Cytochalasin D at 5 or 10 micromoles prolonged APD90 (up to 177 msec vs 131 msec control), steepened APDR slope, and reduced dominant frequency in rabbit ventricles (P < 0.01).
Does cytochalasin D alter action potential duration restitution and ventricular fibrillation dynamics in isolated rabbit hearts?
Cytochalasin D, commonly used as an excitation-contraction uncoupler in optical mapping, significantly alters electrophysiological properties including APD restitution and VF dynamics in rabbit hearts.
p-value: p=< 0.01
UNLABELLED: Cytochalasin D in Rabbit Ventricle. INTRODUCTION: Cytochalasin D (cyto-D) has been used as an excitation-contraction uncoupler during optical mapping studies. However, its effects on action potential duration restitution (APDR) and dynamics during ventricular fibrillation (VF) are unclear. METHODS AND RESULTS: Langendorff-perfused rabbit hearts (N = 6) were immersed in a tissue chamber. Transmembrane potential was recorded using glass microelectrodes. APD measured to 90% repolarization (APD90) was used to construct the APDR curve. During regular pacing at 300-msec cycle length, increasing concentrations of cyto-D resulted in progressively prolonged APD90 (131 +/- 26 msec, 171 +/- 14 msec, and 177 +/- 14 msec) and steepened maximum slope of the APDR curve (1.1 +/- 0.2, 1.3 +/- 0.2, and 1.6 +/- 0.4 for control, 5 micromoles, and 10 micromoles, respectively; P 1 min) VF was repeatedly inducible at baseline and with 5 or 10 micromoles of cyto-D. CONCLUSION: Continuous perfusion of cyto-D at 5 or 10 micromoles prolonged APD90, steepened APDR slope, and reduced dominant frequency in rabbit ventricles. Cyto-D at these concentrations allowed induction of sustained VF.
Hayashi et al. (Fri,) conducted a other in Ventricular fibrillation (n=6). Cytochalasin D vs. Control was evaluated on Action potential duration to 90% repolarization (APD90) and maximum slope of the APDR curve (p=< 0.01). Cytochalasin D at 5 or 10 micromoles prolonged APD90 (up to 177 msec vs 131 msec control), steepened APDR slope, and reduced dominant frequency in rabbit ventricles (P < 0.01).