Increasing isoflurane from 0.9 to 1.1 minimum alveolar concentration minimally affects dorsal horn cell responses to noxious stimulation
Increasing isoflurane from 0.9 to 1.1 minimum alveolar concentration minimally affects dorsal horn cell responses to noxious stimulation
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DOI：
10.1097/00000542-199901000-00027
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发表时间：
1999-01-01
期刊：
影响因子：
8.8
通讯作者：
Carstens, E
中科院分区：
文献类型：
--
作者：
Antognini, JF;Carstens, E
背景：脊髓似乎是异氟醚抑制对有害刺激反应的运动的部位。为了确定其抑制作用的位置，作者确定了异氟醚对背角神经元对潮末浓度下的超最大值有害刺激的反应的影响，这些刺激刚好允许和刚好阻止运动。方法：用异氟醚麻醉大鼠（n = 14），腰椎椎板切除术后，采用超最大值机械刺激测定每只大鼠的最小肺泡浓度（MAC）。在这些大鼠中，在腰椎脊髓放置细胞外微电极后，在每只大鼠的MAC（比MAC高0.1%和低0.1%）周围的异氟醚浓度下，测定背角神经元对超极大刺激的反应。然后重新测定异氟醚的MAC。结果：0.9 MAC时背角神经元反应为1757 +/- 892脉冲/min， 1.1 MAC时为1508 +/- 988脉冲/min，下降14% （P < 0.05）。细胞对异氟烷的反应各不相同，在异氟烷浓度较高时，部分细胞的反应增强，测定背角神经元反应前异氟烷的MAC值为1.38 +/- 0.2%，测定背角神经元反应后MAC值为1.34 +/- 0.2%。结论：异氟醚在达到MAC浓度时，对背角细胞对有害机械刺激的反应具有可变且最小的抑制作用。这些数据表明，异氟醚抑制有害刺激引起的运动的主要作用可能主要发生在背角以外的部位。
Background: The spinal cord appears to be the site at which isoflurane suppresses movement that occurs in response to a noxious stimulus. In an attempt to localize its site of suppressant action, the authors determined the effect of isoflurane on dorsal horn neuronal responses to supramaximal noxious stimulation at end-tidal concentrations that just permitted and just prevented movement.Methods: Rats (n = 14) were anesthetized with isoflurane, and after lumbar laminectomy, the minimum alveolar concentration (MAC) for each rat was determined using a supramaximal mechanical stimulus. In these same rats, after extracellular microelectrode placement in the lumbar spinal cord, dorsal horn neuronal responses to the supramaximal stimulus were determined at the concentrations of isoflurane that bracketed each rat's MAC (0.1% higher and lower than MAC). The MAC of isoflurane was then re-determined.Results: Dorsal horn neuronal response was 1,757 +/- 892 impulses/min at 0.9 MAC and 1,508 +/- 988 impulses/min at 1.1 MAC, a 14% decrease (P < 0.05). Cell responses varied, with some cells increasing their response at the higher concentration of isoflurane, The MAC of isoflurane was 1.38 +/- 0.2% before and 1.34 +/- 0.2% after determination of dorsal horn neuronal responses.Conclusions: Isoflurane, at concentrations that bracket MAC, has a variable and minimal depressant effect on dorsal horn cell responses to noxious mechanical stimulation. These data suggest that the major action of isoflurane to suppress movement evoked by a noxious stimulus might occur primarily at a site other than the dorsal horn.