The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
M D Wang - One of the best experts on this subject based on the ideXlab platform.
-
The functional role of a Bicuculline-sensitive Ca2+-activated K+ current in rat medial preoptic neurons.
The Journal of physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
-
The functional role of a Bicuculline‐sensitive Ca2+‐activated K+ current in rat medial preoptic neurons
The Journal of Physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
S Johansson - One of the best experts on this subject based on the ideXlab platform.
-
Bicuculline free base blocks voltage-activated K+ currents in rat medial preoptic neurons
Neuropharmacology, 2004Co-Authors: M Druzin, D Haage, S JohanssonAbstract:The effects of the well-known GABA(A)-receptor blocker Bicuculline on voltage-gated K(+) currents were studied in neurons from the medial preoptic nucleus (MPN) of rat. Whole-cell currents were recorded using the perforated-patch technique. Voltage steps from -54 to +6 mV resulted in tetraethylammonium-sensitive K(+) currents of delayed rectifier type. The total K(+) current (at 300 ms), including Ca(2+)-dependent and Ca(2+)-independent components, was reversibly reduced (17 +/- 4%) by 100 microM Bicuculline Methiodide and (37 +/- 5%) by 100 microM Bicuculline as free base. The Ca(2+)-independent fraction (77 +/- 2%) of K(+) current evoked by a voltage step was, however, reduced (54 +/- 6%) only by Bicuculline free base, but was not affected by Bicuculline Methiodide. The half-saturating concentration of Bicuculline free base for blocking this purely voltage-gated K(+) current was 113 microM, whereas for blocking a steady Ca(2+)-dependent K(+) current it was 36 microM. The Bicuculline-sensitive voltage-gated K(+) current was composed of 4-AP-sensitive and 4-AP-resistant components with different kinetic properties. No component of the purely voltage-gated K(+) current was affected neither by 100 nM alpha-dendrotoxin nor by 100 nM I-dendrotoxin. The possible K(+)-channel subtypes mediating the Bicuculline-sensitive current in MPN neurons are discussed.
-
The functional role of a Bicuculline-sensitive Ca2+-activated K+ current in rat medial preoptic neurons.
The Journal of physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
-
The functional role of a Bicuculline‐sensitive Ca2+‐activated K+ current in rat medial preoptic neurons
The Journal of Physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
M Druzin - One of the best experts on this subject based on the ideXlab platform.
-
Bicuculline free base blocks voltage-activated K+ currents in rat medial preoptic neurons
Neuropharmacology, 2004Co-Authors: M Druzin, D Haage, S JohanssonAbstract:The effects of the well-known GABA(A)-receptor blocker Bicuculline on voltage-gated K(+) currents were studied in neurons from the medial preoptic nucleus (MPN) of rat. Whole-cell currents were recorded using the perforated-patch technique. Voltage steps from -54 to +6 mV resulted in tetraethylammonium-sensitive K(+) currents of delayed rectifier type. The total K(+) current (at 300 ms), including Ca(2+)-dependent and Ca(2+)-independent components, was reversibly reduced (17 +/- 4%) by 100 microM Bicuculline Methiodide and (37 +/- 5%) by 100 microM Bicuculline as free base. The Ca(2+)-independent fraction (77 +/- 2%) of K(+) current evoked by a voltage step was, however, reduced (54 +/- 6%) only by Bicuculline free base, but was not affected by Bicuculline Methiodide. The half-saturating concentration of Bicuculline free base for blocking this purely voltage-gated K(+) current was 113 microM, whereas for blocking a steady Ca(2+)-dependent K(+) current it was 36 microM. The Bicuculline-sensitive voltage-gated K(+) current was composed of 4-AP-sensitive and 4-AP-resistant components with different kinetic properties. No component of the purely voltage-gated K(+) current was affected neither by 100 nM alpha-dendrotoxin nor by 100 nM I-dendrotoxin. The possible K(+)-channel subtypes mediating the Bicuculline-sensitive current in MPN neurons are discussed.
-
The functional role of a Bicuculline-sensitive Ca2+-activated K+ current in rat medial preoptic neurons.
The Journal of physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
-
The functional role of a Bicuculline‐sensitive Ca2+‐activated K+ current in rat medial preoptic neurons
The Journal of Physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
D Haage - One of the best experts on this subject based on the ideXlab platform.
-
Bicuculline free base blocks voltage-activated K+ currents in rat medial preoptic neurons
Neuropharmacology, 2004Co-Authors: M Druzin, D Haage, S JohanssonAbstract:The effects of the well-known GABA(A)-receptor blocker Bicuculline on voltage-gated K(+) currents were studied in neurons from the medial preoptic nucleus (MPN) of rat. Whole-cell currents were recorded using the perforated-patch technique. Voltage steps from -54 to +6 mV resulted in tetraethylammonium-sensitive K(+) currents of delayed rectifier type. The total K(+) current (at 300 ms), including Ca(2+)-dependent and Ca(2+)-independent components, was reversibly reduced (17 +/- 4%) by 100 microM Bicuculline Methiodide and (37 +/- 5%) by 100 microM Bicuculline as free base. The Ca(2+)-independent fraction (77 +/- 2%) of K(+) current evoked by a voltage step was, however, reduced (54 +/- 6%) only by Bicuculline free base, but was not affected by Bicuculline Methiodide. The half-saturating concentration of Bicuculline free base for blocking this purely voltage-gated K(+) current was 113 microM, whereas for blocking a steady Ca(2+)-dependent K(+) current it was 36 microM. The Bicuculline-sensitive voltage-gated K(+) current was composed of 4-AP-sensitive and 4-AP-resistant components with different kinetic properties. No component of the purely voltage-gated K(+) current was affected neither by 100 nM alpha-dendrotoxin nor by 100 nM I-dendrotoxin. The possible K(+)-channel subtypes mediating the Bicuculline-sensitive current in MPN neurons are discussed.
-
The functional role of a Bicuculline-sensitive Ca2+-activated K+ current in rat medial preoptic neurons.
The Journal of physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
-
The functional role of a Bicuculline‐sensitive Ca2+‐activated K+ current in rat medial preoptic neurons
The Journal of Physiology, 2001Co-Authors: S Johansson, M Druzin, D Haage, M D WangAbstract:A Ca2+-activated K+ current was identified in neurons from the rat medial preoptic nucleus. Its functional role for the resting potential and for impulse generation was characterised by using the reversible blocking agent Bicuculline Methiodide. Acutely dissociated neurons were studied by perforated-patch recordings. The effect of Bicuculline Methiodide was investigated under voltage-clamp conditions to clearly identify the current affected. At membrane potentials > -50 mV, Bicuculline Methiodide rapidly (< 1 s) and reversibly blocked a steady outward current. Half-saturating concentration was 12 microM. The current amplitude increased with potential in the range -50 to 0 mV. The Bicuculline-sensitive current was identified as an apamin-sensitive, Ca2+-dependent K+ current. It was neither affected by the GABAA receptor blocker picrotoxin (100 microM) nor by a changed pipette Cl- concentration, but was affected by substitution of extracellular K+ for Na+. The current was dependent on extracellular Ca2+ and was sensitive to 1 microM apamin but not to 200 nM charybdotoxin. A role for the Ca2+-dependent K+ current in setting the resting potential and controlling spontaneous firing frequency was observed under current-clamp conditions. Bicuculline Methiodide (100 microM) induced a positive shift (5 +/- 1 mV; n = 18) of resting potential in all neurons tested. In the majority of spontaneously firing neurons, the firing frequency was reversibly affected, either increased or decreased depending on the cell, by Bicuculline Methiodide.
Daniel J Simons - One of the best experts on this subject based on the ideXlab platform.
-
laminar differences in Bicuculline Methiodide s effects on cortical neurons in the rat whisker barrel system
Somatosensory and Motor Research, 1998Co-Authors: Harold T Kyriazi, George E Carvell, Joshua C Brumberg, Daniel J SimonsAbstract:Extracellular unit recordings were made at various depths within SmI barrel cortex of immobilized, sedated rats, in the presence and absence of titrated amounts of the GABAA receptor antagonist Bicuculline Methiodide (BMI). Principal and adjacent whiskers were moved singly, or in paired combination in a condition-test paradigm, to assess excitatory and inhibitory receptive field (RF) characteristics. Neurons were classified as regular- or fast-spike units, and divided into three laminar groups: supragranular, granular (barrel), and infragranular. BMI increased response magnitude and duration, but did not affect response latencies. The excitatory RFs of barrel units, which are the most tightly focused on the principal whisker, were the most greatly defocused by BMI; infragranular units were least affected. All three layers had approximately equal amounts of adjacent whisker-evoked, surround inhibition, but BMI counteracted this inhibition substantially in barrel units and less so in infragranular units. Th...
-
Quantitative effects of GABA and Bicuculline Methiodide on receptive field properties of neurons in real and simulated whisker barrels
Journal of neurophysiology, 1996Co-Authors: Harold T Kyriazi, George E Carvell, Joshua C Brumberg, Daniel J SimonsAbstract:1. Carbon fiber multibarrel glass microelectrodes were used to record extracellular single-unit activity during microiontophoretic application of gamma-aminobutyric acid (GABA) or Bicuculline Methiodide (BMI) onto layer IV barrel neurons in the somatosensory cortex of fentanyl-sedated rats. Excitatory and inhibitory aspects of the neurons' receptive fields were quantified with the use of controlled whisker stimuli. The principally activating whisker and one of its immediately adjacent neighbors were deflected alone or in paired combinations involving a condition-test paradigm. 2. Units were distinguished electrophysiologically on the basis of the time course of their action potential waveforms. Data were obtained from 26 regular-spike units (RSUs; presumed spiny stellate cells) and 7 fast-spike units (FSUs; presumed GABAergic neurons). An average of 15.0 nA of GABA produced a one-third to one-half reduction in RSU responses evoked by the maximally effective stimulus. An average of 8.7 nA of BMI was needed to counteract this reduction. This amount of BMI, in the absence of exogenous GABA, was found to increase average RSU and FSU responses by 98 and 53%, respectively, relative to predrug levels. 3. For RSUs, the BMI-induced twofold increase in responses evoked by moving the principal whisker at the neuron's best deflection angle was accompanied by an almost threefold increase in responses evoked by similarly moving an adjacent whisker. Disproportionately large percentage increases were also seen for responses to nonpreferred directions of principal and adjacent whisker movement. BMI thus effectively increased receptive field size and decreased angular tuning. Similarly, responses to stimulus offsets, which are normally smaller than ON responses, were increased proportionally more. 4. Predrug responses of FSUs were more vigorous than those of RSUs. However, FSUs showed a similar inverse relationship between percentage increase with BMI and initial response magnitude, although the proportional increases were less pronounced. 5. GABA, like BMI, had the greatest proportional effects on those responses that were initially smallest. It produced results opposite those of BMI, effectively decreasing receptive field size and sharpening angular tuning. 6. A previously described computational model of a barrel was tested for its ability to reproduce quantitatively the effects of BMI and GABA. The application of BMI was simulated by decreasing the strength of the inhibitory inputs onto the particular cell under study in the model network. GABA microiontophoresis was simulated by adding a constant hyperpolarizing voltage. The model RSUs and FSUs displayed proportional changes in response magnitude that were quantitatively similar to those of their biological counterparts. 7. Surround inhibition was greatly attenuated by BMI application, both for the real and simulated barrel neurons. Disinhibition was less pronounced for the former, perhaps because, unlike the simulated neurons, they also possess GABAB receptors, which are unaffected by BMI. 8. We conclude that the inhibitory receptive field properties of barrel neurons can be explained by intrabarrel inhibition and that the expansion of receptive field size and loss of angular tuning with BMI is due to an enhanced effectiveness of convergent, multi-whisker thalamocortical input. Examination of the model neurons' behavior suggests that the altered activity in response to GABA or BMI application, respectively, can be explained by the nonlinear effects of shifting somal membrane potential away from or toward the neuron's firing threshold.