PHOSPHATES AND THERAPEUTIC AGENTS 



139 



are likely also to combine with others not normally affected. The 

 metabolic changes then measured could be of a non-specific type. 

 Concentrations of some of the agents most studied, which have 

 been found in the brain in vivo following a therapeutic dose are of 

 the order of 1-5 X 10" ^ M for the barbiturates and 10" "^ M for a 

 tranquillizing agent such as chlorpromazine (Table 21). Concen- 

 trations much in excess of these alter the phosphate metabolism of 

 cerebral slices and homogenates but do so largely as a result 

 of their first depressing the oxygen uptake. Thus, chloral at 



Table 21. — Concentrations of Various Agents in Animal Brain 

 Following the Administration of a Therapeutic Dose 



Depressants were assayed following an anaesthetic dose in dogs and 

 rabbits. Chlorpromazine following 100 mg/kg given to mice. Data from 

 Mark et al. (1958); McClennan and Elliot (1951); Butler (1950); Berti 

 and Cima (1954); Buchel and Mcllwain (1950); Truitt et al (1956); and 

 Goldbaum (1948). 



