SV matched DN and OM doses. Similar effects of DN and OM on LV SV 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) Representative PV loops at baseline (Pre) and after (Post) drug infusion. Arrows indicate the locations for measuring SV and EDV. (B and C) Quantification of the absolute change (∆) in (B) SV and (C) EDV. †P < 0.05 compared with the DMSO control group, **P < 0.01, ***P < 0.001, ns P > 0.05 as determined by ANOVA and Tukey’s HSD. Exact P values are as follows: (B) DN Low–DN High, P = 0.0044; OM Low–OM High, P = 0.0029; DN Low–OM Low, P = 1.0; DN High–OM High, P = 1.0; DMSO–DN Low, p 0.0048; DMSO–DN High, P < 1e-7; DMSO–OM Low, P = 0.012; DMSO–OM High, P < 1e-7. (C) DN Low–DN High, P = 0.00072; OM Low–OM High, P = 0.0058; DN Low–OM Low, P = 0.95; DN High–OM High, P = 1.0; DMSO–DN Low, P = 0.086; DMSO–DN High, P < 1e-7; DMSO–OM Low, P = 0.016; DMSO–OM High, P < 1e-7. Group sizes are as follows: (B) DMSO, N = 9; DN Low, N = 10; DN High, N = 10; OM Low, N = 9, OM High, N = 10. (C) DMSO, N = 9; DN Low, N = 10; DN High, N = 9; OM Low, N = 9, OM High, N = 8.