A sinusoidal method for time-resolved quantification of dynamic brain extracellular space and diffusion tortuosity
作者单位：Multidisciplinary Research CenterShantou University
会议名称：《中国神经科学学会第四次会员代表大会暨第八届全国学术会议》
会议日期：2009年
学科分类：0710[理学-生物学] 07[理学] 071006[理学-神经生物学]
关 键 词：Extracellular Space Diffusion Ion-Selective Microelectrode Spreading Depression
摘 要：A sinusoidal iontophoresis method was proposed to determine the dynamic modulations of two important parameters for characterizing extracellular diffusion,the brain extracellular volume and diffusion tortuosity,during shortlived pathological events.This method improved the commonly used step-release protocol in better characterization of the time-resolved diffusion tortuosity by measuring the phase lags and sinusoidal amplitudes of the sampled tetramethyl ammonium(TMA) concentration waveform.To validate the sinusoidal method,we tested whether the dynamic diffusion properties in the brain extracellular space can be extracted reliably from the TMA sinusoidal waveform through computersimulated experiments.The TMA mass balance equation was first modified to accommodate temporal changes of the brain extracellular space,followed by solving the mass balance equation numerically to model the in vitro and in vivo experimental situations incorporating a sinusoidal TMA point source.Simulations showed that the sinusoidal method can accurately capture the dynamic behaviors of the simulated brain extracellular volume and tortuosity both in vitro and in vivo,as long as no abrupt changes of the two parameters were encountered.The sinusoidal method also proved to be more accurate in inferring the relative extracellular volume changes man the traditional method of monitoring the TMA background concentration in vitro,which produced significant TMA undershoot artifacts following pathological events.