Bolus responses to DN and OM measured by steady-state LV–PV loops. Analysis of LV pressure and volume signals 1 min after infusion of either vehicle control (DMSO), DN at 3 mg/kg (DN Low), DN at 6 mg/kg (DN High), OM at 0.75 mg/kg (OM Low), or OM at 1.5 mg/kg (OM High). (A and B) Representative LV pressure and (B) volume waveforms at baseline (Pre) and after (Post) drug infusion. Panels are annotated with where the systolic duration, time constant of pressure relaxation (Tau), maximum rate of pressure development (dP/dtmax), and PER measurements are taken. (D–F) Quantifications of the absolute change (∆) in (C) dP/dtmax, (D) systolic duration, (E) PER, and (F) Tau. †P < 0.05 compared with the DMSO control group, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, ns P > 0.05 as determined by ANOVA and Tukey’s HSD. Exact P values are as follows: (C) DN Low–DN High, P = 0.0032; OM Low–OM High, P = 0.049; DN Low–OM Low, P = 1.0; DN High–OM High, P = 0.95; DMSO–DN Low, P = 0.049; DMSO–DN High, P < 1e-7; DMSO–OM Low, P = 0.046; DMSO–OM High, P = 1.2e-5. (D) DN Low–DN High, P = 0.0001; OM Low–OM High, p < 1e-7; DN Low–OM Low, P = 0.043; DN High–OM High, P = 2.5e-5; DMSO–DN Low, P = 0.35; DMSO–DN High, P < 1e-7; DMSO–OM Low, P = 0.00024; DMSO–OM High, P < 1e-7. (E) DN Low–DN High, P = 0.0034; OM Low–OM High, P = 0.99; DN Low–OM Low, P = 0.51; DN High–OM High, P = 0.00015; DMSO–DN Low, P = 0.23; DMSO–DN High, P = 1e-5; DMSO–OM Low, P = 0.98; DMSO–OM High, P = 0.81. (F) DN Low–DN High, P = 2.6e-5; OM Low–OM High, P < 1e-7; DN Low–OM Low, P = 0.65; DN High–OM High, P = 9.6e-6; DMSO–DN Low, P = 0.29; DMSO–DN High, P < 1e-7; DMSO–OM Low, P = 0.012; DMSO–OM High, P < 1e-7. Group sizes are as follows: (C) DMSO, N = 8; DN Low, N = 10; DN High, N = 9; OM Low, N = 8, OM High, N = 8. (D) DMSO, N = 9; DN Low, N = 11; DN High, N = 10; OM Low, N = 10, OM High, N = 10. (E) DMSO, N = 7; DN Low, N = 10; DN High, N = 8; OM Low, N = 10, OM High, N = 10. (F) DMSO, N = 9; DN Low, N = 10; DN High, N = 8; OM Low, N = 10, OM High, N = 10.