猫急性脑血管痉挛早期脑血流和脑组织谷氨酸的变化

目的观察猫大脑中动脉(MCA)受机械性刺激痉挛后早期(2h内)的血管直径、脑血流量和谷氨酸变化。方法6只猫开颅暴露右侧MCA,机械刺激MCA30min,测量刺激前后MCA直径的变化,监测皮层脑组织灌流指数,测定脑皮层细胞间隙中谷氨酸浓度的变化。结果机械性刺激MCA后,MCA直径缩小,为刺激前的68·2%。脑组织灌流指数下降到刺激前的48·7%。刺激结束后2h,MCA直径恢复正常。脑组织灌流指数恢复到刺激前的63·8%。机械刺激期间谷氨酸浓度迅速增加,可达到正常值的40倍,在撤除刺激后,谷氨酸浓度没有明显减少。结论机械性刺激可致脑血管痉挛,脑血流量降低,兴奋性氨基酸升高。

Changes of Cerebral Blood Flow and Glutamate Level in the Early Stage of Acute Mechanical Cerebral Vasospasm in Cat

ObjectiveTo observe the changes of artery diameters, cerebral blood flow and glutamate level in the early stage (2 h after the stimulus finished) of acute mechanical middle cerebral artery (MCA) vasospasm in cats. MethodsThe right MCA was persistently mechanically stimulated using a small smooth stainless steel nail in the field across the olfactory tract for 30 min. The diameter of MCA was recorded with metrical ocular of microscope. The changes of the perfusion index of brain tissue were observed through the Laser Doppler flowmetry monitor fixed on the skull. The level of glutamate were investigated through high performance liquid chromatography. ResultsThe diameter of MCA decreased to 68.8% of normal. 2 h later, the diameter of MCA recovered. The perfusion index of the cortex surface decreased to 42.6% of normal and up to 63.8% 2 h later. The level of glutamate raised about 40 times of normal and maintained a high level 2 h after the mechanical stimulus. ConclusionThe persistent mechanical stimulus can cause acute cerebral vasospasm. Reduce of cerebral blood flow and raise of excitatory amino acids were observed in the early stage of acute mechanical vasospasm.