Local Excitatory Circuits in the Intermediate Gray Layer of the Superior Colliculus

1999 ◽  
Vol 81 (3) ◽  
pp. 1424-1427 ◽  
Author(s):  
Diana L. Pettit ◽  
Matthew C. Helms ◽  
Psyche Lee ◽  
George J. Augustine ◽  
William C. Hall
Keyword(s):  
Superior Colliculus ◽  
Intermediate Layer ◽  
Tree Shrew ◽  
Patch Clamp Recording ◽  
Inward Current ◽  
Whole Cell Patch Clamp ◽  
Synaptic Interactions ◽  
Layer Neuron ◽  
Inward Currents ◽  
Synaptic Responses

Local excitatory circuits in the intermediate gray layer of the superior colliculus. We have used photostimulation and whole cell patch-clamp recording techniques to examine local synaptic interactions in slices from the superior colliculus of the tree shrew. Uncaging glutamate 10–75 μm from the somata of neurons in the intermediate gray layer elicited a long-lasting inward current, due to direct activation of glutamate receptors on these neurons, and brief inward currents caused by activation of presynaptic neurons. The synaptic responses occurred as individual currents or as clusters that lasted up to several hundred milliseconds. Excitatory synaptic responses, which reversed at membrane potentials near 0 mV, could be evoked by uncaging glutamate anywhere within 75 μm of an intermediate layer neuron. Our results indicate the presence of extensive local excitatory circuits in the intermediate layer of the superior colliculus and support the hypothesis that such intrinsic circuitry contributes to the development of presaccadic command bursts.

The effects of glycine and GABA on isolated horizontal cells from the salamander retina

1991 ◽  
Vol 66 (6) ◽  
pp. 2002-2013 ◽  
Author(s):  
T. A. Gilbertson ◽  
S. Borges ◽  
M. Wilson
Keyword(s):  
Horizontal Cell ◽  
Horizontal Cells ◽  
Gamma Aminobutyric Acid ◽  
Light Responses ◽  
Whole Cell Patch Clamp ◽  
Synaptic Interactions ◽  
Outward Currents ◽  
Na Currents ◽  
Inward Currents ◽  
Kinetics Of

1. Horizontal cells, identified by their morphology, were isolated from the salamander retina and examined in whole cell patch clamp. 2. All cells showed large outward currents activating positive to about -50 mV, and a minority of cells showed fast, tetrodotoxin-suppressible Na+ currents. Slow inward currents that might shape the light responses were never observed. 3. All cells showed conductance increases to both gamma-aminobutyric acid (GABA) and glycine that were completely blocked by bicuculline and strychnine, respectively. No cross-blocking by these antagonists was observed. Partial replacements of Cl- with large, impermeant anions indicated that both GABA- and glycine-evoked currents were carried by Cl- ions. 4. Responses to both GABA and glycine desensitized strongly with time constants of approximately 2 s. 5. Responses to glutamate were not enhanced by glycine. Similarly, responses to GABA were not enhanced by glutamate. 6. GABA-mediated synaptic interactions between horizontal cells may account for the changes in the kinetics of horizontal cell light responses seen when glycine is applied to the intact retina.

Vasopressin-Induced Currents in Rat Neonatal Spinal Lateral Horn Neurons Are G-Protein Mediated and Involve Two Conductances

1998 ◽  
Vol 80 (4) ◽  
pp. 1900-1910 ◽  
Author(s):  
Miloslav Kolaj ◽  
Leo P. Renaud
Keyword(s):  
Spinal Cord ◽  
G Protein ◽  
Wide Distribution ◽  
Channel Blockers ◽  
Patch Clamp Recording ◽  
Inward Current ◽  
Lateral Column ◽  
Lateral Horn ◽  
Inward Currents ◽  
Induced Currents

Kolaj, Miloslav and Leo P. Renaud. Vasopressin-induced currents in rat neonatal spinal lateral horn neurons are G-protein mediated and involve two conductances . J. Neurophysiol. 80: 1900–1910, 1998. Arginine vasopressin (AVP) receptors are expressed early in the developing spinal cord. To characterize AVP-induced conductances in lower thoracic sympathetic preganglionic (SPN) and other lateral horn neurons, we used patch-clamp recording techniques in neonatal (11–21 days) rat spinal cord slices. Most (90%) of 273 neurons, including all 68 SPNs, responded to AVP with membrane depolarization and/or a V1 receptor-mediated, dose-dependent (0.01–1.0 μM) and tetrodotoxin (TTX)-resistant inward current. A role for G-proteins was indicated by persistence of this inward current after intracellular dialysis with GTP-γ-S or GMP-PNP, its marked reduction with GDP-β-S, and significant reduction, but not abolition, after preincubation with pertussis toxin or in the presence of N-ethylmaleimide. Analysis of individual current-voltage ( I- V) relationships in 57 cells indicated the presence of two different membrane conductances. In 21 cells, net AVP-induced currents reversed around −103 mV, reflecting reduction in one or more barium-sensitive potassium conductances; in 12 cells, net AVP-induced current reversed around −40 mV and was not significantly sensitive to several potassium channel blockers including barium, tetraethylammonium chloride (TEA), 4-aminopyridine (4AP), cesium, or glibenclamide, suggesting increase in a nonselective cationic conductance that was separate from I h; in 24 cells where I- V lines shifted in parallel, AVP-induced inward currents were significantly greater and probably involved both conductances. These data indicate that SPNs and a majority of unidentified neonatal lateral horn neurons possess functional G-protein–coupled V1-type vasopressin receptors. The wide distribution of AVP receptors in neonatal spinal lateral column cells suggests a role that may extend beyond involvement in regulation of autonomic nervous system function.

Activation of subfornical organ neurons in rats through pre- and postsynaptic α-adrenoceptors

2006 ◽  
Vol 290 (6) ◽  
pp. R1646-R1653 ◽  
Author(s):  
Eiko Honda ◽  
Kentaro Ono ◽  
Shinji Kataoka ◽  
Kiyotoshi Inenaga
Keyword(s):  
Gaba Receptor ◽  
Membrane Conductance ◽  
Subfornical Organ ◽  
Patch Clamp Recording ◽  
Pcr Assay ◽  
Whole Cell Patch Clamp ◽  
Outward Currents ◽  
Current Clamp Mode ◽  
Inward Currents ◽  
Pulse Stimulation

The effects of noradrenaline (NA) and its analogs on subfornical organ (SFO) neurons in rat slice preparations were investigated by using whole cell patch-clamp recording. In the current-clamp mode, the application of NA at 10–100 μM produced membrane depolarization (63%, 17 responsive neurons/27 neurons tested) and hyperpolarization (22%, 6/27 neurons). In the voltage-clamp mode, NA application at 1–100 μM produced inward currents (69%, 42/61 neurons) and outward currents (23%, 14/61 neurons). These currents remained in the presence of TTX or both glutamate and GABA receptor antagonists. In most of the neurons (25/31 neurons) showing inward currents in the presence of NA, the membrane conductance was not changed by voltage ramps or hyperpolarizing pulse stimulation. Similar responses were obtained by the application of the α1-agonist phenylephrine. The phenylephrine-induced inward currents were inhibited by the α1-antagonist prazosin. The α2-agonist clonidine decreased the frequency of spontaneous GABAergic inhibitory postsynaptic currents (4/10 neurons). In addition, RT-PCR assay and immunohistochemical staining showed the existence of α1-adrenoceptors in the SFO. The results suggest that SFO neurons in rats are activated postsynaptically through α1-adrenoceptors and that the activation is enhanced by suppressing GABAergic inhibitory synaptic inputs through presynaptic α2-adrenoceptors.

scholarly journals Large-Conductance Calcium-Activated Potassium Channels and Voltage-Dependent Sodium Channels in Human Cementoblasts

2021 ◽  
Vol 12 ◽  
Author(s):  
Satomi Kamata ◽  
Maki Kimura ◽  
Sadao Ohyama ◽  
Shuichiro Yamashita ◽  
Yoshiyuki Shibukawa
Keyword(s):  
Alveolar Bone ◽  
Attachment Site ◽  
Ionic Currents ◽  
Ionic Channels ◽  
Patch Clamp Recording ◽  
Physiological Processes ◽  
Whole Cell Patch Clamp ◽  
Outward Currents ◽  
Voltage Dependent ◽  
Inward Currents

Cementum, which is excreted by cementoblasts, provides an attachment site for collagen fibers that connect to the alveolar bone and fix the teeth into the alveolar sockets. Transmembrane ionic signaling, associated with ionic transporters, regulate various physiological processes in a wide variety of cells. However, the properties of the signals generated by plasma membrane ionic channels in cementoblasts have not yet been described in detail. We investigated the biophysical and pharmacological properties of ion channels expressed in human cementoblast (HCEM) cell lines by measuring ionic currents using conventional whole-cell patch-clamp recording. The application of depolarizing voltage steps in 10 mV increments from a holding potential (Vh) of −70 mV evoked outwardly rectifying currents at positive potentials. When intracellular K+ was substituted with an equimolar concentration of Cs+, the outward currents almost disappeared. Using tail current analysis, the contributions of both K+ and background Na+ permeabilities were estimated for the outward currents. Extracellular application of tetraethylammonium chloride (TEA) and iberiotoxin (IbTX) reduced the densities of the outward currents significantly and reversibly, whereas apamin and TRAM-34 had no effect. When the Vh was changed to −100 mV, we observed voltage-dependent inward currents in 30% of the recorded cells. These results suggest that HCEM express TEA- and IbTX-sensitive large-conductance Ca2+-activated K+ channels and voltage-dependent Na+ channels.

GABA-Mediated Inhibition of Glutamate Release During Ischemia in Substantia Gelatinosa of the Adult Rat

2003 ◽  
Vol 89 (1) ◽  
pp. 257-264 ◽  
Author(s):  
Noriaki Matsumoto ◽  
Eiichi Kumamoto ◽  
Hidemasa Furue ◽  
Megumu Yoshimura
Keyword(s):  
Glutamate Release ◽  
Control Level ◽  
Outward Current ◽  
Substantia Gelatinosa ◽  
Slow Inward Current ◽  
Patch Clamp Technique ◽  
Inward Current ◽  
Adult Rat ◽  
Whole Cell Patch Clamp ◽  
Inward Currents

An ischemia-induced change in glutamatergic transmission was investigated in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by use of the whole cell patch-clamp technique; the ischemia was simulated by superfusing an oxygen- and glucose-free medium (ISM). Following ISM superfusion, 21 of 37 SG neurons tested produced an outward current (23 ± 4 pA at a holding potential of −70 mV), which was followed by a slow and subsequent rapid inward current; the remaining neurons had only inward currents. During such a change in holding currents, spontaneous excitatory postsynaptic currents (EPSCs) were remarkably decreased in a frequency with time (half-decay time of the frequency: about 65 s). The frequency of spontaneous EPSCs was reduced to 28 ± 13% ( n = 37) of the control level during the generation of the slow inward current (about 4 min after the beginning of ISM superfusion) without a change in the amplitude of spontaneous EPSCs. When ISM was superfused together with either bicuculline (10 μM) or CGP35348 (20 μM; GABAA and GABAB receptor antagonists, respectively), spontaneous EPSC frequency reduced by ISM recovered to the control level and then the frequency markedly increased [by 325 ± 120% ( n = 22) and 326 ± 91% ( n = 17), respectively, 4 min after ISM superfusion]; this alteration in the frequency was not accompanied by a change in spontaneous EPSC amplitude. Superfusing TTX (1 μM)-containing ISM resulted in a similar recovery of spontaneous EPSC frequency and following increase (by 328 ± 26%, n = 12) in the frequency; strychnine (1 μM) did not affect ISM-induced changes in spontaneous EPSC frequency ( n = 5). It is concluded that the ischemic simulation inhibits excitatory transmission to SG neurons, whose action is in part mediated by the activation of presynaptic GABAAand GABAB receptors, probably due to GABA released from interneurons as a result of an ischemia-induced increase in neuronal activities. This action might protect SG neurons from an excessive excitation mediated by l-glutamate during ischemia.

Participation of Ca currents in colonic electrical activity

1989 ◽  
Vol 257 (3) ◽  
pp. C451-C460 ◽  
Author(s):  
P. D. Langton ◽  
E. P. Burke ◽  
K. M. Sanders
Keyword(s):  
Slow Waves ◽  
Ca Current ◽  
Patch Clamp Technique ◽  
Inward Current ◽  
Whole Cell Patch Clamp ◽  
Mechanical Threshold ◽  
Inward Currents ◽  
Window Current ◽  
The Relationship ◽  
Ca Currents

Canine colonic myocytes were studied with the whole cell patch-clamp technique. In 1.8 mM Ca2+, inward currents were evoked by depolarization. Currents activated positive to -50 mV, peaked at approximately 0 mV, and reversed at approximately +50 mV. Inward current was potentiated by high external Ca2+ concentration and BAY K8644 and was decreased by low external Ca2+, nifedipine, and Mn2+, indicating that the current was carried by Ca2+. Overlap of the activation-inactivation properties indicated a "window current" range (-40 to -20 mV) in which inward current might be sustained for long durations at potentials achieved during electrical slow waves. Voltage-clamp protocols simulating physiological depolarizations elicited sustained inward currents. Maximum changes in intracellular Ca2+ resulting from sustained inward currents were calculated, which suggested that depolarizations at the level of slow waves may increase cell Ca2+ sufficiently to cause contraction. The data suggest that electrical slow waves in colonic myocytes are due in part to inward Ca current. This current appears to be sufficient to explain the relationship between slow waves and contractions and provides an explanation for the mechanical threshold in colonic muscles.

Site of synaptic depression during hypoxia: a patch-clamp analysis

1993 ◽  
Vol 69 (2) ◽  
pp. 432-441 ◽  
Author(s):  
N. Hershkowitz ◽  
A. N. Katchman ◽  
S. Veregge
Keyword(s):  
Patch Clamp ◽  
Kynurenic Acid ◽  
Hippocampal Slices ◽  
Slow Inward Current ◽  
Transient Outward Current ◽  
Synaptic Response ◽  
Patch Clamp Recording ◽  
Postsynaptic Response ◽  
Inward Current ◽  
Inward Currents

1. The effect of hypoxia on synaptic physiology was investigated in hippocampal slices from 16- to 23-day-old rats. CA1 pyramidal cells were examined by whole cell patch-clamp recording, and hypoxia was induced by switching perfusion of the slice from oxygenated artificial cerebrospinal fluid (ACSF) to ACSF saturated with 95% N2-5%CO2. Synaptic responses were assessed by stimulating the Schaffer collateral-commissural projection with an electrode in the stratum radiatum every 20 s. 2. Within 100-200 s of the onset of hypoxia, the orthrodromically elicited synaptic response of the CA1 cells was largely inhibited. In addition, a slow inward current was observed after the onset of hypoxia. A transient outward current, preceding the inward current, was observed in only 2 of 17 cells examined. The slow inward current culminated in an irreversible rapid inward current at approximately 140 s after hypoxia. This rapid inward current occurred simultaneously with spreading depression as measured by field potentials. Tetrodotoxin (TTX) had no effect on the onset of this current, whereas kynurenic acid significantly delayed its occurrence. 3. Before the onset of hypoxia, spontaneous transient inward currents were apparent. The frequency of these events increased by three- to fourfold after hypoxia. The transient inward currents persisted in slices incubated in TTX, but were almost completely inhibited in slices incubated with the mixed N-methyl-D-aspartate (NMDA)/non-NMDA antagonist kynurenic acid. This identified the spontaneous events that were increased in frequency by hypoxia as glutamatergic miniature excitatory postsynaptic currents (mEPSCs). 4. The mean amplitude of the mEPSCs was not affected by hypoxia at a time at which the orthodromically elicited synaptic response was almost completely inhibited by hypoxia. In addition, the response of the postsynaptic cell to pressure ejection of glutamate was not inhibited under conditions of nearly complete blocked the synaptic response. Thus, by two measures, the postsynaptic response was not affected by hypoxia, indicating that the site of hypoxia-induced synaptic failure was at the presynaptic terminal. 5. The orthodromically elicited synaptic response consisted of an EPSC followed closely by an inhibitory postsynaptic current (IPSC). The IPSC portion of the elicited postsynaptic response was more sensitive to inhibition by hypoxia than was the EPSC. In some cells the EPSC exhibited a monophasic decline in amplitude during hypoxia. However, in a majority of cells, an initial decline in the amplitude of the EPSC was followed by a transient increase and subsequent depression.(ABSTRACT TRUNCATED AT 400 WORDS)

Organization of the Intermediate Gray Layer of the Superior Colliculus. I. Intrinsic Vertical Connections

2004 ◽  
Vol 91 (4) ◽  
pp. 1706-1715 ◽  
Author(s):  
Matthew C. Helms ◽  
Gülden Özen ◽  
William C. Hall
Keyword(s):  
Superior Colliculus ◽  
Superficial Layer ◽  
Wide Field ◽  
Visually Guided ◽  
Patch Clamp Recording ◽  
Visuomotor Integration ◽  
Whole Cell Patch Clamp ◽  
Spatial Attributes ◽  
Caged Glutamate

A pathway from the superficial visual layers to the intermediate premotor layers of the superior colliculus has been proposed to mediate visually guided orienting movements. In these experiments, we combined photostimulation using “caged” glutamate with in vitro whole cell patch-clamp recording to demonstrate this pathway in the rat. Photostimulation in the superficial gray and optic layers (SGS and SO, respectively) evoked synaptic responses in intermediate gray layer (SGI) cells. The responses comprised individual excitatory postsynaptic currents (EPSCs) or EPSC clusters. Blockade of these EPSCs by TTX confirmed that they were synaptically mediated. Stimulation within a column (∼500 μm diam) extending superficially from the recorded cell evoked the largest and most reliable responses, but off-axis stimuli were effective as well. The EPSCs could be evoked by stimuli 1,000 μm off-axis from the postsynaptic neuron. The dimensions of this wider region (∼2 mm diam) corresponded to those of the dendrites of superficial layer wide-field neurons. SGI neurons differed in their input from SGS and SO; neurons in the middle of the intermediate layer (SGIb) were less likely to respond to visual layer photostimulation than were those in sublayers just above and below them. However, focal stimulation within SGIa did evoke responses within SGIb, indicating that SGIb neurons may receive input from the visual layers indirectly. These results demonstrate a columnar pathway that may mediate visually guided orienting movements, but the results also reveal spatial attributes of the pathway which imply that it also plays a more complex role in visuomotor integration.

Acid-sensing ion channels contribute to the increase in vesicular release from SH-SY5Y cells stimulated by extracellular protons

2012 ◽  
Vol 303 (4) ◽  
pp. C376-C384 ◽  
Author(s):  
Qiu-Ju Xiong ◽  
Zhuang-Li Hu ◽  
Peng-Fei Wu ◽  
Lan Ni ◽  
Zhi-Fang Deng ◽  
...  
Keyword(s):  
Ion Channels ◽  
Neurotransmitter Release ◽  
Neuronal Cell ◽  
Channel Blockers ◽  
Patch Clamp Recording ◽  
Human Neuroblastoma ◽  
Whole Cell Patch Clamp ◽  
Acid Sensing Ion Channels ◽  
Vesicular Release ◽  
Inward Currents

Acid-sensing ion channels (ASICs) have been reported to play a role in the neuronal dopamine pathway, but the exact role in neurotransmitter release remains elusive. Human neuroblastoma SH-SY5Y is a dopaminergic neuronal cell line, which can release monoamine neurotransmitters. In this study, the expression of ASICs was identified in SH-SY5Y cells to further explore the role of ASICs in vesicular release stimulated by acid. We gathered evidence that ASICs could be detected in SH-SY5Y cells. In whole cell patch-clamp recording, a rapid decrease in extracellular pH evoked inward currents, which were reversibly inhibited by 100 μM amiloride. The currents were pH dependent, with a pH of half-maximal activation (pH0.5) of 6.01 ± 0.04. Furthermore, in calcium imaging and FM 1-43 dye labeling, it was shown that extracellular protons increased intracellular calcium levels and vesicular release in SH-SY5Y cells, which was attenuated by PcTx1 and amiloride. Interestingly, N-type calcium channel blockers inhibited the vesicular release induced by acidification. In conclusion, ASICs are functionally expressed in SH-SY5Y cells and involved in vesicular release stimulated by acidification. N-type calcium channels may be involved in the increase in vesicular release induced by acid. Our results provide a preliminary study on ASICs in SH-SY5Y cells and neurotransmitter release, which helps to further investigate the relationship between ASICs and dopaminergic neurons.

Three types of slow inward currents as distinguished by melittin in 3-day-old embryonic heart

1988 ◽  
Vol 66 (8) ◽  
pp. 1017-1022 ◽  
Author(s):  
G. Bkaily ◽  
D. Jacques ◽  
T. Yamamoto ◽  
A. Sculptoreanu ◽  
M. D. Payet ◽  
...  
Keyword(s):  
Slow Inward Current ◽  
Heart Cells ◽  
Slow Inactivation ◽  
High Concentration ◽  
Patch Clamp Technique ◽  
Inward Current ◽  
Whole Cell Patch Clamp ◽  
Low Concentrations ◽  
Voltage Dependent ◽  
Inward Currents

Membrane slow inward currents of 3-day-old embryonic chick single heart cells were investigated using the whole-cell patch clamp technique. In a solution containing only Na+ ions and in the presence of tetrodotoxin and Mn2+, the inward current–voltage relationship presented two maxima, confirming the existence of two different voltage-dependent slow inward currents. The first type, a fast transient slow inward current (Isi (ft)), was activated from a holding potential of −80 mV and showed fast activation and inactivation. This current was highly sensitive to melittin (10−8 M) and insensitive to low concentrations of desmethoxyverapamil ((−)D888, 10−9–10−6 M). Depolarizing voltage steps from a holding a potential of −50 mV activated two components of the slow inward current, i.e., a slow and a sustained current (Isi(sts)) that showed a slow inactivation followed by a slow inactivation and a sustained component. Melittin at a high concentration (10−4 M) completely blocked the slow transient component (Isi(st)) and left unblocked the sustained component (Isi(s)). Both components (Isi(st) and Isi(s)) were blocked by verapamil (10−5 M) and low concentrations of (−)D888 (10−8–10−6 M).

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