ArticleMolecular and cellular biochemistry
Early after-depolarisations induced by noradrenaline may be initiated by calcium released from sarcoplasmic reticulum.
Article in Molecular and cellular biochemistry. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
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Who cites it
4 citing papers in PubMed, 13 citations in OpenAlex.
- PCP4 regulates Purkinje cell excitability and cardiac rhythmicity.The Journal of clinical investigation · 2014Article
- Resveratrol protects rabbit ventricular myocytes against oxidative stress-induced arrhythmogenic activity and Ca2+ overload.Acta pharmacologica Sinica · 2013Article
- Cardiovascular effects of medications for the treatment of attention-deficit hyperactivity disorder: what is known and how should it influence prescribing in children?Paediatric drugs · 2010Review
- The contribution of refractoriness to arrhythmic substrate in hypokalemic Langendorff-perfused murine hearts.Pflugers Archiv : European journal of physiology · 2007Article
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2 authors at 1 institution in 1 country.
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Abstract
We investigated the effect of 10(-8) M noradrenaline (NA) on [Ca2+]i and electrical activity of single myocytes of guinea-pig ventricular myocardium loaded with Indo 1-AM. Membrane potential was recorded by means of the patch electrode and patch amplifier set to the current clamp mode. Cells were stimulated at a rate of 30/min by 3 ms pulses of the current injected through the recording electrode. Superfusion of NA resulted in slight shortening of action potentials (APs), increase in rate of rise and amplitude of the respective Ca2+ transients, and appearance of secondary Ca2+ transients of two kinds: 1. appearing before repolarisation of AP and decay of the preceding Ca2+ transient were completed and 2. appearing between the APs. We named them early after-transients (EAT) and delayed after-transients (DAT), respectively. Without any additional intervention EATs caused some prolongation of APs duration and DATs resulted in subthreshold delayed after-depolarisations (DADs). When sarcolemmal K+ conductance was decreased by tetraethylammonium (TEA) in the patch electrode or 20 microM BaCl2 in the Tyrode solution, EATs initiated early after depolarizations (EADs) and DATs initiated suprathreshold DADs triggering full-sized APs. Superfusion of 30.0 mM Na+ (replaced with LiCl) resulted in reduction of AP duration by 70% and appearance of DATs. Also, the frequent multiple oscillations of Ca2+ concentration were often observed. Neither DATs nor the oscillations had any affect on electrical activity of the cells. Their electrogenicity could not be increased by TEA or 20.0 microM Ba2+. EATs and DATs and their respective EADs and DADs could not be initiated by NA or low Na+ superfusion in the cells pretreated with 2 x 10(-7) M thapsigargin, a selective blocker of Ca(2+)-ATPase of sarcoplasmic reticulum (SR). We conclude that in contrast to the current hypothesis, EADs can be initiated by Ca2+ released early in the cardiac cycle from the overloaded SR, and that electrogenicity of both types of Ca2+ oscillations critically depends on the sarcolemmal K+ conductance.
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