Vehicle control and other DN continuous infusion experiments. (A and B) LV pressure response to a continuous infusion of either (A) vehicle control (DMSO) at 75 μl/kg/min or (B) DN at 3 mg/kg/min parameterized by the maximum LV pressure (P_max), minimum LV pressure (P_min), the maximum rate of LV pressure change (dP/dt_max), and minimum rate of LV pressure change (dP/dt_min). The x axis represents the cumulative infused dose. The two observed phases of the LV pressure response (P1 and P2) are marked with dashed lines.