86 



ELECTROLYTES IN BIOLOGICAL SYSTEMS 



concentration will return the rate to the maximal value (fig. 12). Thus H+ 

 inhibits fermentation and K+ counteracts its action. Apparently the relation- 

 ship between K+ and H+ in this case is competitive. The inhibition by a given 



Table 7. Effects of various ions on fermentation of glucose in presence and absence 



OF potassium 



Control 



Li 



Na 



K 



Rb 



Cs 



NH4 



Mg 



Ca 



Individual Ions, 

 CO: in jil/mg hr. 



24. I 



27.2 



28.2 



44.0 



33-8 



26.5 



26.5 



28.6 



30.0 



pH 2.7; ion concentration, 0.02 m/1. 



All values are averages of 2 experiments. 



50 



40 



30 



20 



10 



U8 



I 



-2 

 4. 



- 2 



»- 



u 



3 



O 



Fig. 12. The effect of the po- 

 tassium concentration on the rate 

 of fermentation at different pH 

 values. 



concentration of H+ can be completely reversed by the addition of 10 times the 

 concentration of K+. 



The dramatic effects of K+ are observed only when glucose, or other sugars, 

 serve as substrates. There is only a small effect of these ions on the respiration of 

 substrates such as alcohol or endogenous stores. Furthermore, the stimulating 

 action of K+ is most prominent during fermentation of sugars, rather than 



