Endou H
J Toxicol Sci. 1983 Aug;8(3):165-76. doi: 10.2131/jts.8.165.
Intrarenal distribution of cytochrome P-450 (P-450) was investigated with different segments of isolated single nephrons from rabbits and rats by using a new ultra-micro method of P-450 determination. In both animals, P-450 was localized only in the proximal tubule. Other segments such as the glomerulus, the loop of Henle, the distal tubule, and the collecting tubule possessed no P-450 at all. Within the proximal tubule, the straight portion (S2 and/or S3 segments) revealed a higher specific content of P-450 than the convoluted one. An inducer of P-450, 3, 4-benzo(a)pyrene increased the P-450 of a definite portion (second 3 mm from the glomerulus) almost doubly in rabbits. In rats, both 3-methylcholanthrene (3MC) and 48 hr starvation (Fast) induced P-450, but only the later increased laurate-omega-hydroxylation. P-450 in the proximal convoluted and straight tubules was induced separately by Fast and 3MC, respectively. These results indicate that renal mixed function oxidase should be confined to the proximal tubule and that, like the liver, multiple forms of renal P-450 should exist in the different proximal segments.
采用一种新的细胞色素P - 450（P - 450）超微测定方法，对兔和大鼠分离的单个肾单位的不同节段进行了肾内P - 450分布的研究。在这两种动物中，P - 450仅定位于近端小管。其他节段，如肾小球、髓袢、远端小管和集合小管均未检测到P - 450。在近端小管内，直部（S2和/或S3段）的P - 450比曲部具有更高的比含量。P - 450诱导剂3,4 - 苯并(a)芘使兔特定节段（距肾小球3mm处）的P - 450含量几乎增加了一倍。在大鼠中，3 - 甲基胆蒽（3MC）和48小时饥饿（禁食）均能诱导P - 450，但只有禁食能增加月桂酸ω - 羟化作用。近端曲管和直小管中的P - 450分别由禁食和3MC单独诱导。这些结果表明，肾混合功能氧化酶应局限于近端小管，并且与肝脏一样，肾内不同近端节段应存在多种形式的P - 450。
