To avoid inadvertently perturbing the ATP level of the frog muscle at the same time, we added an extremely low concentration of an electron-donating cardinal adsorbent (EDC) a cardiac drug called ouabain 37 to the bathing solution containing an increasing ratios of the concentration of K+ over Na+. All the data points in Figure 9 are experimental and the pairs of X-shaped curves are once more theoretical according to the Yang-Ling isotherm. What the drug did was to reduce the value of Kooj→I from 100 to 21.7. The result shows that at the physiological concentration ratio of 2.5 x 10-2, the entire population of β-, and γ-carboxyl groups changed its adsorption partners from all K+ to all Na+.