Fig. 3. Concentration–response curve for the effects of synthetic EI-14 on atrial beating. (A) The change in contractile force after addition of EI-14 plotted against its corresponding concentration (logarithmic scale). The control value before addition of EI-14 was 14.34±1.95mN (N=13). Values are means ± S.E.M. The number of experiments at each concentration is indicated in parentheses. (B) The effect of EI-14 on atrial beating rate. The control value was 69.5±6.6beatsmin^-1 (N=13). The sample size is the same as in A.