Effects of propofol ,midazolam and thiopental on amino acid accumulation in ischemic areas in rats subjected to focal cerebral ischemia/reperfusion / 中华麻醉学杂志

ABSTRACT

Objective Increasing evidence shows that excitatory amino acids (EAAS) play an important role in the development of brain ischemia/reperfusion damage EAAS accumulation in ischemic tissues induces a sequence of biochemical reactions and eventually leads to cell death The aim of this study was to investigate the effects of propofol ,midazolam and thiopental on amino acid accumulation in ischemic areas in rats subjected to focal cerebral ischemia Methods Male SD rats weighing 240 260g were anesthetized with 10% chloral hydrate 350mg/kg and middle cerebral artery (MCA) occlusion was performed according to the method of Longa The animals were divided into 5 groups of 6 7animals each: group A (ischemia group) received 3 h MCA occlusion without reperfusion and medication; group B (ischemia/reperfusion group) received 3 h MCA occlusion followed by 3 h reperfusion without medication; group C,D and E received propofol or midazolam or thiopental 50mg/kg intrapentoneally after MCA occlusion but before reperfusion Commom carotid artery(CCA),external carotid artery (ECA) and internal carotid artery(ICA) were exposed through a longitudinal incision in the neck A 4 0 nylon thread with rounded tip was inserted into ICA through ECA and threaded cranially until slight resistance was felt The distance from the bifurcation of CCA to the tip of the nylon thread was about 22 cm In this way MCA was occluded After 3 h MCA occlusion the nylon thread was withdrawn to allow reperfusion After 3 h reperfusion the animals were sacrificed with lethal dose of chloral hydrate Brain was removed immediately Hemispheres of both sides were weighed separately and kept at -75℃ Concentrations of various amino acids (aspartate,glutamate,glycine,taurine and GABA) of each hemisphere were measured with high performance liquid chromatography Results Propofol and midazolam significantly reduced aspartate and glutamate accumulation in ischemic areas during reperfusion Propofol augmented but midazolam diminished GABA accumulation Thiopental had no significant effect Conclusions Propofol and midazolam may provide neuroprotection through acceleretion of excitatory amino acid elimination during reperfusion but thiopental does not