NO donor activates primary cultured DRG neurons.

<p>(A, B) Responses of primary cultured DRG neurons assessed by ratiometric calcium imaging. Fluorescent ratios (F340/F380) of individual neurons (A) and averaged traces (B) are shown. Fast-SNAP+ neurons display significantly increased intracellular calcium upon NO donor application within one minute (blue traces), and slow-SNAP+ neurons after one minute (red traces). Neurons without significant increases in intracellular calcium are also shown (B, green trace). Proportions of fast- and slow-SNAP+ in (B) are shown as percentages. DRG neurons were challenged with SNAP (3 mM) for 5 min (green bar). Capsaicin (Caps, 10 µM, red bar) was applied at the end as a control. (C) Summary of responses of primary cultured DRG neurons assessed by ratiometric calcium imaging. Proportions of neurons activated by SNAP (three left columns; subdivided into fast-SNAP+ (blue) and slow-SNAP+ (red) responders), and pCPT-cGMP (2 mM) and NAP (3 mM; non-NO releasing isomer of SNAP) (two right black columns) are shown. SNAP induced intracellular calcium responses were sensitive to Ruthenium red (“with RR”) and required extracellular calcium (“0 Ca(ext)”). Cells were exposed to RR (10 µM) and calcium depleted saline 3 min prior to and throughout SNAP application and washed out prior to capsaicin addition. The proportion responsive to capsaicin was normal in these experiments.