Volume changes induced by osmotic stress in freshly isolated rat hippocampal neurons.

The degree to which osmotic stress changes the volume of mammalian central neurons has not previously been determined. We isolated CA1 pyramidal cells and measured cell volume in four different ways. Extracellular osmolarity (pio) was lowered by omitting varying amounts of NaCl and raised by adding mannitol; the extremes of pio tested ranged from 134 to 396 mosm/kg.

Bicuculline increases the intracellular calcium response of CA1 hippocampal neurons to synaptic stimulation.

Intracellular calcium levels were measured by ratio imaging of Fura-2-injected CA1 pyramidal neurons during repetitive electrical stimulation of the Schaffer collaterals in rat hippocampal slices. Baseline intracellular calcium levels of 102 nM increased to 190 nM during a 3-s stimulus train of 5 Hz. Bicuculline (20 microM) significantly enhanced this stimulus-dependent rise in intracellular calcium, while the baseline calcium levels remained unchanged.

Current source density of sustained potential shifts associated with electrographic seizures and with spreading depression in rat hippocampus.

The membrane currents responsible for the sustained potential shifts associated with electrographic seizures and with spreading depression in hippocampus were studied in the anesthetized rat. Probes incorporating 16 sensors in a straight line, spaced at 150-microns distances, were recording the potential changes with DC-coupled amplifiers in CA1 and dentate gyrus (DG) of one hemisphere. Seizures and spreading depression were provoked by repetitive stimulation of different afferent pathways.