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Medicina is published by MDPI from Volume 54 Issue 1 (2018). Articles in this Issue were published by another publisher in Open Access under a CC-BY (or CC-BY-NC-ND) licence. Articles are hosted by MDPI on mdpi.com as a courtesy and upon agreement with Lithuanian Medical Association, Lithuanian University of Health Sciences, and Vilnius University.
Open AccessArticle

Effect of inhibitors of mitochondrial respiratory chain complexes on the electromechanical activity in human myocardium

Institute of Cardiology, Medical Academy, Lithuanian University of Health Sciences, Lithuania
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Author to whom correspondence should be addressed.
Medicina 2010, 46(10), 679; https://doi.org/10.3390/medicina46100096
Received: 23 September 2008 / Accepted: 6 October 2010 / Published: 11 October 2010
The aim of the study was to investigate the effect of inhibitors of mitochondrial respiratory chain complexes I, III, and IV on the electromechanical activity in human myocardium.
Material and methods
. The experiments were performed on the human myocardial strips obtained from patients with heart failure (NYHA class III or IV) using a conventional method of registration of myocardial electromechanical activity. Under the perfusion with physiological Tyrode solution (control), contraction force (P) was 0.94±0.12 mN (n=16), relaxation time (t50) was 173.38±5.03 ms (n=15), action potential durations measured at 50% (AP50) and 90% (AP90) repolarization were 248.96±13.38 ms and 398.59±17.93 ms, respectively (n=13).
Results. The inhibition of respiratory chain complex I by rotenone (3×10–5 M, the highest concentration applied) decreased contraction force of human myocardium to 48.99%±14.74% (n=3) (P<0.05); AP50, to 81.34%±15.81%; and AP90, to 87.28%±7.25% (n=3) (P>0.05) of control level, while relaxation time and resting tension remained almost unchanged. Antimycin A, an inhibitor of complex III, applied at the highest concentration (3×10–4 M) reduced P to 41.66%±8.8% (n=5) (P<0.001) and marginally increased t50 and decreased the durations of AP. Anoxia (3 mM Na2S2O4) that inhibits the activity of complex IV reduced the contraction force to 9.23%±3.56% (n=6) (P<0.001), AP50 and AP90 to 65.46%±9.95% and 71.07%±8.39% (n=5) (P<0.05) of control level, respectively; furthermore, the resting tension augmented (contracture developed).
Conclusions
. Our results show that the inhibition of respiratory chain complex IV had the strongest inhibitory effect on the electromechanical activity of failing human myocardium.
Keywords: human myocardium; rotenone; antimycin A; anoxia; electromechanical activity human myocardium; rotenone; antimycin A; anoxia; electromechanical activity
MDPI and ACS Style

Gendvilienė, V.; Martišienė, I.; Zablockaitė, D.; Jurevičius, J. Effect of inhibitors of mitochondrial respiratory chain complexes on the electromechanical activity in human myocardium. Medicina 2010, 46, 679.

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