CORRELATION OF DIFFUSION, BLOOD VOLUME & DC POTENTIAL CHANGES IN BRAIN: ISCHEMIA

简介：MRI检测明显快速下降 脑缺血时脑组织的弥散系数（ADC）被认为 由于能量衰竭后的细胞毒性水肿， 血流的停止。 这项研究旨在快速关联 采集的ADC测量值与直流电位（作为 细胞膜极化的指示物）， 心脏骤停 方法：雄性SD大鼠麻醉后， 用氟烷。 将氯化银电极置于皮质上 通过钻孔测量大脑直流电位 DC和MABP是 连续记录。 在2.0T GE Omega系统上进行MRI 使用回波平面成像。 扩散和非扩散加权 每6秒交替图像以测量大脑上的ADC。 定义了三组动物：正常、高血糖和 低血糖 在15分钟之前和15分钟内连续采集图像 心脏停搏后10分钟静脉注射KCl。 结果：MABP KCl注入后5秒内降至零。 ADC立即开始 缓慢下降，然后突然大幅下降， 保持恒定或再次缓慢下降，直到扫描结束。 各组MABP下降与ADC值快速下降之间的延迟 为（平均值1 s. d.）分钟）：正常1.4210.17（n=7），高血糖 2.85 ± 10.83（n=5），低血糖0.94 ± 10.39（n=5）。 对应值 正常组1.42 ± 10.8（n=5），高血糖组3.50 ± 10.76（n = 5 （n=3），低血糖0.62 ± 0.17（n=2）。 结论：渐进ADC MABP下降后立即开始下降，这可能是由于 瞬时跨膜水转移。 随后， ADC与缺氧细胞膜去极化同时发生;两者 这些变化被超或 低血糖

Introduction: The rapid decline in MRI detected apparent diffusion coefficient (ADC) of brain tissue during ischemia is thought to be due to cytotoxic edema following energy failure resulting from the cessation of blood flow. This study aims to correlate rapidly acquired ADC measurements with DC electrical potential (as an indicator of cell membrane polarization) during global ischemia by cardiac arrest. Methods: Male Sprague-Dawley rats were anesthetized with halothane. A chlorided silver electrode was placed on the cortex through a burr hole, to measure brain DC potentials. DC and MABP were recorded continuously. MRI was performed on a 2.0T GE Omega system using echo planar imaging. Diffusion and non-diffusion weighted images were alternated to measure ADC over the brain every 6 seconds. Three groups of animals were defined: normal, hyperglycemic and hypoglycemic. Images were acquired continuously before and up to 15 minutes after cardiac arrest by i.v. KCl injection. Results: MABP fell to zero within 5 seconds of KCl injection. ADC immediately began to decline slowly, followed by a sudden and large decline and then remained constant or declined slowly again until the end of the scan. The delay between MABP drop and the rapid ADC decline in each group was (mean1s.d. minutes): normal 1.4210.17 (n=7), hyperglycemic 2.8510.83 (n=5), hypoglycemic 0.9410.39 (n=5). Corresponding values for the DC drop were: normal 1.4210.8 (n=5), hyperglycemic 3.5010.76 (n=3), hypoglycemic 0.6210.17 (n=2). Conclusion: A gradual ADC decline begins immediately upon MABP decrease, which may be due to an instantaneous transmembrane water shift. A subsequent rapid drop in ADC occurs coincident with anoxic cell membrane depolarization; both changes were delayed or accelerated together by hyper- or hypoglycemia.