(A) Dependence of LV +dP/dt on heart rate in the different groups of animals: control uninfected sham rats (n = 6, ■), sham rats infected with Ad.βgal (n = 5, ●), sham rat hearts infected with Ad.SERCA2a (n = 4, ○), preparations from failing rat hearts infected with Ad.βgal (n = 5, ▴), and preparations of failing hearts infected with Ad.SERCA2a (n = 5, ▵ ). *, P < 0.001 compared with sham + Ad.βgal; †, P < 0.005 compared with Failing + Ad.βgal; ‡, P < 0.05 compared with Sham + Ad.SERCA2a. (B) LV pressure +dP/dt measurements at baseline and during infusion of 0.1 μg/kg/min of isoproterenol in the different groups of animals: control rats (n = 4), sham rats infected with Ad.βgal (n = 5), sham rat hearts infected with Ad.SERCA2a (n = 4), failing rat hearts infected with Ad.βgal (n = 4), and failing hearts infected with Ad.SERCA2a (n = 4). *, P < 0.001 compared with Sham + Ad.βgal; †, P < 0.005 compared with Failing + Ad.βgal.