| The Effects of Intravenous Anesthetics on Formalin Test in Rats. |
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Hae Kyu Kim, Seunghee Yi, Jae Young Kwon, Inn Se Kim, Sang Wook Shin |
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Department of Anesthesiology, College of Medicine, Pusan National University, Pusan, Korea. |
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| Abstract |
BACKGROUND
Subcutaneous injection of 5% formalin in the hind paw of the rat produces a biphasic nociceptive response. The second phase depends on changes in dorsal horn cell function that occur shortly after the initial C-fiber discharge, spinal sensitization, or windup phenomenon.
Several studies about the effect of analgesic or anesthetic drugs on spinal sensitization has been done and we studied the effects of common intravenous anesthetic agents, thiopental, propofol and ketamine on spinal sensitization.
METHODS
Sprague-Dawley rats weighing 200 to 250 gm were used for this study. Under halothane anesthesia PE-10 catheter was introduced into the right internal jugular vein, and tunnelled subcutaneously to the back of the rat.
Before formalin test, animals were given saline 0.2 ml, propofol 10 mg/kg, propofol 6 mg/kg, thiopental 15 mg/kg, or ketamine 15 mg/kg. After formalin injection flinching was counted for 90 minutes.
RESULTS
Propofol caused a significant decrease in phase 2 activity while thiopental showed no difference compared to control. Ketamine also caused a significant decrease in phase 2 activity.
CONCLUSIONS
Propofol and ketamine not thiopental alter the spinal sensitization in rats. So we consider that these agents may have beneficial effect on attenuation of postoperative pain. |
| Key Words:
Animal; rats; Anesthetics; intravenous; ketamine; propofol; thiopental; Pain; experimental; formalin test |
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