290 



C. T. GAFFEY 



Radii Hydration energy 

 /j^ \ (^) (kcal/Mole) 



...4.05 34.5 



-2 6.77 16.3 



-3- 9.49 6.9 



J -...12.21 3.9 



5-^00 ...00 13.9 



Fig. 11. Representation of the potassium ion with a crystalline radius of 1.33 A 

 and the 1st, 2nd, 3rd, and 4th hydration shells. The diameter of a water layer is 

 taken as 2.72 A. Hydration energies for a given hydration shell are computed on the 

 basis that hydration energy exponentially decreases with the distance from the charge 

 on the ion. 



Hydration energy 

 ^r-x \ Radii (A) (kcol/Mole ) 

 (I^-... J.... 0.95 



X-^. 3.67 49.8 



_2._ 6.39 19.0 



-3.-- 9.11 77 



J*.- 11.83 4.1 



5-*-oo 00 13.9 



Fig. 12. Representation of the sodium ion with a crystalline radius of 0.95 A and 

 the 1st, 2nd, 3rd, and 4th hydration shells. 



est relative membrane permeability, potassium (see Fig. 13, resting state). 

 The spread of the Gaussian distribution curve for the resting state is adjusted 

 so the area representing potassium ion channel is 25 times greater than the 

 area representing sodium ion channels, which is in harmony with Hodgkin 

 and Katz's (1949) evidence that the relative permeability of potassium to 



