Abstract
Voltage-activated Na + channels in the primary sensory neurons are important for generation of action potentials and regulation of neurotransmitter release. The Na + channels expressed in different types of dorsal root ganglion (DRG) neurons are not fully known. In this study, we determined the possible difference in tetrodotoxin-sensitive (TTX-S) and -resistant (TTX-R) Na + channel currents between isolectin B4 (IB 4)-positive and IB 4-negative small DRG neurons. Whole-cell voltage- and current-clamp recordings were performed in acutely isolated DRG neurons labeled with and without IB 4 conjugated to Alexa Fluor 594. The peak Na + current density was significantly higher in IB 4-negative than IB 4-positive DRG neurons. While all the IB 4-negative neurons had a prominent TTX-S Na + current, the TTX-R Na + current was present in most IB 4-positive cells. Additionally, the evoked action potential had a higher activation threshold and a longer duration in IB 4-positive than IB 4-negative neurons. TTX had no effect on the evoked action potential in IB 4-positive neurons, but it inhibited the action potential generation in about 50% IB 4-negative neurons. This study provides complementary new information that there is a distinct difference in the expression level of TTX-S and TTX-R Na + channels between IB 4-negative than IB 4-positive small-diameter DRG neurons. This difference in the density of TTX-R Na + channels is responsible for the distinct membrane properties of these two types of nociceptive neurons.
Original language | English (US) |
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Pages (from-to) | 251-258 |
Number of pages | 8 |
Journal | Brain Research |
Volume | 1029 |
Issue number | 2 |
DOIs | |
State | Published - Dec 17 2004 |
Externally published | Yes |
Keywords
- Dorsal root ganglia
- Neurotrophin
- Nociceptor
- Sodium channel
ASJC Scopus subject areas
- Neuroscience(all)
- Molecular Biology
- Clinical Neurology
- Developmental Biology