Fig. 8. Effects of preload elevation on (A,C) stroke volume (VS) and (B,D) stroke work (WS) (A,B) in control conditions and (C,D) after treatment with angiotensin II (ANG II; 10^-8 mol l^-1) in isolated and perfused paced eel hearts. Percentage changes are shown as means ± S._E._M. of five experiments for each group. A paired Student's t-test was used for comparison within groups; a two-way ANOVA analysis was used for comparison between groups. (A,B) The baseline control (0 min) and the untreated time-control (30 min) values (see Materials and methods). (C,D) Values without ANG II (0 min) and with ANG II (30 min).