Effects of diacetyl monoxime and cytochalasin D on ventricular fibrillation in swine right ventricles

Abstract

Whether or not the excitation-contraction (E-C) uncoupler diacetyl monoxime (DAM) and cytochalacin D (Cyto D) alter the ventricular fibrillation (VF) activation patterns is unclear. We recorded single cell action potentials and performed optical mapping in isolated perfused swine right ventricles (RV) at different concentrations of DAM and Cyto D. Increasing the concentration of DAM results in progressively shortened action potential duration (APD) measured to 90% repolarization, reduced the slope of the APD restitition curve, decreased Kolmogorov-Sinai entropy, and reduced the number of VF wave fronts. In all RVs, 15-20 mmol/l DAM converted VF to ventricular tachycardia (VT). The VF could be reinduced after the DAM was washed out. In comparison, Cyto D (10-40 micromol/l) has no effects on APD restitution curve or the dynamics of VF. The effects of DAM on VF are associated with a reduced number of wave fronts and dynamic complexities in VF. These results are compatible with the restitution hypothesis of VF and suggest that DAM may be unsuitable as an E-C uncoupler for optical mapping studies of VF in the swine RVs.

Pharmacological Blockade of <I>I</I><SUB>Ks</SUB> Destabilizes Spiral-Wave Reentry Under <I>&beta;</I>-Adrenergic Stimulation in Favor of Its Early Termination

“…These characteristics deviate from those observed in our previous studies in a similar rabbit 2-dimensional ventricular myocardium in the presence of BDM, where VTs were more stable and lasted longer (VTs lasting > 30 s were 17% -29%) (18,19). The slope of APD restitution of ventricular muscle, which is known to determine the stability of wavefronts during functional reentry (33), was shown to be reduced significantly by BDM in favor of its stabilization, whereas unaffected or increased by cytochalasin D (22,34). VTs induced after single treatment with ISP were more stable and lasted longer than without ISP.…”

“…In the present study, VTs were induced by modified cross-field stimulation in the presence of cytochalasin D as an excitation-contraction uncoupler, since modification of steady-state and dynamic action potential configu- ISP ration in cardiac cells by this compound is much less than that by 2,3-butanedione monoxime (BDM) (22). The VTs induced under control conditions were unstable and terminated soon (VTs lasting > 5 s were only 3%).…”

“…The acquired image covered the anterolateral surface (30 × 30 mm) of the left ventricle (LV). To reveal the action potential signal, the background fluorescence was subtracted and low-pass filtering was applied (22). Spatial resolution after filtering was 0.1 mm.…”

Combined Effects of Nifekalant and Lidocaine on the Spiral-Type Re-Entry in a Perfused 2-Dimensional Layer of Rabbit Ventricular Myocardium

“…16 A time point at 10% depolarization in the upstroke phase and a time point at 90% repolarization in its repolarization phase were identified for each action potential signal, and their interval was measured as APD at 90% repolarization (APD90). The distribution of APD90 values in the recording area was displayed as color gradient maps with 1.33 ms steps ranging from red (the shortest) to blue (the longest).…”

The Photodiode Array: A Critical Cornerstone in Cardiac Optical Mapping

“…Electromechanical uncouplers work by a variety of methods, but most have an effect upon the actin-myosin cytoskeleton which is responsible for contraction. Electromechanical uncouplers should be used with care, as some studies have shown that these agents can affect various parameters of the cardiac AP and may also affect the dynamics of ventricular fibrillation (VF) (Baker et al, 2004;Biermann et al, 1998;Hyashi et al, 2003;Lee et al, 2001). …”