Figure 6.

Effects of apamin on the maximal slope of APDR curve in HF and normal ventricles. A, APDR curves and maximal slopes of the curves sampled at a basal (site a), a middle (site b), and an apical (site c) area of a failing left ventricle. Lower panel showed the APD₈₀ before (blue line) and after (red line) apamin infusion at site a. Note that apamin prolonged APD₈₀ at very long (350 and 300 ms) and short (160 ms) PCLs. As a result, it steepened the APDR at long PCL and flattened the APDR at short PCL. B, APDR curves and maximal slopes of the curves in a normal left ventricle. Lower panel showed the APD changed by apamin at site a. C and D, effects of apamin on the maximal slopes of APDR in HF and normal ventricles. Note that HF ventricles at baseline have higher maximal slopes than normal ventricles (asterisk in C). Apamin decreased the maximal slope in HF ventricles, but did not change the slope in normal ventricles. The small squares in the data box indicate the mean value. LAD, left anterior descending coronary artery; RV, right ventricle; LV, left ventricle.