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9-anthracene carboxylic acid is more suitable than DIDS for characterization of calcium-activated chloride current during canine ventricular action potential

Vaczi, Krisztina

Hegyi, Bence

Ruzsnavszky, Ferenc

Kistamás, Kornél

Horváth, Balázs

Bányász, Tamás

Nánási, Péter Pál

Szentandrássy, Norbert

Magyar, János

Springer

2014

RM Therapeutics. Pharmacology / terápia, gyógyszertan

Abstract
Background Understanding the role of ionic currents in shaping the cardiac action
potential (AP) has great importance as channel malfunctions can lead to sudden cardiac
death by inducing arrhythmias. Therefore, researchers frequently use inhibitors to
selectively block a certain ion channel like 4,4’-diisothiocyanostilbene-2,2’-disulfonic
acid (DIDS) and 9-anthracene carboxylic acid (9-AC) for calcium-activated chloride
current (ICl(Ca)). This study aims to explore which blocker is preferable to study ICl(Ca).
Methods Whole-cell voltage-clamp technique was used to record ICa,L, IKs, IKr and IK1,
while action potentials were measured using sharp microelectrodes. Results DIDS-
(0.2 mM) and 9-AC- (0.5 mM) sensitive currents were identical in voltage-clamp
conditions, regardless of intracellular Ca2+ buffering. DIDS-sensitive current amplitude
was larger with the increase of stimulation rate and correlated well with the rate-induced
increase of calcium transients. Both drugs increased action potential duration (APD) to
the same extent but the elevation of the plateau potential was more pronounced with
9-AC at fast stimulation rates. On the contrary, 9-AC did not influence either the AP
amplitude or the maximal rate of depolarization (Vmax) but DIDS caused marked
reduction of Vmax. Both inhibitors reduced the magnitude of phase-1 but at slow
stimulation rates this effect of DIDS was larger. All of these actions on APs were
reversible upon washout of the drugs. Increasing concentrations of 9-AC between 0.1-
0.5 mM in a cumulative manner gradually reduced phase-1 and increased APD. 1 mM
9-AC had no additional actions upon perfusion after 0.5 mM. The half-effective
concentration of 9-AC was approximately 160 ÎĽM with a Hill coefficient of 2. The
amplitudes of ICa,L, IKs, IKr and IK1 were not changed by 0.5 mM 9-AC. Conclusions These
results suggest that DIDS is equally useful to study ICl(Ca) during voltage-clamp but 9-AC
is superior in AP measurements for studying the physiological role of ICl(Ca) due to the
lack of sodium channel inhibition. 9-AC has also no action on other ion currents (ICa,L,
IKr, IKs, IK1), however, ICa,L tracings can be contaminated with ICl(Ca) when measured in
voltage-clamp condition.

angol

Article

PeerReviewed

info:eu-repo/semantics/article

text

http://real.mtak.hu/26137/1/210_2014_1050_OnlinePDF_correct...

Vaczi, Krisztina and Hegyi, Bence and Ruzsnavszky, Ferenc and Kistamás, Kornél and Horváth, Balázs and Bányász, Tamás and Nánási, Péter Pál and Szentandrássy, Norbert and Magyar, János (2014) 9-anthracene carboxylic acid is more suitable than DIDS for characterization of calcium-activated chloride current during canine ventricular action potential. NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY.

http://real.mtak.hu/26137/