108 LIFE: ITS NATURE AND ORIGIN 



summarized the work of A. V. Hill, W. Hartree, O. Meyerhof 

 and others as follows: 21 "When the muscle tissue contracts and 

 does work it derives the necessary free energy, not from oxidation, 

 which is not quick enough, but from the rapid exothermic con- 

 version of the carbohydrate glycogen into lactic acid. When the 

 fatigued muscle recovers, it recharges its store of free energy; that 

 is to say, by oxidizing or burning some of the carbohydrate, it 

 reconverts the lactic acid into glycogen. Thus in the recovery 

 stage we have the coupled reactions of exothermic oxidation and 

 the endothermic conversion of lactic acid into glycogen." 



In a fuller discussion, including more recent work, Professor Otto 

 Meyerhof 22 observes: "Three different anaerobic reactions were found 

 to be related to activity and also to be linked to one another: (1) 

 splitting of carbohydrate, preformed in the muscle as glycogen and 

 hexose-6-monophosphate, into lactic acid via phosphorylated inter- 

 mediaries and pyruvic acid; (2) splitting of phosphocreatine into 

 creatine and phosphate; (3) splitting of adenosine triphosphate to 

 adenylic acid plus 2-phosphate via adenosine-diphosphate plus 1- 

 phosphate." The lactic acid formation restores the phosphocreatine, 

 broken down in the earlier stages of activity, while the breakdown of 

 phosphocreatine is able to restore the adenosine triphosphate, and 

 the oxidation of carbohydrate can reverse every cleavage reaction of 

 (1), (2), and (3), whose respective energy stores are given as 1.2 Cals, 

 0.23 Cal, and 0.09 Cal respectively, whereas carbohydrate oxidation 

 into COo + H 2 is listed as 30 — 60 Cals, and is, therefore, the main 

 energy source. For many other important details and references, 

 Meyerhof's paper must be consulted. 



Summing up current views, Brody 23 points out that phosphate 

 occupies a key position in biological oxidation. Pasteur observed 

 its importance in 1860, Young and Harden confirmed it in 1905, 

 and it is at present being extensively investigated by the Cori, 

 Lipmann, and Meyerhof schools, among others. 24 Brody states: 

 "... some phosphate esters serve as temporary biologic energy 

 reservoirs, analogous to charged batteries. Thus, according to 

 Cori, the synthesis of 6 molecules of glucose phosphate is coupled, 

 or associated, with the oxidation of one molecule of glucose. A 

 mol of glucose phosphate, therefore, has a labile energy increment 

 which, depending on the energetic efficiency of the process, may 

 be as high as 115 Cal ($ of about 700 Cal, the free energy of glu- 

 cose). This is, presumably, what Lipmann refers to as phosphate- 



