Contractile parameters in hearts from vehicle- and LPS-treated Wild-Type and A2AAR KO mice (24 h post-injection). Maximal values for left ventricular developed pressure (A) and +dP/dt (B) achieved at optimal ventricular balloon volumes of 50 μL. Inotropic state is reflected in the linear slopes of the relationships between ventricular contractile function and ventricular balloon volume (normalized to heart mass), as outlined in the Materials and methods. Slopes are shown for systolic pressure (C), and+dP/dt (D). Data are shown for Wild-Type, vehicle-treated (n = 8); Wild-Type, LPS treated (n = 9); A2AAR KO, vehicle-treated (n = 8); A2AAR KO, LPS-treated (n = 9). Data are means±S.E.M. * P<0.05 vs. corresponding vehicle value; † P<0.05 for A2AAR KO values vs. vehicle-treated Wild-Type.