Irvine McQuairie 423 



Serum K is characteristically elevated in severe, inadequately controlled 

 diabetes mellitus. Rathery and Bertoliatti''^ found K values to average 35 per 

 cent above normal in seven cases of diabetes not on insulin therapy and 22 

 per cent above normal in seven insulin-treated cases. In a comprehensive study 

 of the serum electrolytes and acid-base equilibrium in four cases of severe 

 diabetes, Guest'^ found the Na and CI to be abnormally low and the K and 

 inorganic P to be gieatly elevated, when the patients were out of control. 7 o 

 him these changes appeared to be more closely related to prolonged duration 

 of the accompanying acidosis and to temporary impairment of renal function 

 than to the intensity of the acidosis, as indicated by the pH and the CO, con- 

 tent of the plasma. Insulin therapy caused a specific reversal of all of these 

 alterations, the serum K and inorganic P declining to subnormal levels. 



Comment 



It is evident, from the miscellaneous data presented here, that sodium and 

 potassium play important roles in carbohydrate metabolism. While there is 

 obviously a lack of complete agreement between the results of various workers 

 concerned with the problem of such interrelationships, differences in experi- 

 mental conditions apparently account for most of the discrepancies reported. 

 The mechanisms by which the Na and K ions influence carbohydrate economy 

 and those by which their exchanges in the body are in turn influenced by it 

 are not known. 



The roles of the two elements are obviously different and are in the main 

 antagonistic to each other. Potassium would appear to have the better claim 

 to an essential role in the intermediary metabolism. Its movements into and 

 out of the blood in company with glucose and inorganic PO^ or with lactic 

 acid under various conditions, have suggested that it may be organically bound 

 with some hexosephosphate compound or may be adsorbed to the surface of 

 the latter. The fact that the quantity of K involved in the deposition of glyco- 

 gen or released with its breakdown is far less than the glycogen (measured 

 in equivalents), argues against the assumption that it enters into direct chem- 

 ical combination with the carbohydrate as PO^ does in the process of phos- 

 phorylation. At present it would appear more likely that K plays the role 

 of accelerating certain enzymatic reactions involved in carbohydrate metabo- 

 lism, just as magnesium, manganese and cobalt have been sho^vn by Cori'^ to 

 do in the case of the enzyme, phosphoglucomutase. It has already been shown 

 to accelerate the fermentative and oxidative breakdown of glucose in yeast 

 cultures and in fresh tissue slices. The suggestion that its physical relationship 

 to the complex carbohydrate molecule is one of adsorption becomes more 

 likely in the light of this latter role. 



Sodium does not move into or out of the blood or other media with glucose 

 and inorganic PO^ (Ziegler™). Nor is it known to activate enzymatic reactions 

 under simple experimental conditions similar to those in which the accelerat- 

 ing effect of K has been demonstrated. Its influence on carbohydrate metabo- 



