The Respiratory Quotient in Diabetes. 



125 



75 (1007) 



The respiratory quotient in diabetes. 



By Graham Lusk. 



[From the Physiological Laboratory of the Cornell University Medical 

 College, New York City.} 



Oxidation of protein in the body really consists in the destruc- 

 tion of a great variety of amino-acids. When glucose arises from 

 protein in diabetes the oxidation is different from the normal. 

 When the D : N ratio is 3.65 the respiratory quotient for protein 

 falls from 0.801 to 0.634. From Osborne's analyses of meat 

 protein, recalculated on the basis of Osborne's own determination 

 of the deficiency of the analytical methods employed, it may be 

 calculated that the six sugar-forming amino-acids, glycocoll, 

 alanine, aspartic acid, glutamic acid, proline and arginine, are 

 present to the amount of 64.5 grams in 100 grams of meat protein. 

 From the work of Ringer and Lusk and of Dakin and Dudley, it 

 may be estimated that 44.4 grams of glucose arise from the several 

 quantities of these amino-acids contained in 100 grams of meat. 

 This would indicate a D : N of 2.75 and would explain the origin 

 of 76 per cent, of the maximal sugar production from protein. 



The estimated quantity of 64.5 grams of sugar-forming amino- 

 acids would yield a respiratory quotient of 0.915 when oxidized 

 normally, but if 44.4 grams of glucose be produced from them the 

 respiratory quotient sinks to 0.675. 



If one subtracts the influence of these sugar-forming amino- 

 acids and the influence of the 1.07 grams of protein ammonia from 

 the normal respiratory exchange, one may calculate that the 

 respiratory quotient which represents the oxidation of the non- 

 sugar-forming amino-acids is 0.716. 



If one turns to Osborne's analyses it is found that the non- 

 sugar-forming amino-acids consist in larger part (20 grams) of 

 leucine, lysine and valine with respiratory quotients of 0.73, 

 0.71, 0.75 and in lesser quantity (7 grams) of histidine, phenyl- 

 alanine and tyrosine with quotients of 0.90, 0.87, 0.89. Using 

 Osborne's uncorrected figures (for corrections for lysine are not 



