Alexander G M, Grothusen J R, Schwartzman R J
Department of Neurology, Jefferson Medical College, Philadelphia, PA 19107.
Life Sci. 1988;43(7):595-601. doi: 10.1016/0024-3205(88)90063-x.
The relative efficiencies of microdialysis probes were determined both in vitro and in vivo using tritiated water. Tritiated water (THO) freely distributes throughout the fluid spaces of an experimental animal and, at equilibrium, the brain extracellular concentration of THO is the same as the plasma concentration. Microdialysis probes were inserted into the right caudoputamen of anesthetized rats. The rats were injected with THO and after one hour microdialysis samples were collected at flow rates between 0.2 and 10.0 ul/min. The in vitro relative efficiency for THO was computed as the ratio of the THO concentration in the dialysate to that of the solution the probe was immersed in. The in vivo relative efficiency was computed as the ratio of the concentration of THO in the brain dialysate to that measured in the plasma of the rat. Both the in vitro and in vivo relative efficiencies for THO decrease with increasing flow rates, but they differ from each other except at very low flow rates (less than 0.25 ul/min). The in vitro relative efficiency at a given probe flow is the maximum efficiency that can be attained in vivo at that flow. The surface of effective exchange (Se) is the fraction of that maximum which is attained in vivo. This study also demonstrates how the effective surface area can be computed at any probe flow rate and how it can be used as a correction factor.
使用氚标记水在体外和体内测定了微透析探针的相对效率。氚标记水（THO）可在实验动物的整个体液空间中自由分布，并且在平衡时，THO的脑细胞外浓度与血浆浓度相同。将微透析探针插入麻醉大鼠的右侧尾壳核。给大鼠注射THO，1小时后以0.2至10.0微升/分钟的流速收集微透析样品。THO的体外相对效率计算为透析液中THO浓度与探针浸入溶液中THO浓度的比值。体内相对效率计算为脑透析液中THO浓度与大鼠血浆中测量浓度的比值。THO的体外和体内相对效率均随流速增加而降低，但除了在非常低的流速（小于0.25微升/分钟）下，它们彼此不同。给定探针流速下的体外相对效率是该流速下体内可达到的最大效率。有效交换表面（Se）是体内达到的最大效率的一部分。这项研究还展示了如何在任何探针流速下计算有效表面积以及如何将其用作校正因子。
