Figure 2
Effects of coronary ligation on cardiorespiratory performances in coho salmon (Oncorhynchus kisutch) during sustained swimming and acute warming. Whole animal oxygen consumption rate (A,F), cardiac output (B,G), heart rate (C,H), stroke volume (D,I) and arterio-venous (A–V) O2 extraction (E,J) in coronary-ligated (blue symbols) and sham-operated (red symbols) coho salmon during routine conditions (15 °C, 0.3 body lengths s−1) or during swimming (1.5 body lengths s−1) at 15 °C or during an acute thermal challenge until the critical temperature at which fish fatigued (i.e., the functional thermal maximum, FTmax; heating rates: 15–19 °C: 4 °C h−1; 19 °C- FTmax: 1 °C h−1). The vertical dashed line indicates the onset of the thermal ramping protocol. See specific details for sample sizes (n) below each variable illustration for coronary-ligated (in blue) and sham-operated (in red) groups, n values are shared for heart rate, stroke volume and (A–V) O2 extraction. The data for coronary-ligated or sham-operated female (blue or red solid lines without symbols, respectively) and male (blue and red dashed lines without symbols, respectively) fish are depicted in each panel. The inset tables depict the outcome from the mixed models, which included the data obtained from each fish at four different levels; during routine conditions at 15 °C, swimming at 15 °C, at fatigue (i.e., FTmax) and following recovery. Only statistically significant (P ≤ 0.05) results are displayed here, see Table S1 for full disclosure of the statistical results. Asterisks (*) denote statistically significant differences between treatment groups (sham-operated vs. coronary-ligated) in cases where a significant interaction (Treatment*Level) effect was detected, hash signs (#) denote differences between sexes (male vs. female) across treatment groups (see result section for more details). For variables where a significant interaction between treatment group and experimental level (Treatment*Level) were detected (B–D), different capital and lower-case letters denote differences between the different levels within sham-operated or coronary-ligated groups, respectively. For variables where no significant Treatment*Level interaction was detected (A,E), different single lower-case letters denote differences between the different experimental levels across treatment groups. Values are means ± SEM, with the exceptions for the data from males and females, for which only means are depicted for visual clarity.
