Figure 1. Linear relationship between the time constant of isovolumic relaxation (tau) and left ventricular end-systolic pressure (Pes) during inferior vena caval occlusion (left panels) in a typical dog before (grey squares) and after (solid squares) the development of pacing-induced cardiomyopathy in the conscious state (top panel, tau = 0.29 x Pes+ 2.2; r2= 0.99 before compared with tau = 0.86 x Pes- 37.0; r2= 0.98 after pacing) and during isoflurane (middle panel, tau = 0.26 x Pes+ 12.6; r2= 0.98 before compared with tau = 1.14 x Pes- 25.7; r2= 0.99 after pacing) and halothane (bottom panel, tau = 0.27 x Pes+ 20.9; r2= 0.98 before compared with tau = 1.25 x Pes- 11.3; r2= 0.99 after pacing) anesthesia. The histograms on the right illustrate the slope (R) the tau versus Pesrelationship in the conscious state (top right panel) and during isoflurane (middle right panel) and halothane (bottom right panel) anesthesia before (hatched bars) and after pacing (solid bars).aSignificantly different from normal myocardium.