Figure 3: Maximal rates of left ventricular pressure development and relaxation (±dP/dtmax) and time from peak to 75% relaxation (TR75) of left ventricular pressure. (a) and (c) ±dP/dtmax and TR75 under different rates of pacing. (b) and (d) ±dP/dtmax and TR75 in different concentrations of ISO treatment. Data are mean ± SEM, hearts for each ISO concentration in each group. * or ** versus baseline.