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Tetrodotoxin (TTX) shortens Purkinje fiber action potential duration (APD) at concentrations (greater than or equal to 3.3 x 10(-8) M) lower than that at which the maximum rate of rise decreases (approximately 10(-6) M). The shortening effect of TTX occurs either at low or high driving rate and is much greater in Purkinje fibers than in bundle branch and(More)
Ventricular hypertrophy is associated with an increase in action potential (AP) plateau amplitude and duration. In a model of cardiac hypertrophy by DOCA-pellet implantation in uninephrectomized saline-drinking rats, we have previously demonstrated that the influence of hypertrophy was to reduce Ito1 density, the process being fully reversible after(More)
1. The whole-cell voltage-clamp technique was applied to isolated rat ventricular myocytes to investigate the effects of D600 (10(-9)-10(-3) M) on the intracellular calcium-independent component of transient outward current. I(lo), recorded in a sodium-free medium containing 0.5 x 10(-3) M-cadmium and 10(-6) M-ryanodine. 2. Externally applied D600 reduced(More)
Recent evidence has suggested a major role for a slowly inactivating component of Na(+)current (I(NaL)) as a contributor to ischemic Na(+)loading. The purposes of this study were to investigate veratrine and lysophosphatidylcholine (LPC)-induced I(NaL)in single ventricular myocytes of normal and diabetic rats and to analyse the effects on this current of(More)
The effect of 2,3-butanedione 2-monoxime (BDM), a substance possessing phosphatase-like activity, was studied on action potentials of isolated rat heart and on the slow inward calcium current and outward current (including the 4-aminopyridine (4-AP)-sensitive transient outward component), in rat ventricular myocytes. In contrast to what was observed by(More)
It has been suggested in a previous article [Escande et al., Am. J. Physiol. 249 (Heart Circ. Physiol. 18): H843-H850, 1985] that transient outward currents may participate in the initial repolarization of human atrial fibers. The present study substantiates the existence of such currents in human myocardium. Membrane currents were recorded in enzymatically(More)
The slow inward current isi plays a prominent role in impulse formation and slow conduction in the human heart. For this reason, it may be involved in a great variety of arrhythmias that occur clinically, particularly at the supraventricular level. isi also appears to be the major target of numerous cardioactive drugs daily administered to many patients.(More)
OBJECTIVE The aim of our study was to determine the main electrophysiological alterations associated with cardiac dilation in MS200 strain Syrian hamsters, a model of genetically determined cardiomyopathy. METHODS Ventricular action potentials (APs) were recorded with standard microelectrodes in isolated hearts from 120-day-old cardiomyopathic (strain(More)
The present study demonstrates that background or B-type calcium channel activity can be recorded in excised inside-out and cell-attached membrane patches from human atrial myocytes. In control conditions, with Ba2+ or Ca2+ as charge carrier, single-channel activity spontaneously appeared in irregular bursts separated by quiescent periods of 2-17 min, in(More)