1. Calcium dependence of axotomized sensory neurons excitability.
- Author
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Hilaire C, Inquimbert P, Al-Jumaily M, Greuet D, Valmier J, and Scamps F
- Subjects
- Action Potentials physiology, Animals, Axotomy, Buffers, Calcium metabolism, Cell Size, Disease Models, Animal, Electric Impedance, Female, Ganglia, Spinal physiopathology, Homeostasis physiology, Intracellular Fluid metabolism, Mice, Neuralgia physiopathology, Neurons, Afferent pathology, Patch-Clamp Techniques, Peripheral Nervous System Diseases physiopathology, Sciatic Nerve metabolism, Sciatic Nerve physiopathology, Sciatic Neuropathy physiopathology, Calcium Signaling physiology, Ganglia, Spinal metabolism, Neuralgia metabolism, Neurons, Afferent metabolism, Peripheral Nervous System Diseases metabolism, Sciatic Neuropathy metabolism
- Abstract
Hyperexcitability of axotomized dorsal root ganglion neurons is thought to play a role in neuropathic pain. Numerous changes in ionic channels expression or current amplitude are reported after an axotomy, but to date no direct correlation between excitability of axotomized sensory neurons and ionic channels alteration has been provided. Following sciatic nerve injury, we examined, under whole-cell patch clamp recording, the effects of calcium homeostasis on the electrical activity of axotomized medium-sized sensory neurons isolated from lumbar dorsal root ganglia of adult mice. Axotomy induced an increase in excitability of medium sensory neurons among which 25% develop a propensity to fire repetitively. The condition necessary to get burst discharge in axotomized neurons was the presence of a high intracellular Ca2+ buffer concentration. The main effect was to amplify the increase in threshold current and apparent input resistance induced by axotomy. These data supply evidence for a role of Ca2+-dependent mechanisms in the control of excitability of axotomized sensory neurons.
- Published
- 2005
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