Non-uniform prolongation of intracellular Ca transients recorded from the epicardial surface of isolated hearts from rabbits with heart failure

ObjectiÕes: To study the time course of Ca transients recorded from the left ventricular epicardial surface of isolated hearts from rabbits with heart failure and to correlate the results with mechanical function. Methods: Heart failure was induced in the rabbit 8 weeks Ž . after coronary ligation ns17 with 13 controls. Echocardiography was used to assess in vivo left ventricular dysfunction. The fluorescent indicator Indo-1 was loaded into isolated Langendorff-perfused hearts and Ca transients were recorded from 15 sites over the left ventricular epicardial surface using a single core light guide. The time course of the Ca transients was analysed and the duration measured and correlated with in vitro mechanical function. Results: Significant mechanical dysfunction was produced in this model of 2q Ž . heart failure. The mean duration of the Ca transients obtained from failing hearts was prolonged 156.2"3.2 ms when compared to Ž . controls 124.9"2.6 ms, P-0.001 . Delayed relaxation as measured by the maximum rate of intraventricular pressure decay was 2q Ž . significantly correlated with the prolonged Ca transients rsy0.63, P-0.001 . In addition, there was increased variation of the Ca transient duration in the failing hearts. Conclusions: Coronary artery ligation-induced heart failure is associated with changes in the surviving myocardium which result in a non-uniform prolongation of Ca transient duration. This suggests that there is a regional heterogeneity to the abnormal intracellular Ca handling in heart failure. q 1998 Elsevier Science B.V. w 2q x 2q