Korean J Pain.  2007 Dec;20(2):92-99. 10.3344/kjp.2007.20.2.92.

Antihyperalgesic Effects of Ethosuximide and Mibefradil, T-type Voltage Activated Calcium Channel Blockers, in a Rat Model of Postoperative Pain

• Shinn HK
• Cha YD
• Han JU
• Yoon JW
• Kim BS
• Song JH

• KMID: 2278047
• DOI: http://doi.org/10.3344/kjp.2007.20.2.92

Abstract

BACKGROUND: A correlation between a T-type voltage activated calcium channel (VACC) and pain mechanism has not yet been established. The purpose of this study is to find out the effect of ethosuximide and mibefradil, representative selective T-type VACC blockers on postoperative pain using an incisional pain model of rats.
METHODS
After performing a plantar incision, rats were stabilized on plastic mesh for 2 hours. Then, the rats were injected with ethosuximide or mibefradil, intraperitoneally and intrathecally. The level of withdrawal threshold to the von Frey filament near the incision site was determined and the dose response curves were obtained.
RESULTS
After an intraperitoneal ethosuximide or mibefradil injection, the dose-response curve showed a dose-dependent increase of the threshold in a withdrawal reaction. After an intrathecal injection of ethosuximide, the threshold of a withdrawal reaction to mechanical stimulation increased and the increase was dose-dependent. After an intrathecal injection of mibefradil, no change occurred in either the threshold of a withdrawal reaction to mechanical stimulation or a dose-response curve.
CONCLUSIONS
The T-type VACC blockers in a rat model of postoperative pain showed the antihyperalgesic effect. This effect might be due to blockade of T-type VACC, which was distributed in the peripheral nociceptors or at the supraspinal level. Further studies of the effect of T-type VACC on a pain transmission mechanism at the spinal cord level would be needed.

Keyword

ethosuximide; incisional pain model; mibefradil; voltage activated calcium channel

MeSH Terms

Animals
Calcium Channel Blockers*
Calcium Channels*
Calcium*
Ethosuximide*
Injections, Spinal
Mibefradil*
Models, Animal*
Nociceptors
Pain, Postoperative*
Plastics
Rats*
Spinal Cord
Calcium
Calcium Channel Blockers
Calcium Channels
Ethosuximide
Mibefradil
Plastics