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Voltage-gated calcium currents in axotomized adult rat cutaneous afferent neurons.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Baccei, Mark L. Kocsis, Jeffery D. |
| Copyright Year | 2000 |
| Abstract | The effect of sciatic nerve injury on the somatic expression of voltage-gated calcium currents in adult rat cutaneous afferent dorsal root ganglion (DRG) neurons identified via retrograde Fluoro-gold labeling was studied using whole cell patch-clamp techniques. Two weeks after a unilateral ligation and transection of the sciatic nerve, the L(4)-L(5) DRG were dissociated and barium currents were recorded from cells 3-10 h later. Cutaneous afferents (35-50 microm diam) were classified as type 1 (possessing only high-voltage-activated currents; HVA) or type 2 (having both high- and low-voltage-activated currents). Axotomy did not change the percentage of neurons exhibiting a type 2 phenotype or the properties of low-threshold T-type current found in type 2 neurons. However, in type 1 neurons the peak density of HVA current available at a holding potential of -60 mV was reduced in axotomized neurons (83.9 +/- 5.6 pA/pF, n = 53) as compared with control cells (108.7 +/- 6.9 pA/pF, n = 58, P < 0.01, unpaired t-test). A similar reduction was observed at more negative holding potentials, suggesting differences in steady-state inactivation are not responsible for the effect. Separation of the type 1 cells into different size classes indicates that the reduction in voltage-gated barium current occurs selectively in the larger (capacitance >80 pF) cutaneous afferents (control: 112.4 +/- 10.6 pA/pF, n = 30; ligated: 72.6 +/- 5.0 pA/pF, n = 36; P < 0.001); no change was observed in cells with capacitances of 45-80 pF. Isolation of the N- and P¿Q-type components of the HVA current in the large neurons using omega-conotoxin GVIA and omega-agatoxin TK suggests a selective reduction in N-type barium current after nerve injury, as the density of omega-CgTx GVIA-sensitive current decreased from 56.9 +/- 6.6 pA/pF in control cells (n = 13) to 31.3 +/- 4.6 pA/pF in the ligated group (n = 12; P < 0.005). The HVA barium current of large cutaneous afferents also demonstrates a depolarizing shift in the voltage dependence of inactivation after axotomy. Injured type 1 cells exhibited faster inactivation kinetics than control neurons, although the rate of recovery from inactivation was similar in the two groups. The present results indicate that nerve injury leads to a reorganization of the HVA calcium current properties in a subset of cutaneous afferent neurons. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://jn.physiology.org/content/jn/83/4/2227.full.pdf |
| PubMed reference number | 10758131v1 |
| Volume Number | 83 |
| Issue Number | 4 |
| Journal | Journal of neurophysiology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Afferent neuron Axotomy Barium Sulfate Calcium Class Classification Conotoxin Cutaneous Candidiasis Diameter (qualifier value) Diploid Cell Eighty Electric Capacitance Exhibits as Topic Ganglia, Spinal Homovanillic Acid Large Ligation Patch-Clamp Techniques Structure of sciatic nerve Subgroup Trichophyton reaction wheal^3D post 50 ug trichophyton ID:Diam:Pt:Skin:Qn omega-Conotoxin GVIA omega-Conotoxins sciatic nerve injury t test voltage |
| Content Type | Text |
| Resource Type | Article |
