Toxicol Appl Pharmacol
December 2013
We hypothesized that circulating microparticles (MPs) play a role in pro-inflammatory effects associated with carbon monoxide (CO) inhalation. Mice exposed for 1h to 100 ppm CO or more exhibit increases in circulating MPs derived from a variety of vascular cells as well as neutrophil activation. Tissue injury was quantified as 2000 kDa dextran leakage from vessels and as neutrophil sequestration in the brain and skeletal muscle; and central nervous system nerve dysfunction was documented as broadening of the neurohypophysial action potential (AP).
View Article and Find Full Text PDFThe study goal was to use membrane voltage changes during neurohypophysial action potential (AP) propagation as an index of nerve function to evaluate the role that circulating microparticles (MPs) play in causing central nervous system injury in response to decompression stress in a murine model. Mice studied 1 h following decompression from 790 kPa air pressure for 2 h exhibit a 45% broadening of the neurohypophysial AP. Broadening did not occur if mice were injected with the MP lytic agent polyethylene glycol telomere B immediately after decompression, were rendered thrombocytopenic, or were treated with an inhibitor of nitric oxide synthase-2 (iNOS) prior to decompression, or in knockout (KO) mice lacking myeloperoxidase or iNOS.
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December 2012
Intrinsic optical changes (light scattering signals) occur in mammalian nerve terminals during and immediately following the arrival of the action potential. In the neurohypophysis (posterior pituitary gland), the action potential is coupled to calcium-mediated secretion of the neuropeptides oxytocin and vasopressin. This excitation-secretion coupling is intimately related to extremely rapid changes in light scattering.
View Article and Find Full Text PDFWe report the first optical recordings of action potentials, in single trials, from one or a few (approximately 1-2 microm) mammalian nerve terminals in an intact in vitro preparation, the mouse neurohypophysis. The measurements used two-photon excitation along the "blue" edge of the two-photon absorption spectrum of di-3-ANEPPDHQ (a fluorescent voltage-sensitive naphthyl styryl-pyridinium dye), and epifluorescence detection, a configuration that is critical for noninvasive recording of electrical activity from intact brains. Single-trial recordings of action potentials exhibited signal-to-noise ratios of approximately 5:1 and fractional fluorescence changes of up to approximately 10%.
View Article and Find Full Text PDFThe toxicity of arsenic (As) species to Lemna gibba L. and the influence of PO(4) (3-) on As bioavailability and uptake were tested in batch culture. L.
View Article and Find Full Text PDFUsing millisecond time-resolved optical recordings of transmembrane voltage and intraterminal calcium, we have determined how activity-dependent changes in the population action potential are related to a concurrent modulation of calcium transients in the neurohypophysis. We find that repetitive stimulation dramatically alters the amplitude of the population action potential and significantly increases its temporal dispersion. The population action potentials and the calcium transients exhibit well correlated frequency-dependent amplitude depression, with broadening of the action potential playing only a limited role.
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