Heterogeneous expression of the voltage-gated calcium channel α2 subunit and the voltage-gated sodium channel α subunit in chicken spinal motoneurons

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The localization of the voltage-gated calcium channel (VGCC) α2 and the voltage-gated sodium channel (VGSC) α subunits was immunohistochemically investigated in chicken spinal motoneurons. Approximately 83% and 46% of spinal motoneurons were positive for VGCCα2 and VGSCα subunits, respectively. Almost all VGSCα subunit-positive motoneurons exhibited the VGCCα2 subunit immunoreactivity. There were different patterns in occurrence, intensity or nuclear/cytoplasmic stainability of the VGCCα2 and VGSCα subunits among the motoneurons. This study presents the first cellular morphological evidence for the VGCCα2 and VGSCα subunits in spinal motoneurons, postulating that the heterogeneous expression of VGCCα2 and VGSCα subunits in the motoneurons may reflect various motor activities.