(A) Experimental protocol. All animals were divided into five groups, and the LCA was not tightened: vehicle (Vh [PBS]) for 5HD or HMR1098 and pinacidil (Pin), 5HD and Pin, HMR1098 and Pin, vehicle (PBS) for 5HD or HMR1098 and vehicle (PBS) for pinacidil (Vh and Vh), and glibenclamide (Gli) and Pin. The guinea pig was intravenously injected in the right jugular vein with PBS (100 µL), 5-HD (3 mg/kg [100 µL]), HMR1098 (4 mg/kg [100 µL]) or glibenclamide (4 mg/kg [100 µL]), according to their respective grouping 14–15 min before pinacidil (0.45 mg/kg [100 µL]) or PBS (100 µL) was locally injected into the left ventricular area. (B) Representative electrocardiographic recordings. (C) Summary percent of control of ST/QRS+ at different time points for each group. Data are mean ± SEM from five animals per group. *P< 0.05, Gli + Pin group versus 5HD + Pin group, PBS + PBS group, and PBS + Pin group. #P < 0.05, 5HD + Pin group versus HMR1098 + Pin group.