Rapid pacing of embryoid bodies impairs mitochondrial ATP synthesis by a calcium-dependent mechanism -: A model of in vitro differentiated cardiomyocytes to study molecular effects of tachycardia

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1762

Article

Schild, Lorenz ; Bukowska, Alicja ; Gardemann, Andreas ; Polczyk, Pamela ; Keilhoff, Gerburg ; Taeger, Michael ; Dudley, Samuel C. ; Klein, Helmut U. ; Goette, Andreas ; Lendeckel, Uwe

关键词: arrhythmia;    hypertrophy;    myocyte;    oxidative stress;    pacing;    mitochondria;   

DOI  :  10.1016/j.bbadis.2006.03.005

来源: Elsevier

【 摘 要 】

Tachycardia may cause substantial molecular and ultrastructural alterations in cardiac tissue. The underlying pathophysiology has not been fully explored. The purpose of this study was (I) to validate a three-dimensional in vitro pacing model, (II) to examine the effect of rapid pacing on mitochondrial function in intact cells, and (III) to evaluate the involvement of L-type-channel-mediated calcium influx in alterations of mitochondria in cardiomyocytes during rapid pacing. In vitro differentiated cardiomyocytes from PI9 cells that formed embryoid bodies were paced for 24 h with 0.6 and 2.0 Hz. Pacing at 2.0 Hz increased mRNA expression and phosphorylation of ERK1/2 and caused cellular hypertrophy, indicated by increased protein/DNA ratio, and oxidative stress measured as loss of cellular thiols. Rapid pacing additionally provoked structural alterations of mitochondria. All these changes are known to occur in vivo during atrial fibrillation. The structural alterations of mitochondria were accompanied by limitation of ATP production as evidenced by decreased endogenous respiration in combination with decreased ATP levels in intact cells. Inhibition of calcium inward current with verapamil protected against hypertrophic response and oxidative stress. Verapamil ameliorated morphological changes and dysfunction of mitochondria. In conclusion, rapid pacing-dependent changes in calcium inward current via L-type channels mediate both oxidative stress and mitochondrial dysfunction. The in vitro pacing model presented here reflects changes occurring during tachycardia and, thus, allows functional analyses of the signaling pathways involved. (c) 2006 Elsevier B.V. All rights reserved.

【 授权许可】

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