Sodium and Potassium Transport in 

 Red Blood Cells 



D. C. TOSTESON 



National Heart Institute, National Institutes 

 of Health, Bethesda, Maryland 



IN THE PAST FEW YEARS, a considerable body of new experimental data 

 bearing on the transport of sodium and potassium across the red cell 

 surface has accumulated. Several recent reviews of this information are now 

 available (60, 78, 92, 100). The present article will consider possible molecular 

 mechanisms of cation transport which are suggested by these facts. 



First, the operations by which ion transport processes may be characterized 

 will be critically analyzed. A special effort will be made to define the charac- 

 teristics which distinguish transport by diffusion from transport involving 

 chemical interaction between the ion and components of the cell membrane. 

 Those aspects of this paper which concern the diffusion of cations through the 

 red cell membrane may be regarded as extensions of the early work of Jacobs 

 on the diffusion of molecules into red cells (45). On the other hand, the sec- 

 tions dealing with the possible role of specific chemical reactions in the trans- 

 port of K and Na in red cells are clearly related to Osterhout's early studies of 

 selective K accumulation by plant cells (72). 



The criteria developed in this theoretical section of the paper will then be 

 applied to the available data on K and Na transport in the red cells of man, 

 dog and duck. There are several reasons for choosing these particular systems 

 for discussion. The red cells of man contain much K and little Na, whereas 

 those of dog are rich in Na but poor in K. It will therefore be of interest to note 

 that the detailed characteristics of K and Na transport suggest that both dif- 

 fusion and chemical reactions are involved in cation transport by the human 

 cell whereas diffusion seems to be the major mechanism in the dog cell. The 

 kinetic behavior of K in human red cells exposed to n-butanol and in the red 

 cells of subjects with sickle cell anemia (S-S) will also be examined in some de- 

 tail. In the butanol cell, diffusion appears to be the major mechanism of K 

 transport. Cation transport in S-S cells has characteristics which are inter- 

 mediate between normal cells on the one hand and butanol cells on the other. 

 Finally, the red ceils of man and duck are similar in cation composition but 

 quite different with respect to metabolism. The characteristics of cation trans- 

 port in the two systems will be contrasted in an attempt to learn about specific 



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