title: Endothelin B-receptors and sympathetic activation: impact on ventricular arrhythmogenesis during acute myocardial infarction.
abstract: OBJECTIVE
  We investigated the role of endothelin-B receptors on sympathetic activation originating from the adrenal gland or from the myocardium and its impact on arrhythmogenesis during acute myocardial infarction.
  
  
  METHODS
  We studied two groups of rats (n=120, 284±2 g), namely wild-type and ETB-deficient. Myocardial infarction was induced by permanent ligation of the left coronary artery and ventricular tachyarrhythmias were evaluated from continuous electrocardiographic recordings. Sympathetic activation, measured by indices of heart rate variability, was evaluated after adrenalectomy or catecholamine depletion induced by reserpine. Acute left ventricular failure was assessed by total animal activity.
  
  
  RESULTS
  Adrenalectomy decreased the total duration of tachyarrhythmias in ETB-deficient rats, but their incidence remained higher, compared to wild-type rats. After reserpine, heart rate variability indices and tachyarrhythmias were similar in the two groups during the initial, ischaemic phase. During evolving infarction, tachyarrhythmia duration was longer in ETB-deficient rats, despite lower sympathetic activation. Heart rate was lower in ETB-deficient rats throughout the 24-hour observation period, whereas activity was comparable in the two groups.
  
  
  CONCLUSIONS
  Endothelin-B receptors modulate sympathetic activation during acute myocardial infarction not only in the ventricular myocardium, but also in the adrenal gland. Sympathetic activation markedly increases early-phase ventricular tachyarrhythmias, but other mechanisms involving the endothelin system underlie delayed arrhythmogenesis.
authors: Department of Cardiology, University of Ioannina, Ioannina, Greece; Cardiovascular Research Institute, Ioannina and Athens, Greece. Electronic address: thkolet@cc.uoi.gr.
authors: Theofilos M
authors: TM
authors: Kolettis
authors: Department of Cardiology, University of Ioannina, Ioannina, Greece.
authors: Dimitrios L
authors: DL
authors: Oikonomidis
authors: Department of Cardiology, University of Ioannina, Ioannina, Greece; Cardiovascular Research Institute, Ioannina and Athens, Greece; Experimental Research Center ELPEN, Pikermi, Athens, Greece.
authors: Maria-Eleni E
authors: ME
authors: Baibaki
authors: Department of Materials Science and Engineering, University of Ioannina, Greece.
authors: Eleonora
authors: E
authors: Barka
authors: Department of Cardiology, University of Ioannina, Ioannina, Greece; Cardiovascular Research Institute, Ioannina and Athens, Greece.
authors: Marianthi
authors: M
authors: Kontonika
authors: Engineering Informatics and Telecommunications, University of Western Macedonia, Kozani, Greece.
authors: Dimitrios G
authors: DG
authors: Tsalikakis
authors: Cardiovascular Research Institute, Ioannina and Athens, Greece; Experimental Research Center ELPEN, Pikermi, Athens, Greece.
authors: Apostolos
authors: A
authors: Papalois
authors: Cardiovascular Research Institute, Ioannina and Athens, Greece; First Department of Cardiology, Red Cross Hospital, Athens, Greece.
authors: Zenon S
authors: ZS
authors: Kyriakides
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000311:Adrenal Glands / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D000315:Adrenalectomy; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology*; D006352:Heart Ventricles / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology*; D051381:Rats; D044023:Receptor, Endothelin B / Q000378:metabolism*; D012110:Reserpine / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D044023:Receptor, Endothelin B; D012110:Reserpine
keywords: Adrenal gland; Endothelin-B receptor; Myocardial infarction; Ventricular tachyarrhythmias