Thurman R G, Lemasters J J
Department of Pharmacology, University of North Carolina, Chapel Hill 27514.
Drug Metab Rev. 1988;19(3-4):263-81. doi: 10.3109/03602538808994136.
New techniques employing microlight guides allow metabolic events to be studied noninvasively in tiny volumes of liver tissue located in defined regions within the liver lobule. These events include oxygen utilization, carbohydrate metabolism, ethanol oxidation, monooxygenation, glucaronidation, and sulfation. Two-fiber microlight guides are constructed from 80-microns optical fibers and are placed on periportal or pencentral regions of the liver lobule based on the pattern of liver pigmentation. Light of selected wavelengths is transmitted to the liver surface by one fiber, and the resultant fluorescence or reflectance is delivered to a photomultiplier by the second fiber. The experimental strategy is to monitor native fluors which are metabolically linked (e.g., NADH) or to infuse nonfluorescent substrates which are converted to fluorescent products by specific enzyme systems (e.g., 7-ethoxycoumarin for monooxygenation). Alternatively, disappearance of fluorescence can also be employed (e.g., 7-hydroxycoumarin for sulfation or glucuronidation). With these methods, rate-limiting steps in situ (e.g., substrate uptake, enzyme activity, cofactor supply) have been studied for several metabolic systems in periportal and pericentral regions of the liver lobule.
采用微光导的新技术能够对肝小叶特定区域内微小体积的肝组织进行无创代谢事件研究。这些事件包括氧利用、碳水化合物代谢、乙醇氧化、单加氧作用、葡萄糖醛酸化和硫酸化。双光纤微光导由80微米的光纤制成，根据肝脏色素沉着模式放置在肝小叶的门静脉周围或中央静脉周围区域。选定波长的光由一根光纤传输到肝脏表面，产生的荧光或反射光由第二根光纤传送到光电倍增管。实验策略是监测代谢相关的天然荧光物质（如NADH），或注入非荧光底物，这些底物可被特定酶系统转化为荧光产物（如用于单加氧作用的7-乙氧基香豆素）。另外，也可利用荧光消失的情况（如用于硫酸化或葡萄糖醛酸化的7-羟基香豆素）。通过这些方法，已对肝小叶门静脉周围和中央静脉周围区域的几种代谢系统原位的限速步骤（如底物摄取、酶活性、辅因子供应）进行了研究。
