2003 Fiscal Year Final Research Report Summary
Anesthetic mechanisms and surgical injury
| Project/Area Number |
13470325
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Anesthesiology/Resuscitation studies
|
|---|
| Research Institution | Sapporo Med.Univ.Sch.of Med. |
|---|
Principal Investigator |
NAMIKI Akiyoshi Sapporo Med.Univ., Sch.of Med., Professor, 医学部, 教授 (00136954)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAWAMATA Mikito Sapporo Med.Univ., Sch.of Med., Assistant Professor, 医学部, 講師 (90315523)
|
|---|
| Project Period (FY) |
2001 – 2003
|
| Keywords | anesthetics / surgical injury / spinal cord dorsal horn / hyperalgesia |
|---|
| Research Abstract |
Background : Since volatile anesthetics are capable of blocking sensory transmission, including pain sensation, at the level of the spinal dorsal horn(SDH), they could suppress incision-induced excitation during surgery and hence prevent or attenuate central sensitization of SDH neurons after surgery. In spite of this possibility, volatile anesthetics are generally considered to have little or no effects on central sensitization after surgery. The aim of this study was to determine whether halothane and isoflurane used during surgery can suppress or attenuate hyperexcitability of SDH neurons after an incision in the rat.
Methods : Activity of a single SDH wide-dynamic-range(WDR) neuron that had a receptive field(RF) on hairy skin of the hindquarter was isolated in decerebrate-spinal Sprague-Drawley rats, and neuronal activity(RF size and responses to non-noxious and noxious stimuli) was recorded. A l-cm-Long incision was made through the skin, fascia and muscle in the center of the RF u
… More
nder anesthesia with halothane(1.1% or 2.2%) and isoflurane(1.4% or 2.8%). Anesthesia was discontinued just after the incision had been made or was continued until 30min after the incision had been made, and activity of SDH neurons was measured for up to 2 hrs after the incision had been made. Data were compared with those obtained from control animals(control group) in which the incision was made without anesthesia.
Results : In the control group, the incision resulted in maximum excitation in the SDH neurons during surgery ; spontaneous activity significantly increased for up to 30min after the incision had been made(P<0.05) but did not significantly increase thereafter, returning to pre-incision levels. Halothane and isoflurane suppressed excitation of SDH neurons during the incision in a concentration-related manner. Administration of 2.2% halothane and 2.8% isoflurane during the incision and for up to 30min after the incision had been made abolished spontaneous activity of SDH neurons. for 30min after the incision had been made. The magnitude of the responses to the stimuli and expanded RF sizes were not significantly different in each anesthesia group compared to those in the control group. There were no significant relations between excitation during the incision and RF expansion after the incision or between the increase in spontaneous activity and RF expansion after the incision.
Conclusions : These results demonstrate that administration of halothane and isoflurane does not attenuate or prevent development of hyperexcitability of SDH neurons despite the fact that excitation of SDH neurons during the incision and spontaneous activity after the incision were greatly suppressed by administration of halothane and isoflurane, suggesting that central mechanisms are less involved in occurrence of incision-induced pain state than peripheral mechanisms. Less
|
Research Products
(13 results)
