Compound 52 reduced the ongoing spontaneous activity of C-fiber nociceptors but not Aδ-fiber nociceptors.

<p>Intravenous injection of compound 52 decreased ongoing spontaneous activity of C-fiber nociceptors sensitized by intraplantar administration of CFA (upper panel). The level of ongoing spontaneous activity of sensitized C-fiber nociceptors was significantly lower following administration of compound 52 than following administration of vehicle, from 12 minutes post-administration on. The attenuation of ongoing spontaneous activity by compound 52 continued until the end of the monitoring period (26 minutes after administration of drug). In contrast, administration of compound 52 did not decrease the level of ongoing spontaneous activity in Aδ-fiber nociceptors when compared to vehicle (lower panel). *p < 0.05; **p < 0.01.