Effect of coal dusts containing heavy metals on structure, cellular enzymatic markers, and cytochrome P-450-dependent monooxygenase system in rat kidney

We evaluated morphological changes, the activities of succinate dehydrogenase, lactate dehydrogenase, glucose-6-phosphatase, Mg2+ -dependent adenosine triphosphatase, and acid phosphatase, and the activity of the cytochrome P-450-dependent monooxygenase system in the kidneys of rats exposed to coal dusts containing either very low or high amounts of heavy metals. We showed that the coal dust with a very low content of heavy metals (VLCHM) did not produce any structural lesions, but increased significantly the activities of the enzymes. These changes probably reflected kidney adaptation to the unfavorable conditions caused by the metals. The interactions among them reduced the eventual nephrotoxic effect of their action. The coal dust with a high content of heavy metals (HCHM) damaged proximal convoluted tubules, straight tubules, and, to a lesser degree, distal convoluted tubules, especially those of long-looped nephrones. The levels and the activities of the assayed cytochromes decreased significantly in the kidneys of rats exposed to HCHM coal dust.