for the excitation level of the CNS under pathological situation with altered concentration of this ion, such as hyperventilation and metabolic acidosis.

scholarly journals Control of impulsivity by Gi-protein signalling in layer-5 pyramidal neurons of the anterior cingulate cortex

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Bastiaan van der Veen ◽  
Sampath K. T. Kapanaiah ◽  
Kasyoka Kilonzo ◽  
Peter Steele-Perkins ◽  
Martin M. Jendryka ◽  
...  
Keyword(s):  
Gene Expression ◽  
Anterior Cingulate Cortex ◽  
Expression Analysis ◽  
Gene Expression Analysis ◽  
Pyramidal Neurons ◽  
Treatment Options ◽  
Pyramidal Cells ◽  
Cingulate Cortex ◽  
Cell Types ◽  
Anterior Cingulate

AbstractPathological impulsivity is a debilitating symptom of multiple psychiatric diseases with few effective treatment options. To identify druggable receptors with anti-impulsive action we developed a systematic target discovery approach combining behavioural chemogenetics and gene expression analysis. Spatially restricted inhibition of three subdivisions of the prefrontal cortex of mice revealed that the anterior cingulate cortex (ACC) regulates premature responding, a form of motor impulsivity. Probing three G-protein cascades with designer receptors, we found that the activation of Gi-signalling in layer-5 pyramidal cells (L5-PCs) of the ACC strongly, reproducibly, and selectively decreased challenge-induced impulsivity. Differential gene expression analysis across murine ACC cell-types and 402 GPCRs revealed that - among Gi-coupled receptor-encoding genes - Grm2 is the most selectively expressed in L5-PCs while alternative targets were scarce. Validating our approach, we confirmed that mGluR2 activation reduced premature responding. These results suggest Gi-coupled receptors in ACC L5-PCs as therapeutic targets for impulse control disorders.

scholarly journals CRISPR/Cas9 Mediated Knock Down of δ-ENaC Blunted the TNF-Induced Activation of ENaC in A549 Cells

2021 ◽  
Vol 22 (4) ◽  
pp. 1858
Author(s):  
Waheed Shabbir ◽  
Nermina Topcagic ◽  
Mohammed Aufy ◽  
Murat Oz
Keyword(s):  
A549 Cells ◽  
Na Channel ◽  
Na Current ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Knock Down ◽  
Whole Cell Patch Clamp ◽  
Glycosylation Sites ◽  
Epithelial Na Channel

Tumor necrosis factor (TNF) is known to activate the epithelial Na+ channel (ENaC) in A549 cells. A549 cells are widely used model for ENaC research. The role of δ-ENaC subunit in TNF-induced activation has not been studied. In this study we hypothesized that δ-ENaC plays a major role in TNF-induced activation of ENaC channel in A549 cells which are widely used model for ENaC research. We used CRISPR/Cas 9 approach to knock down (KD) the δ-ENaC in A549 cells. Western blot and immunofluorescence assays were performed to analyze efficacy of δ-ENaC protein KD. Whole-cell patch clamp technique was used to analyze the TNF-induced activation of ENaC. Overexpression of wild type δ-ENaC in the δ-ENaC KD of A549 cells restored the TNF-induced activation of whole-cell Na+ current. Neither N-linked glycosylation sites nor carboxyl terminus domain of δ-ENaC was necessary for the TNF-induced activation of whole-cell Na+ current in δ-ENaC KD of A549 cells. Our data demonstrated that in A549 cells the δ-ENaC plays a major role in TNF-induced activation of ENaC.

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