Jorge A Argibay

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1. Ca2+ currents were measured in single cells isolated from frog ventricle using the whole-cell patch clamp technique and a perfused pipette. K+ currents were blocked with intracellular (120 mM) and extracellular (20 mM) Cs+. 2. A single type of Ca2+ current (ICa) was found in these cells. The current activated at voltages positive to -30 mV, exhibited a(More)
1. The effect of ruthenium red on calcium and sodium currents was studied in guinea-pig isolated ventricular heart cells with the whole cell patch-clamp technique. 2. Ruthenium red very efficiently blocked the L-type calcium current in a dose-dependent manner. A significant block was observed for concentrations as low as 0.3 microM. Analysis of the(More)
Until recently the investigation of length-dependent effects in cardiac muscle was restricted to multicellular preparations. We describe our experimental set-up which for the first time, in single cardiac myocytes, permits the effects of changes in cell length on auxotonic contractions (measured by carbon fibre transducers) to be simultaneously recorded(More)
Single fibres from the sartorius muscle of the toad Bufo marinus were used to study ionic currents, using a fast voltage-clamp method. Sodium currents were analysed following Hodgkin-Huxley formulations. Internal caesium fluoride blocks delayed currents but produced shifts in the equilibrium potential of the early channel due to sodium accumulation. Delayed(More)
1 The possibility that the class III antiarrhythmic drugs clofilium and d-sotalol might affect delayed rectifier potassium channels at the level of their gating currents was assessed with the whole-cell patch-clamp technique in guinea-pig isolated ventricular heart cells. 2 Clofilium (up to 20 microM) and d-sotalol (1 microM) did not decrease the Na(More)
[Ca2+]i-dependent modulation of the action potential has been studied in Fura-2 dialysed ventricular myocytes of the rabbit using the whole-cell current-clamp method. Fifteen consecutive action potentials (AP1-AP15) and [Ca2+]i transients were elicited at a frequency of 0.2 Hz. A single, brief application of caffeine (during AP9) first enhanced and(More)
The effects of 100 microM ryanodine on the L-type calcium channel were studied using the pacth-clamp technique in isolated guinea pig ventricular myocytes. The inactivation kinetics of the calcium current were slowed down in the presence of ryanodine in agreement with the blockade of the release of calcium from the sarcoplasmic reticulum by the drug. The(More)
In previous work on frog atrium [11], we have shown that the carbachol-induced K current (iCCh) and the inward rectifying K channel (iK1) are both inhibited by cesium ions. A more detailed study [1, 2] indicates that the dose-response and the voltage dependence of the inhibition by Cs of iK1 and iCCh are similar. These results are in favor of a modulation(More)
1. In frog atrium, Cs ions block both the inward rectifier iK1 and the carbachol induced K current iCch. 2. Both iK1 and iCch display a high affinity for Cs with a K0.5 of 4 X 10(-5) M for iK1 and of 8 X 10(-5) M for iCch at V = -50 mV. 3. Block of both iK1 and iCch is strongly voltage dependent. When fitted by the block model of Woodhull (1973), delta is(More)
The effects of 10 mM caffeine (CAF) on intramembrane charge movements (ICM) were studied in isolated guinea-pig ventricular heart cells with the whole-cell patch-clamp technique. In the presence of CAF, the properties (voltage dependence, maximum Q(ON) [Q(max)], availability with voltage) of Q(ON) charge activated from -110 mV were barely affected.(More)