Abnormal distributions of potassium channels in human neuromas.
Twenty-seven human traumatic neuromas were examined immunocytochemically using highly specific antibodies directed against the voltage-gated delayed-rectifier potassium channel, Kv1.1. Normal sural nerves from six of the above-noted patients served as control specimens. Additionally, nine of the neuromas and two of the sural nerves were immunostained for voltage-gated calcium channels using an antibody that reacts with a wide spectrum of calcium channels. Normal myelinated fibers showed Kv1.1 specific immunoreactivity only at the juxtaparanodal regions. In contrast, within the neuromas approximately 30% of the myelinated fibers exhibited Kv1.1 specific immunoreactivity in dense patches along internodal axonal regions. The clustering of Kv1.1 channels along myelin-ensheathed internodal segments of axon was highly specific for the neuromas, and was never seen in normal nerve. Specific calcium channel immunoreactivity was not detectable in either the neuromas or sural nerves. Taken together with prior studies on sodium channels, these results suggest that selective and specific mechanisms control the distribution of ion channels within neuromas. Further investigation of ion channel changes within neuromas should provide a better understanding of the abnormal axonal hyperexcitability that frequently develops after nerve injury.
England
J D
JD
Department of Neurology, Louisiana State University School of Medicine, New Orleans 70112-2822, USA. jengla@lsumc.edu
Happel
L T
LT
Liu
Z P
ZP
Thouron
C L
CL
Kline
D G
DG
D001369:Axons / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D051662:Kv1.1 Potassium Channel; D009413:Nerve Fibers, Myelinated / Q000378:metabolism; D009463:Neuroma / Q000209:etiology / Q000378:metabolism*; D059348:Peripheral Nerve Injuries; D010524:Peripheral Nervous System Neoplasms / Q000209:etiology / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D012016:Reference Values; D013497:Sural Nerve / Q000378:metabolism; D014018:Tissue Distribution; D014947:Wounds and Injuries / Q000150:complications
C496946:KCNA1 protein, human; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051662:Kv1.1 Potassium Channel