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Extracellular potassium concentration, [K(+)](o), and intracellular calcium, [Ca(2+)](i), rise during neuron excitation, seizures and spreading depression. Astrocytes probably restrain the rise of K(+) in a way that is only partly understood. To examine the effect of glial K(+) uptake, we used a model neuron equipped with Na(+), K(+), Ca(2+) and Cl(-)(More)
1. Neurones were isolated from the hippocampus of adult guinea-pigs by enzymatic and mechanical treatment. The electrophysiological properties of these cells were examined immediately after dissociation by intracellular recordings using low-resistance electrodes (2-5 M omega). 2. Pyramidal-shaped cells were identified visually. Intracellular recordings(More)
As described by others, an extracellular calcium-sensitive non-selective cation channel ([Ca(2+)](o)-sensitive NSCC) of central neurons opens when extracellular calcium level decreases. An other non-selective current is activated by rising intracellular calcium ([Ca(2+)]( i )). The [Ca(2+)](o)-sensitive NSCC is not dependent on voltage and while it is(More)
To explore non-synaptic mechanisms in paroxysmal discharges, we used a computer model of a simplified hippocampal pyramidal cell, surrounded by interstitial space and a "glial-endothelial" buffer system. Ion channels for Na+, K+, Ca2+ and Cl- ion antiport 3Na/Ca, and "active" ion pumps were represented in the neuron membrane. The glia had "leak"(More)
High voltage activated (HVA) and low voltage activated (LVA) calcium currents were recorded in acutely dissociated CA1 hippocampal pyramidal neurons of the rat during the first three postnatal weeks as well as in adults. Measured in whole cell voltage clamp the amplitude of the HVA calcium current increased steadily and reached adult values after 20(More)
Spatially resolved measurements of intracellular free calcium and of the changes produced by excitatory amino acids were made in neurons isolated from adult mammalian brain. Extremely long-lasting (minutes) Ca2+ gradients were induced in the apical dendrites of hippocampal CA1 neurons after brief (1 to 3 seconds), local application of either glutamate or(More)
Spatiotemporal changes of the intracellular calcium ion (Ca2+) were recorded by digital ratio imaging of fura-2 in pyramidal neurons acutely isolated from the adult guinea-pig hippocampus. Increases in calcium were evoked in tetrodotoxin (2 microM) containing saline either by stimulation with the excitatory amino acids, glutamate or N-methyl-D-aspartate, or(More)
Whole-cell voltage clamp techniques were used to characterize sustained outward currents in maturing (P4 to P48) acutely isolated rat CA1 hippocampal neurones. Sodium removal and signal subtraction were used to isolate a sodium dependent sustained potassium current (IKNa). Calcium blockade (Co2+), sensitivity to a low TEA dose (0.5 mM) and sensitivity to(More)
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