144 



ELECTROLYTES IN BIOLOGICAL SYSTEMS 



stant of the process is greater in O2 than in No . However, the assumption that 

 the K outflux is entirely by diffusion, which is somewhat dubious even for the 

 duck cell in O2 , completely breaks down for the duck cell incubated in N2 . 

 Thus, D'k calculated from the concentration curve is essentially zero, much 

 smaller than the value .067 calculated from the flux ratio analysis. 



Relation of K Transport to Metabolism, a) Effect of gas composition. As 

 noted above, incubation of duck red cells in N2 rather than O2 converts me- 

 tabolism from respiration to glycolysis and accelerates the inward transport 

 of K by chemical reaction. When [K],n is 5 mn/l., the steady state K flux in 

 duck cells incubated at 37°C is 20 mM/(l. RBC) X (hr.) in the absence of 

 O2 , and 10 in 10% O2 . Further increase in the O2 content of the gas phase 

 to 95% results in no further reduction in K transport. This acceleration of K 

 transport by anoxia occurs when O2 is replaced by He rather than the usual 

 N2 . Thus, despite the fact that the free energy yield from anaerobic glycolysis 



Fig. 5. K influx into duck red 

 cells incubated in O2 and N2 is 

 plotted as a function of K concen- 

 tration in the medium ([Kjm). 



is only about 5% that obtained during respiration, K transport via some 

 chemical reaction pathway is considerably faster in N2 than in O2 . This sug- 

 gests that one or more of the reactions in the glycolytic pathway may be in- 

 volved in the transport of K into the duck cell. 



^») Effect of substrate. During the first hour or two after the start of the ex- 

 periment, the K transport rate is the same in duck cells incubated at 37°C in 

 the presence and absence of glucose. Furthermore, the acceleration of K trans- 

 port in N2 as compared with O2 is also observed in the absence of glucose. 

 However, if the cells are allowed to remain at 37° in N2 in the absence of glu- 

 cose for 16 to 20 hours, the K influx is reduced to i to 2% of its initial value. 

 Since this slowing of K transport occurs when the cells still contain 70-80 

 mM/1. K, K outflux must also be markedly reduced. This reduction in outflux is 

 not referable to a general decrease in the permeability of the cell to all solutes, 

 since the time required for 95% hemolysis in .3 m/1. ethylene glycol is actually 

 slightly decreased in cells which have been incubated for 20 hours as com- 



