Membrane potential was changed uniformly in segments, 0.7-1.0 mm long, of guinea pig papillary muscles excised from the right ventricle by using extracellular polarizing current pulses applied across two electrically insulated cf preparations superfused with Tyrode's solution at maximum diastolic membrane potentials ranging from-35.2+/-7.5 (threshold) to +4.0+/-9.2 mV. The average maximum dV/dt of RAD ranged from 17.1 to 18.0 V/sec within a membrane potential range of -40 to +20 mV. Raising extracellular Ca2+ concentration [Ca2+]0 from 1.8 to 6.8 mM, or application of isoproterenol (10(-6)g/ml) enhanced the rate of RAD, but lowering [Ca2+]0 to 0.4 mM or exposure to MnCl2 (6 mM) abolished RAD. RAD were enhanced by lowering extracellular K+ concentration [K+]0 from 5.4 to 1.5 mM. RAD were suppressed in 40% of fibers by raising [K+]0 to 15.4 mM, and in all fibers by raising [K+]0 to 40.4 mM. This suppression was due to increased [K+]0 and not to K-induced depolarization because it persisted when membrane potential was held by means of a conditioning hyperpolarizing puled gradually after maximum repolarization. These observations suggest that the development of RAD in depolarized myocardium is associated with a time-dependent decre...Continue Reading
Extracellular potassium accumulation and inward-going potassium rectification in voltage clamped ventricular muscle
Some limitations of the double sucrose gap, and its use in a study of the slow outward current in mammalian ventricular muscle
Characterization and localization of ventricular arrhythmias resulting from myocardial ischemia and infarction
The effect of resting potential on the electrical activity of canine cardiac Purkinje fibers exposed to Na-free solution or to ouabain
Electrical and mechanical responses from ventricular muscle fibers after inactivation of the sodium carrying system
Effects of low and high concentrations of potassium on the simultaneously recorded Purkinje and ventricular action potentials of the perfused pig moderator band
Electrical and mechanical activity of mammalian heart fibres treated with papaverine. Interaction with isoprenaline and dibutyryl cyclic AMP
Effect of Bay K8644 on cytosolic calcium transients and contraction in embryonic cardiac ventricular myocytes
Effects of amiloride on the mechanical, electrical and biochemical aspects of ischemia-reperfusion injury
Role of neurotransmitter release and cyclic AMP-dependent membrane phosphorylation in low voltage myocardial automaticity
Role of the Inward K Rectifier in the Repetitive Activity at the Depolarized Level in Single Ventricular Myocytes
Antiarrhythmic evaluation of verapamil, nifedipine, perhexiline and skf 525-A in four canine models of cardiac arrhythmias
Electrophysiologic substrate of torsade de pointes: dispersion of repolarization or early afterdepolarizations?
Autonomic and antiarrhythmic drug modulation of ST segment elevation in patients with Brugada syndrome
Contribution of depolarized foci with variable conduction impairment to arrhythmogenesis in 1 day old infarcted canine cardiac tissue: an in vitro study
Cesium blockade of delayed outward currents and electrically induced pacemaker activity in mammalian ventricular myocardium
Repolarization of the cardiac action potential. Does an increase in repolarization capacity constitute a new anti-arrhythmic principle?
Mechanisms underlying sustained firing from pulmonary veins: evidence from pacing maneuvers and pharmacological manipulation
Facilitation of beta-adrenoceptor-mediated slow channel responses by hypoxia in guinea pig ventricular myocardium
Ectopic ventricular tachycardia sensitive to calcium antagonists in acute myocardial infarction in dogs
Barium-induced nondriven action potentials as a model of triggered potentials from early afterdepolarizations: significance of slow channel activity and differing effects of quinidine and amiodarone
Computer analysis of exercise-induced changes in QRS duration in patients with angina pectoris and in normal subjects
Can accelerated atrioventricular junctional escape rhythms be explained by delayed afterdepolarizations?
Electrophysiological changes and ventricular arrhythmias in the early phase of regional myocardial ischemia
An evaluation of automaticity and triggered activity in the canine heart one to four days after myocardial infarction
Contribution of variable entrance and exit block in protected foci to arrhythmogenesis in isolated ventricular tissues
Effects of K+ and K+-induced polarization on (dV/dt)max, threshold potential, and membrane input resistance in guinea pig and cat ventricular myocardium
Cardiac electrophysiology is the study of electrical activities of the heart and includes the assessment, diagnosis, and treatment of cardiac events. Find the latest research on cardiac electrophysiology here.