PHOSPHATES AND THERAPEUTIC AGENTS 



149 



phosphates in shces incubated without phenobarbitone. Since 

 measurements of radioactivity were made at a time when the 

 general movement of radioactivity was out of rather than into these 

 phosphates (see Fig. 13) the resuhs were considered to mean that 

 the point of the action of phenobarbitone hes in blocking some 



10 30 60 90 



Period of stimulation (sec) 



120 

 



Period of resynthesis 



10 



20 



(sec) 



Fig. 17. The breakdown and resynthesis of phosphocreatine in 

 cerebral slices in the presence and absence of phenobarbitone, 

 1-7 X 10"^ M. Slices were stimulated with electrical condenser 

 impulses. • = with phenobarbitone; O = without pheno- 

 barbitone. Data from Cohen and Heald (1960). 



processes involved in the utilization of energy-rich phosphates 

 beyond the point of phosphoprotein. 



Other agents active upon stimulated respiration have so far been 

 studied only in relation to their effects upon phosphocreatine 

 metabolism. Thus with guinea pig cerebral slices cocaine at 

 2 X 10'^ M reduced the breakdown of phosphocreatine in response 

 to electrical pulses the rate being some 30 ^itmoles/g hr-^ or 3% of 

 the normal rate. At this concentration little effect was noted upon 

 the resting oxygen uptake and the normal levels of phosphocrea- 

 tine were not altered (Bollard and Mcllwain, 1959). On the other 



