TPEN prevents rapid pacing-induced calcium overload and nitration stress in HL-1 myocytes.

INTRODUCTION

Atrial fibrillation (AF) is the most common cardiac arrhythmia. However, the current drug interference of antiarrhythmia has limited efficacy and off-target effects. Accumulating evidence has implicated a potential role of nitration stress in the pathogenesis of AF. The aim of the study was to determine whether TPEN provided antinitration effects on atrial myocytes during AF, especially under circumstances of nitration stress.

METHODS

We utilized a rapid paced HL-1 cells model for AF. The changes of electrophysiological characteristics and structure of paced HL-1 cells were determined by a patch clamp and a TEM method. The effects of TPEN on pacing and ONOO(-) pretreated HL-1 cells were examined using MTT assay, TUNEL technique, confocal microscope experiment, and Western blot analysis.

RESULTS

The results revealed that ONOO(-) reduced the viability of HL-1 cells in a dose-dependent manner, and 1 μmol/L TPEN significantly ameliorated the damage caused by 50 μmol/L ONOO(-) (P < 0.05). Pacing and/or ONOO(-) -induced marked shortening of APD, myolysis, and nuclear condensation. TPEN inhibited the Ca(2+) overload induced by rapid pacing (P < 0.05) and ONOO(-) stimulation (P < 0.05). The application of TPEN significantly prevented the protein nitration caused by pacing or pacing plus ONOO(-) (P < 0.05). Additionally, pacing in combination with ONOO(-) treatment led to increase in apoptosis in HL-1 cells (P < 0.01), which could be reduced by pretreatment with TPEN (P < 0.05).

CONCLUSIONS

TPEN prevents Ca(2+) overload and nitration stress in HL-1 atrial myocytes during rapid pacing and circumstances of nitration stress.