CHAPTER I 



METABOLISM IN THE NORMAL 

 FUNCTIONAL STATE 



The brain in vivo derives its supply of energy by the oxidation of 

 glucose, consuming in the process one-fifth of the total bodily 

 consumption of oxygen. In common with other organs of the 

 body such energy is stored and transmitted by phosphates of 

 which adenosine triphosphate and phosphocreatine are prominent. 

 In the brain, many other phosphorylated compounds exist, the 

 functions of many of which are either partly or entirely unknown. 

 A method of attempting to understand the role such phosphates 

 play in cerebral metabolism is the examination of their behaviour 

 under a variety of different conditions. In this Section the meta- 

 bolism of the phosphorus compounds of brain in vivo is considered, 

 first, as it occurs in animals under normal unstressed conditions, 

 and second, as it is affected by a number of changed circumstances. 

 The subject matter of Chapter 1 is, therefore, a description of the 

 normal metabolic state of the brain as it relates to phosphorus 

 metabolism. 



Quantities of Phosphorus Compounds in the Brain 



Acid- soluble Phosphates 



Amongst the phosphates of brain those extracted by acid 

 denaturants such as trichloracetic acid have received considerable 

 attention over the past fifteen years. The major ones are the 

 adenosine polyphosphates, phosphocreatine and inorganic phos- 

 phate. The quantities of these phosphates found in brain of 

 different species are given in Table 1 . To obtain reliable estimates 

 of the quantities such as these the brain must be frozen in situ with 

 liquid oxygen or nitrogen and removed, while still frozen, to the 

 acid denaturant with which it is then rapidly ground. Small 

 animals such as the mouse, rat, or guinea pig, are frozen whole by 

 dropping into a flask of liquid nitrogen. With larger animals such 



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