Related Experiment Video
Updated: Aug 14, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
Published on: July 3, 2013
Role of Ca(2+)-activated Cl(-) current in ventricular action potentials of sheep during adrenoceptor stimulation
A O Verkerk1, C A Schumacher, A C van Ginneken
1Department of Physiology, Academic Medical Center, University of Amsterdam, The Netherlands. A.O.Verkerk@amc.uva.nl
Abstract:
Adrenoceptor stimulation enhances repolarising and depolarising membrane currents to different extents in cardiac myocytes. We investigated the opposing effects of the repolarising Ca(2+)-activated Cl(-) current (I(Cl(Ca))) and depolarising L-type Ca(2+) current (I(Ca,L)) on the action potential configuration of sheep ventricular myocytes stimulated with noradrenaline. Whole-cell current-clamp recordings revealed that noradrenaline accelerated and prolonged phase-1 repolarisation. We define the minimal potential at the end of phase-1 repolarisation as "notch level". Noradrenaline (1 microM) caused the notch level to fall from 14 +/- 2.6 to 7.8 +/- 2.8 mV (n = 24), but left action potential duration, resting membrane potential or action potential amplitude unaffected. Whole-cell voltage-clamp recordings showed that 1 microM noradrenaline increased both I(Ca,L) and I(Cl(Ca)), but it had no significant effect on the principal K(+) currents. Blockage of I(Cl(Ca)) by 0.5 mM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) in both the absence and the presence of noradrenaline abolished phase-1 repolarisation. In the presence of noradrenaline, DIDS caused elevation of the plateau phase amplitude and an increase in the action potential duration. In conclusion, elevation of the plateau phase amplitude and action potential prolongation associated with an increased I(Ca,L) upon adrenoceptor stimulation is prevented by an increased I(Cl(Ca)) in sheep ventricular myocytes. Experimental Physiology (2001) 86.2, 151-159.
Related Concept Videos
G-Protein Gated Ion Channels
Sensory organs,...
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Antihypertensive Drugs: Action of Calcium Channel Blockers
Electrophysiology of Normal Cardiac Rhythm
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials

