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Sarcolemmal Ca 2+ -entry through L-type Ca 2+ channels controls the profile of Ca 2+ -activated Cl − current in canine ventricular myocytes
Sarcolemmal Ca 2+ -entry through L-type Ca 2+ channels controls the profile of Ca 2+ -activated Cl − current in canine ventricular myocytes
- Source :
- Journal of Molecular and Cellular Cardiology. 97:125-139
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- Ca 2+ -activated Cl − current (I Cl(Ca) ) mediated by TMEM16A and/or Bestrophin-3 may contribute to cardiac arrhythmias. The true profile of I Cl(Ca) during an actual ventricular action potential (AP), however, is poorly understood. We aimed to study the profile of I Cl(Ca) systematically under physiological conditions (normal Ca 2+ cycling and AP voltage-clamp) as well as in conditions designed to change [Ca 2+ ] i . The expression of TMEM16A and/or Bestrophin-3 in canine and human left ventricular myocytes was examined. The possible spatial distribution of these proteins and their co-localization with Ca v 1.2 was also studied. The profile of I Cl(Ca), identified as a 9-anthracene carboxylic acid-sensitive current under AP voltage-clamp conditions, contained an early fast outward and a late inward component, overlapping early and terminal repolarizations, respectively. Both components were moderately reduced by ryanodine, while fully abolished by BAPTA, but not EGTA. [Ca 2+ ] i was monitored using Fura-2-AM. Setting [Ca 2+ ] i to the systolic level measured in the bulk cytoplasm (1.1 μM) decreased I Cl(Ca), while application of Bay K8644, isoproterenol, and faster stimulation rates increased the amplitude of I Cl(Ca) . Ca 2+ -entry through L-type Ca 2+ channels was essential for activation of I Cl(Ca) . TMEM16A and Bestrophin-3 showed strong co-localization with one another and also with Ca v 1.2 channels, when assessed using immunolabeling and confocal microscopy in both canine myocytes and human ventricular myocardium. Activation of I Cl(Ca) in canine ventricular cells requires Ca 2+ -entry through neighboring L-type Ca 2+ channels and is only augmented by SR Ca 2+ -release. Substantial activation of I Cl(Ca) requires high Ca 2+ concentration in the dyadic clefts which can be effectively buffered by BAPTA, but not EGTA.
- Subjects :
- 0301 basic medicine
Patch-Clamp Techniques
Calcium Channels, L-Type
Stereochemistry
Heart Ventricles
Action Potentials
Cav1.2
Ventricular action potential
03 medical and health sciences
chemistry.chemical_compound
Dogs
BAPTA
Chloride Channels
Animals
Humans
Myocyte
Myocytes, Cardiac
Elméleti orvostudományok
Molecular Biology
biology
Ryanodine receptor
Orvostudományok
Calcium Channel Blockers
Bay K8644
Electrophysiological Phenomena
Sarcoplasmic Reticulum
EGTA
030104 developmental biology
chemistry
DIDS
Biophysics
biology.protein
Cardiology and Cardiovascular Medicine
Biomarkers
Subjects
Details
- ISSN :
- 00222828
- Volume :
- 97
- Database :
- OpenAIRE
- Journal :
- Journal of Molecular and Cellular Cardiology
- Accession number :
- edsair.doi.dedup.....9552b492f6e0552b06332cb91deba7c0
- Full Text :
- https://doi.org/10.1016/j.yjmcc.2016.05.006