FIGURE 3.

Inhibition of digoxigenin and n-digitoxide digoxigenin (n = 1–4). A, inhibition curves at pH 7.5. ▿, digoxigenin, K_i = 194 nm; ○, digoxigenin monodigitoxide, K_i = 131 nm; □, digoxigenin didigitoxide, K_i = 137 nm; ♢, digitoxigenin tridigitoxide (digoxin), 115 nm; ▵, digoxigenin tetradigitoxide, K_i = 203 nm. B, K_i values for the different CTS compounds at pH 6.5 (▵), 7.5 (○), and 8.5 (□). Mean K_i values calculated from fitting to the sigmoid dose-response equation are given in Table 1. Error bars, S.E.