| Abstract: | Kinetics of the content of nonheme iron-sulphur-containing (iron-sulphur) proteins, free radicals of electron-transport mitochondrial system, as well as of microsome terminal oxidase cytochrome P-450 is studied in the liver of rats at early stages of carcinogenesis and in the process of tumour growth induced by intratracheal administration of various benz(a)pyrene doses. It is found that the content of iron-sulphur proteins increases after the first administration, then it falls against a background of higher concentration of free radicals. A degree of pronounced changes in the content of the studied iron-sulphur proteins correlates with carcinogen dose. The cytochrome P-450 content is lowered for almost the whole period of carcinogen administration. In later periods animals with morphologically determinable pretumour changes exhibit a much higher content of iron-sulphur proteins, somewhat increased concentration of free radicals and a tendency to an increased level of cytochrome P-450. The appearance and growth of malignant tumours is followed by a considerable decrease in the content of iron-sulphur proteins and cytochrome P-450. On the basis of the results obtained it is supposed that the changes in the content of iron-sulphur proteins in the rat liver is the earliest and most pronounced reaction which depends on the benz(a)pyrene dose and may be of prognostic significance. |
