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Voltage and current clamp experiments were performed on rat ventricular strips under anoxia. 1. Under the influence of anoxia the membrane depolarized by 5 to 10 mV and the action potential amplitude decreased by 15 mV. The plateau disappeared and the duration of the action potential was shortened. 2. The slow inward current was reduced by 50 to 80% and its(More)
The object of the study was to compare the capability of glibenclamide to block the effects of K(+)-ATP channel activators on action potential duration and steady state whole cell current to its efficiency in counteracting the effects of hypoxia or metabolic poisons in the presence of glycolytic substrate. The modulation of action potential duration by 30(More)
We tested the hypothesis that the early action potential shortening induced by hypoxia in perfused hearts is attributable to chloride currents activated or modulated by endogenous catecholamine release. Rabbit hearts perfused at 33 degrees C and paced at 2.5-2.8 Hz were used for membrane potential recordings with microelectrodes. Catecholamine depletion was(More)
Intracellular chloride activity (aiCl) and membrane potential (Vm) were measured in rabbit papillary muscle under in vitro conditions. The cellular chloride concentration (Cli) was estimated from measurements of total water content, extracellular space, and total chloride concentration. The effects of therapeutic (10(-8) M) and toxic (10(-6) M)(More)
STUDY OBJECTIVE The aim was to study the currents that determine the action potential duration in ventricular cells from neonatal rats. DESIGN Microelectrode measurements of action potentials from ventricle strips were compared with action potentials obtained from isolated myocytes with the whole cell patch clamp method in current clamp mode. Ionic(More)
Four different methods of measuring the resistance of a muscle fiber have been applied to the frog sartorius muscle. The methods, in which the resistance of the microelectrode entered the calculation of the effective resistance of the fiber, resulted in values which were 8 times higher than the resistance values obtained with methods independent of the(More)
1. In order to assess the role of different ionic currents in hypoxia-induced action potential shortening, we investigated the effects of blockers of voltage-dependent and ATP-sensitive K(+)-channel on the membrane potential of hypoxic rabbit hearts and papillary muscles. The response to blocking of the inward rectifier was studied at three external K+(More)