CONTROL OF RATE OF INTRACELLULAR 

 RESPIRATION 



E. C. Slater and W. C. Hulsmann 

 Laboratory of Physiological Chemistry ^ University of Amsterdam 



Aerobic cells are able to bring about the complete oxidation 

 of glucose, according to reaction (i) 



CeHiaOe + 6 O^ -> 6 COg + 6 HgO (i) 



which is catalysed by a complex system of enzymes within the 

 cell. If glucose and oxygen are introduced into the cells con- 

 taining these enzymes, reaction (i) predicts that glucose will 

 be oxidized at a rate governed by the concentration of the 

 enzymes. However, it is well known that animals can vary 

 the rate of their metabolism, and their oxygen consumption, 

 according to their needs. For instance, the oxygen consump- 

 tion of the working leg muscle of a man can be increased about 

 sixty-five times during the performance of work (Asmussen, 

 Christensen and Nielsen, 1939). The heart muscle, also, 

 although normally it works at fairly constant activity can 

 increase its oxygen consumption appreciably and, more 

 interestingly, it is possible to stop the oxygen consumption 

 of the heart by bringing about cardiac arrest by injection of 

 potassium citrate into the coronary circulation (Melrose et al., 

 1955). 



There must, therefore, be mechanisms controlling the rate 

 of reaction (i). One mechanism, which is under hormonal 

 control, concerns the rate at which glucose can enter the cell. 

 Our present discussion will not, however, deal with this 

 question, but will be concerned with possible mechanisms 

 which control the rate of oxidation of the intracellular 

 glucose and other products of the digestion of foodstuffs. 



A mechanism of control of the respiratory rate which is 



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