Mechanical and thermal anti-nociception in rats after systemic administration of verapamil

Voltage-gated Ca(2+) channels expressed in neurons may contribute to nociceptive information processing. However, the role of L-type Ca(2+) channels in pain transmission is not well understood. In this study, we examined the effects of systemically administered verapamil, an antihypertensive agent and L-type Ca(2+) channel blocker, on mechanical and thermal withdrawal thresholds in rats. Intraperitoneal injections of verapamil induced dose-dependent (3-18 mg/kg) mechanical and thermal anti-nociception in adult rats without altering their sensorimotor abilities. Our data suggest that L-type Ca(2+) channels contribute to acute nociceptive signaling and that anti-nociceptive effects may result from the blockade of these channels.