engleski

Restoration of Calcium Influx Corrects Membrane Hyperexcitability in Injured Rat Dorsal Root Ganglion Neurons

Background: We have previously shown that a decrease of inward Ca2+ flux (I-Ca) across the sensory neuron plasmalemma, such as happens after axotomy, increases neuronal excitability. From this, we predicted that increasing I-Ca in injured neurons should correct their hyperexcitability. Methods: The influence of increased or decreased I-Ca upon membrane biophysical variables and excitability was determined during recording from A-type neurons in nondissociated dorsal root ganglia after spinal nerve ligation using an, intracellular recording technique. Results: When the bath Ca2+ level was increased to promote I-Ca, the after-hyperpolarization was decreased and repetitive firing was suppressed, which also followed amplification of Ca2+-activated K+ current with selective agents NS1619 and NS309. A decreased external bath Ca2+ concentration had the opposite effects, similar to previous observations in uninjured neurons. Conclusions: These findings indicate that at least a part of the hyperexcitability of somatic sensory neurons after axotomy is attributable to diminished inward Ca2+ flux, and that measures to restore I-Ca may potentially be therapeutic for painful peripheral neuropathy.

Spinal nerve ligation ; Primary afferent neurons ; Autotomy-induced changes ; Sensory neurons ; K+ channels ; N-type. Potassium currents ; Neuropathic pain ; Excitability ; Activation

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