Figure 5.

Ongoing activity and expression of pacemaker channels HCN1–3 in iDNs. (A–C) Immunoreactivity of HCN1–3 was reproducibly detected both in iDNs and mDRG neurons (arrowheads). 100% of cells showed immunoreactivity of HCN1–3 based on DAPI counterstaining, respectively; (D) HCN4 was not expressed in D26 iDNs or in mDRG controls, scale bar 40 µm; (E) iDNs exhibit a low baseline Ca²⁺ concentration but regular transient increases (ratio F340/F380) indicative of spontaneous discharge activity (n = 30). Pie chart indicating the percentage of spontaneously active iDNs (70%) as compared with inactive iDNs (30%) at D60.