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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 resting potential and the intracellular Na and K concentrations (Nai, Ki) were determined at several extracellular K concentrations (Ko) between 0.5 and 18 mM and after inhibition of the sodium pump with 0.5 microM ouabain. Exposure to low Ko (0.5 mM) produced a transient hyperpolarization (from -80 to -100 mV) followed by a depolarization that led to a(More)
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(More)
We studied in whole cell configuration with the patch clamp method the effect of taurine on the macroscopic Na current in adult ventricular rabbit myocytes. Because these cells have a large surface [13,750 +/- 704 microns2 (19), mean +/- S.E.M. (n)], we reduced [Na]o to 45 mM and worked at room temperature to obtain acceptable voltage control. When the(More)
In rat ventricular muscle, measurements of the membrane potential with microelectrodes during depolarizing voltage steps showed that deviation of the membrane potential from the command signal were never larger than 15 mV during flow of the fast inward current and that voltage control was regained within 15 ms after the beginning of the voltage step. During(More)
The spontaneous activity of cell clusters derived from ventricle cells of newborn rats was studied using a recording television microscope. The influence of varying concentrations of sodium, potassium, calcium, tetrodotoxin (TTX), and that of 2 mM MnCl2 was tested. The spontaneous activity of the cell clusters persisted in TTX but it was abolished by Mn.(More)
Spontaneously active explanted rat ventricle cells show 4 to 7 h after explantation fast rising TTX sensitive action potentials but 24 h after explantation, electrogenesis is determined by slow rising. Mn sensitive action potentials. Because 4 to 7 h after explantation the electrical properties of the cells resemble more those of the tissue they were(More)
We compared the passive electrical properties of isolated ventricular myocytes (resting potential -65 mV, fast action potentials, and no spontaneous activity) with those of 2- to 7-day-old cultured ventricle cells from neonatal rats (resting potential -50 mV, slow action potentials, and presence of spontaneous activity). In myocytes the specific membrane(More)
Spontaneously beating explanted neonatal rat ventricle cells stop beating and show a steady potential (the mean resting potential, -46.2 mV at 6.0 mM Ko) when exposed to 10 mM Cao or 4 mM Mn. When Ko was increased, resting potential changed only slightly between 3 and 15 mM, but the resting potential versus Ko characteristically approached the slope of a K(More)
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