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Vanilloid-sensitive afferents activate neurons with prominent A-type potassium currents in nucleus tractus solitarius.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bailey, Timothy W. Jin, Yan Doyle, Mark W. Andresen, Michael C. |
| Copyright Year | 2002 |
| Abstract | Cranial visceral afferents innervate second-order nucleus tractus solitarius (NTS) neurons via myelinated (A-type) and unmyelinated (C-type) axons in the solitary tract (ST). A- and C-type afferents often evoke reflexes with distinct performance differences, especially with regard to their frequency-dependent properties. In horizontal brainstem slices, we used the vanilloid receptor 1 agonist capsaicin (CAP; 100 nm) to identify CAP-sensitive and CAP-resistant ST afferent pathways to second-order NTS neurons and tested whether these two groups of neurons had similar intrinsic potassium currents. ST stimulation evoked monosynaptic EPSCs identified by minimal synaptic jitter (<150 microsec) and divided into two groups: CAP-sensitive (n = 37) and CAP-resistant (n = 22). EPSCs in CAP-sensitive neurons had longer latencies (5.1 +/- 0.3 vs 3.6 +/- 0.3 msec; p = 0.001) but similar jitter (p = 0.57) compared with CAP-resistant neurons, respectively. Transient outward currents (TOCs) were significantly greater in CAP-sensitive than in CAP-resistant neurons. Steady-state currents were similar in both groups. 4-Aminopyridine or depolarized conditioning blocked the TOC, but tetraethylammonium had no effect. Voltage-dependent activation and inactivation of TOC were consistent with an A-type K+ current, I(KA). In current clamp, the activation of I(KA) reduced neuronal excitability and action potential responses to ST transmission. Our results suggest that the potassium-channel differences of second-order NTS neurons contribute to the differential processing of A- and C-type cranial visceral afferents beginning as early as this first central neuron. I(KA) can act as a frequency transmission filter and may represent a key target for the modulation of temporal processing of reflex responsiveness such as within the baroreflex arc. |
| Starting Page | 2642 |
| Ending Page | 2646 |
| Page Count | 5 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.jneurosci.org/content/jneuro/22/18/8230.full.pdf |
| PubMed reference number | 12223577v1 |
| Volume Number | 22 |
| Issue Number | 18 |
| Journal | The Journal of neuroscience : the official journal of the Society for Neuroscience |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Activation action Afferent Pathways Axon Baroreflex Brain Stem Ischemia, Transient Capsaicin Cell Nucleus Central neuron Conditioning (Psychology) Myelin Sheath Neurons Potassium Reflex action Reflex, Monosynaptic Solitary tract TRPV Cation Channels TYLOSIS WITH ESOPHAGEAL CANCER Tetraethylammonium Vanilloid Visceral Afferents dalfampridine |
| Content Type | Text |
| Resource Type | Article |
