Effect of noxious stimulation factor on γ-aminobutyric acid distribution in dog spinal cord during propofol anesthesia / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of the noxious stimulation factor on γ-aminobutyric acid (GABA) distribution in dog spinal cord during propofol anesthesia.Methods Sixteen healthy mongrel dogs of both sexes,aged 12-18 months,weighing 10-12 kg,were randomly divided into 2 groups (n =8 each)noxious stimulation group (S group) and control group (C group).Anesthesia was induced with propofol 7 mg/kg.The animals were mechanically ventilated after tracheal intubation.Right femoral artery was cannulated for mean arterial pressure (MAP) and pulse rate monitoring.Anesthesia was maintained with propofol infusion at a constant rate of 70 mg· kg-1 · h-1.5 ％ formalin 300 μl was subcutaneously injected into the central region of tails in group S,while the equal volume of normal saline was injected instead of formalin in group C.MAP and pulse rate were recorded before injection of formalin or normal saline (T1) and after injection of formalin or normal saline (T2).The dogs were scarified by decapitation at 50 min of continuous propofol infusion and cervical 2-3 segments of the spinal cord were removed for determination of GABA level in different regions of the spinal cord (frontal horn,posterior horn,intermediate zone,frontal funiculus,posterior funiculus and lateral funiculus) by HPLC.Results MAP and pulse rate were significantly higher at T2 than at T1 in S group (P ＜ 0.05).There were no significant differences in GABA level among the different regions of the spinal cord in C group (P ＞ 0.05).Compared with C group,GABA level in the frontal horn and posterior horn was significantly increased (P ＜ 0.05),and no significant change was found in the other regions of the spinal cord in S group (P ＞ 0.05).Conclusion The noxious stimulation factor can induce an increase in GABA level in the frontal horn and posterior horn of dog spinal cord during propofol anesthesia.