Chapter 6 



CELL DAMAGE PRODUCED BY 

 TOXIC AGENTS 



A. 



.s described in the chapter devoted to enzymes, modern work 

 suggests that many poisons produce their harmful effects by dis- 

 turbing the respiratory mechanism of cells. In this section, which 

 is devoted to a more detailed consideration of the subject, we shall 

 therefore first of all recapitulate the main stages in cellular respira- 

 tion, attempt to localise them within the cell and then see how 

 poisons destroy cells by interrupting this aspect of metabolism. 



CELL RESPIRATION 

 (SEE ALSO CHAPTER 5) 



Cell respiration makes use of the following devices: 



1. The glycolytic system. 



2. The hexose monophosphate shunt. 



3. Enzymes of the Krebs cycle and of related aerobic metabol- 

 ism. 



4. The electron transport system. 



5. The accompanying system for oxidative phosphorylation. 

 Many of these enzyme systems are concentrated in the mitochondria 

 but other cellular components are certainly involved in some, if 

 not all of these processes. 



Glycolytic activity is a function of all mitochondria (de Buy 

 and Hesselbach, 1956) but its exact localisation in the cell is still 

 in doubt. Technical difficulties concerned in establishing this as- 

 sociation are still considerable and it is uncertain whether the 

 enzymes of glycolysis leak out from mitochondria during the mani- 

 pulations used in the isolation of cellular components for such 

 studies. During glycolysis glucose is broken down step-wise, by 

 enzymic action and interactions with ATP, to pyruvate (See Fig. 

 4) . Eventually the latter is transformed through aerobic metabol- 

 ism to C0 2 and water with liberation of some of its latent energy 

 for use by the cell. 



71 



