NaV1.8 channels are expressed in large, as well as small, diameter sensory afferent neurons.
Sensory neurons in the dorsal root ganglia (DRG) express a subset of voltage dependent sodium channels (NaV) including NaV1.1, 1.6, 1.7, 1.8 and 1.9. Previous work supported preferential localization of NaV1.8 channels to small-medium diameter, nociceptive afferent neurons. However, we recently published evidence that NaV1.8 was the dominant NaV channel expressed in the somas of small, medium and large diameter muscle afferent neurons, which is consistent with other reports. Here, we extend those results to show that NaV1.8 expression is not correlated with afferent neuron diameter. Using immunocytochemistry, we found NaV1.8 expression in ~50% of sensory afferent neurons with diameters ranging from 20 to 70 µm. In addition, electrophysiological analysis shows that the kinetic and inactivation properties of NaV1.8 current are invariant with neuron size. These data add further support to the idea that NaV1.8 contributes to the electrical excitability of both nociceptive and non-nociceptive sensory neurons.
The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, AT Still University of Health Sciences, Kirksville, MO, USA.
Renuka
R
Ramachandra
Stephanie Y
SY
McGrew
James C
JC
Baxter
Jason R
JR
Howard
Keith S
KS
Elmslie
D000818:Animals; D048429:Cell Size; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D008297:Male; D062559:NAV1.8 Voltage-Gated Sodium Channel / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000166:cytology* / Q000378:metabolism*
D062559:NAV1.8 Voltage-Gated Sodium Channel; C568319:Scn10a protein, rat