Electrophysiological Effects of Triggered Calcium Waves on the Action Potential in Left Atrial Myocytes from Normal and Failing Dog Heart

We previously reported that triggered Ca waves (TCWs) occur in dog atrial myocytes during rapid pacing. The goal of this study was to investigate the effect of TCWs on APs during rapid pacing in left atrial myocytes from both normal and failing hearts (rapid RV pacing model). Intracellular Ca and AP recordings were made in atrial myocytes isolated from normal and failing (HF) dog hearts loaded with Ca-sensitive fluorescent dyes and stimulated at increasingly rapid rates (1-5Hz). Both normal and HF atrial myocytes developed TCWs which increased action potential duration (APD) and reduced maximum diastolic potential (MDP) throughout the duration of each TCW.