흰쥐에 초산납 투여가 신장조직중 Free Radical 대사효소 활성과 초미형태학적 변화에 미치는 영향

Abstract

To investigate the ultrastructural changes of kidney and clarify to a cause of its changes in lead intoxicated rats, the 0.5% lead acetate administed orally to the rats and those were sacrifled at 2 day, 1, 2, 4, 6 and 8 week after the treatment of lead acetate. Each extirpated kidney was histopathologically examined under the electron microscopy and histochemical examination was also carried out. Concomitantly, the activity of free radical metabolizing enzyme was determined. The blood levels of lead concentration showed a gradual increase from the first group reaching the plateau at the one or two week group with the slightly decreasing value throughout the whole course of the experiment. And the urinary ALA concentration showed a gradual increase from the first group to the 8 week group. In the kidney tissue of rat sacrified at 6 week, the proximal tubular cells showed dilatation of endoplasmic reticulum, mitochondrial swelling, increased numbers of secondary lysosomes and myelin figure-like residual bodies on electron microscope and oxygen free radicals are identified by histochemistry on light microscope whereas there were no differences in the activity of catalase and glutathione peroxidase between the lead acetate treated group and control group. But the activity of xanthine oxidase was more increased in lead acetate treated rats than control group. Furthermore, the superoxide dismutase activity was significantly increased in the experimental group than the control group. In conclusion, it is assumed the kidney damage in lead intoxicated rat may be induced by free radicals.

납에 의한 신장손상의 기전을 규명하는 일환으로 흰쥐에 초산납(0.5%)을 8주까지 음용시킨 다음 경시별로 처치한 후 요중 ALA 농도와 혈중 납 농도를 측정함과 동시에 신세포의 초미형태학적으로 관찰하여 신세포의 손상을 관찰하였다. 또한 신세포의 oxygen free radical을 조직화학적으로 확인한 후 oxygen free radical의 대사에 관련된 효소 활성을 측정하여 다음과 같은 결과를 얻었다. 초산납 투여후 2일째부터 혈중 납농도가 유의하게 증가되었으나 이때 요중 δ-ALA 농도 역시 전 실험기간 동안 점진적인 증가를 보였으며 6주째 부터 현저한 증가를 보였다. 또한 초산납 투여 6주째 전자현미경상에는 mitochondria와 ER의 종창 등이 보였고 산소유리기의 염색에서는 양성 반응을 나타내었으며 이때 신조직중 xanthine oxidase 활성이 대조군에 비하여 증가되었으며 superoxide dismutase 활성은 대조군 보다 현저히 증가되었다. Catalase 및 glutathione peroxidase 활성은 초산납 투여군과 대조군간에는 별다른 차이를 볼 수 없었다. 이상 실험겨로가를 종합해 볼 때 납에 의한 신장손상은 oxygen free radical에 기인된 결과로 생각된다.