Influence of dexamethasone on atrial ion currents and their early ionic tachycardia-induced electrical remodeling in rabbits.
BACKGROUND
Certain evidence points to a role of inflammation in AF pathophysiology. Thus, antiinflammatory treatment of AF is discussed. Effects of a dexamethasone treatment (7 days) on atrial ion currents (I(Ca,L), I(to), I(sus)) and their tachycardia-induced remodeling were studied in a rabbit model.


METHODS
6 groups of 4 animals each were built. Rapid atrial pacing (600 min) was performed for 24 and 120 hours with/ without dexamethasone treatment. Ion currents were measured using whole cell patch clamp method.


RESULTS
Rapid atrial pacing reduced (I(Ca,L), I(to) was decreased after 24 hours but almost returned to control values after 120 hours. When dexamethasone-treated animals also underwent atrial tachypacing, pacing-induced reduction of I(Ca,L) was still observed after 24 hours and was even augmented after 120 hours compared to untreated but tachypaced animals. I(to) was not influenced by dexamethasone alone. In dexamethasone-treated animals, reduction of I(to) was not observed after 24 hours but occurred after 120 hours of atrial tachypacing. I(sus) was neither influenced by rapid atrial pacing nor by dexamethasone. Biophysical properties of all currents were affected neither by rapid atrial pacing nor by dexamethasone.


CONCLUSIONS
Dexamethasone influenced tachycardia-induced alterations of atrial I(to). Our experiments give evidence that - amongst other anti-inflammatory action - impact of dexamethasone on ion currents and their tachycardia-induced alterations might also play a role in treatment/prevention of AF with steroids.
Eberhard Karls Universität Tuebingen, Medizinische Klinik III (Kardiologie und Kreislauferkrankungen), Tübingen, Germany. roman.laszlo@gmx.de
Roman
R
Laszlo
Mareike
M
Schwiebert
Karen Anna
KA
Menzel
Birgit
B
Schreiner
Christian
C
Eick
Ralph F
RF
Bosch
Juergen
J
Schreieck
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D003907:Dexamethasone / Q000627:therapeutic use*; D055724:Electrophysiological Phenomena; D006325:Heart Atria / Q000187:drug effects / Q000503:physiopathology*; D007249:Inflammation / Q000188:drug therapy / Q000503:physiopathology; D011817:Rabbits; D013610:Tachycardia / Q000188:drug therapy* / Q000503:physiopathology; D013997:Time Factors
D000893:Anti-Inflammatory Agents; D003907:Dexamethasone