Electrophysiological effects of tamoxifen: mechanism of protection against reperfusion arrhythmias in isolated rat hearts.

Reperfusion arrhythmias are currently attributed to ionic imbalance and oxidative stress. Tamoxifen is a potent antioxidant that also modulates some ionic transport pathways. In this work, we tried to correlate the electrophysiological effects of 1, 2, and 5 µM of tamoxifen with the incidence and severity of arrhythmias appearing on reperfusion after 10 minutes of coronary occlusion in isolated hearts from female rats.

Effects of barium and 5-hydroxydecanoate on the electrophysiologic response to acute regional ischemia and reperfusion in rat hearts.

The aim of this work was to investigate the role of the inward rectifying (K1) and the sarcolemmal ATP-sensitive K+ (K-ATP) channels in the electrical response to regional ischemia and the subsequent development of ventricular tachyarrhythmias on reflow (RA). Surface electrograms (ECG) and the transmembrane potential from subepicardial left ventricular cells were recorded in spontaneously beating rat hearts perfused with buffer alone (controls) or exposed to 100 microM BaCl2 or 100 microM 5-hydroxydecanoate (5-HD) to block either K1 or K-ATP channels respectively. After 20 min of equilibration and 10 min of control recordings, the left anterior descending coronary artery was occluded for 10 min.

4-Aminopyridine: effects on electrical activity during ischemia and reperfusion in perfused rat hearts.

We investigated the effects of 2 and 4 mM 4-aminopyridine (4-AP,--blocker of the transient outward current I(to) on the electrophysiological response to regional ischemia and reperfusion. Spontaneously beating rat hearts were subjected to coronary occlusion (10 min) followed by reperfusion. The surface electrogram and the membrane potential from subepicardial left ventricular cells were recorded throughout.

Differential electrophysiologic effects of global and regional ischemia and reperfusion in perfused rat hearts. Effects of Mg2+ concentration.

The effects of regional and global ischemia on cellular electrical activity and on arrhythmias induced by reperfusion were studied at different Mg2+ concentrations (Mg2+o, 0, 1.2, and 4.8 mM) in perfused rat hearts.

Background K+ currents and response to metabolic inhibition during early development in rat cardiocytes.

The effects of metabolic inhibition on K+ background currents and action potential duration were investigated in neonatal rat ventricle cells during early development. Action potentials and ionic currents were measured with the patch clamp technique in current and voltage clamp mode in cells isolated with collagenase from 1 day and 7 day old rats. During the first postnatal week, the cell surface increased from 1700 to 2210 microm2 and the membrane hyperpolarized from -66.