G increases in the magnitude of TTX-S current in both IB
G increases in the magnitude of TTX-S current in both IB4positive and IB4-negative cells, without obvious changes in inactivation time constant or voltage dependence. Both lead to increased excitability, though these effects are larger for GRO/KC treatment. One difference is that localized inflammation led to increased TTX-R current only in IB4-positive cells, while GRO/KC incubation also increased this current in IB4-negative cells. The comparison of these two studies suggests that GRO/KC elevationsPage 12 of(page number not for citation purposes)Molecular Pain 2008, 4:http://www.molecularpain.com/content/4/1/Figure 8 (see legend on next page)Page 13 of(page number not for citation purposes)Molecular Pain 2008, 4:http://www.molecularpain.com/content/4/1/Figure sections from rat in DRG 8 (see previous detection and immunofluorescence double labelling of CXCR2 in acutely dissociated DRG neurons and Immunohistochemical page) Immunohistochemical detection and immunofluorescence double labelling of CXCR2 in acutely dissociated DRG neurons and in DRG sections from rat. A: Double staining of the dissociated DRG cells with anti-CXCR2 and antiNeuN showing that high CXCR2-expressing cells are neuronal cells, and that the more modest staining levels observed occur in almost all DRG neurons. B: Neurons with intense CXCR2 staining are all IB4-negative. C: CXCR2 staining in DRG sections showing expression on plasma membrane of most neurons, of small, medium and large diameters, with high levels expression in some smaller neurons. CXCR2 is also expressed in the nuclear membrane in some cells (arrows), as can be seen more GSK343 msds clearly in the higher magnification view in D. E: Negative control. DRG sections incubated with primary antibody preabsorbed with 30 fold excess of antigen did not show any immunoreactivity. Scale bar = 50 m. F. Western blot of protein isolated from DRG neurons, using the same antibody (1:300) as a probe. Left panel: standard. Right panel: CXCR2. in the localized inflammation model provide one plausible explanation for some, but not all of the changes in ion currents and excitability observed in this model. We observed effects on excitability and Na+ currents at a relatively low GRO/KC concentration of PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/26437915 1.5 nM, which is well within the physiological range for most peptide receptor actions. In one study, GRO/KC-stimulated (acute) Ca2+ elevation in isolated DRG neurons could be observed at GRO/KC concentrations of 6.4 nM but was not significant at 1.2 nM [19]. In cells expressing cloned CXCR2 receptors, the binding constant for GRO/KC was 0.2 nM [37]. Thus it seems plausible that the effects reported here could occur in vivo. The TTX-R currents described here, as in our previous study, had characteristics attributed to the Nav1.8 isoform. Our recording conditions would have minimized contributions from the persistent current (thought to be mediated by the Nav1.9 isoform) due to slow inactivation at the holding potentials used, and/or because the current may “washout” during whole cell patch clamp [28,38]. Other studies also suggest that the persistent current would be quite small under our recording conditions (adenosine triphosphate in the pipette, Cl- PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26100631 as the anion) [29]. In our qPCR experiments we observed that the Nav1.9 isoform was very low abundance under our culture conditions, though it had levels similar to Nav 1.8 in cDNA derived from whole DRG. Hence the lack of Nav 1.9 currents in our experiments may be related to the acute c.
