Mario Vassalle

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The inward current ("oscillatory current") which may be present after the end of a depolarizing clamp was studied in sheep cardiac Purkinje fibers by means of a voltage-clamp method. The following results were obtained. In order to appear, the oscillatory current (Ios) requires a previous depolarization to approximately or equal to -20 mV or beyond and a(More)
VASSALEE, MARIO. Analysis of card& pacemaker potential using a %ltage clamf3 technique. Am. J. Physiol. 210(6): 1335-1341. I g66.-Diastolic depolarization was studied by means of ccvoItage clamp” technique in short mammalian Purkinje fibers. Clamping the membrane potential at the maximal diastolic value resulted in an inward current rising with a time(More)
The electrophysiological mechanisms by which changes in [K+]o suppress and initiate pacemaker activity were studied in guinea-pig isolated sino-atrial node (SAN) superfused in vitro. High [K+]o (10 mM or higher) gradually decreases maximum diastolic potential and action potential amplitude, until only subthreshold responses and eventually quiescence follow.(More)
The role of sodium and calcium ions in strophanthidin inotropy was studied by measuring simultaneously the electrical, mechanical, and intracellular sodium ion activities in electrically driven cardiac Purkinje fibers under conditions that change the intracellular sodium or calcium level (tetrodotoxin, strophanthidin, high calcium, and norepinephrine).(More)
The role of calcium in the electrical and mechanical toxicity induced by strophanthidin (10(-6) M) was studied in canine Purkinje fibers perfused in vitro. Strophanthidin caused an increase in contractile force ("therapeutic effect") followed by a subsequent decrease and by the onset of arrhythmias ("toxic effects"). The onset of arrhythmias occurred sooner(More)
1. Canine Purkinje fibres were superfused in vitro and the electrical and mechanical effects of the local anaesthetics benzocaine and procaine were studied in the absence and in the presence of other agents.2. Both benzocaine (1 x 10(-4)-5 x 10(-4)m) and procaine (6 x 10(-5)-2.5 x 10(-4)m) decreased slightly the amplitude of the upstroke and markedly the(More)