氯胺酮对外周神经传导的影响

１２只戊巴比妥钠麻醉的猫，观察了神经干局部和静脉使用氯胺酮（ｋｅｔａｍｉｎｅ，ＫＥＴ）对神经干复合动作电位的影响。结果显示：（１）局部施加较高浓度的ＫＥＴ（３．６、７．２、３６、７２和１８０ｍｍｏｌ）对Ａβ，Ａ和Ｃ波具非选择性可逆性抑制作用，且与剂量呈正相关。而较低浓度的ＫＥＴ（０．９和１．８ｍｍｏｌ）对动作电位不仅不抑制，反而有兴奋效应；（２）静脉注射 ＫＥＴＳ和 １０ｍｇ／ｋｇ对约半数的 Ａβ，Ａ和 Ｃ波有兴奋作用，而无抑制效应。上述结果表明，ＫＥＴ可以通过非突触作用直接影响外周神经冲动的传导，而较高浓度和较低浓度的ＫＥＴ则可通过不同的机制分别对神经冲动的传导产生抑制和兴奋作用。

Effects of ketamine on the conduction of peripheral nerve.

The effects of ketamine on the conduction of peripheral nerve were investigated in 12 adult cats. After foe anesthesia was induced by intraperitoneal injection of sodium pentobarbital,the cats underwent the transverse amputation of spinal cord between the first and second lumbar vertebra. The electrical stimulation was applied to the fibular nerve (FN),the site of which was distal to that of measuring the compound action potentials (CAP). Before and after ketamine was topically administrated to the part of FN between the sites of stimulation and recording at different concentrations,the amplitudes,latencies and durations of and C waves of CAP were recorded respectively. The results showed that the amplitudes were markedly reduced,and the latencies and durations were dramatically prolonged respectively by topical administrations of ketamine at higher concentrations of 3. 6, 7. 2, 36, 72 and 180mmol (P<0. 01 ),with the parallel relationship between the degrees of variation and levels of concentration. In contrast,the amplitudes were increased by ketamine administrated topically at lower concentrations of 0. 9 and 1. 8mmol and intravenously at doses of 5 and 10 mg. kg-1 individually (P<0. 05 ). Following the withdrawal of topical ketamine,CAP returned to normal status It is suggested that ketamine has direct reversible non sisynaptic actions on the conductian of peripheral nerve,and the nature of the actions,either inhibition or excitation,appears to be a strong link with the dosage.