Endothelin-B receptors and ventricular arrhythmogenesis in the rat model of acute myocardial infarction

Autor: Alexandros T. Tzallas, Aikaterini J. Megalou, Apostolos Papalois, Giannis G. Baltogiannis, Andreas Fotopoulos, Xanthi Xourgia, Zenon S. Kyriakides, Theofilos M. Kolettis, Dimitrios L. Oikonomidis, Maria G. Agelaki, Dimitrios G. Tsalikakis
Rok vydání: 2009
Předmět:
Zdroj: Basic research in cardiology. 105(2)
ISSN: 1435-1803
Popis: The arrhythmogenic effects of endothelin-1 (ET-1) are mediated via ETA-receptors, but the role of ETB-receptors is unclear. We examined the pathophysiologic role of ETB-receptors on ventricular tachyarrhythmias (VT/VF) during myocardial infarction (MI). MI was induced by coronary ligation in two animal groups, namely in wild-type (n = 63) and in ETB-receptor-deficient (n = 61) rats. Using a telemetry recorder, VT/VF episodes were evaluated during phase I (the 1st hour) and phase II (2-24 h) post-MI, with and without prior beta-blockade. Action potential duration at 90% repolarization (APD90) was measured from monophasic epicardial recordings and indices of sympathetic activation were assessed using fast-Fourier analysis of heart rate variability. Serum epinephrine and norepinephrine were measured with radioimmunoassay. MI size was similar in the two groups. There was a marked temporal variation in VT/VF duration; during phase I, it was higher (p = 0.0087) in ETB-deficient (1,519 +/- 421 s) than in wild-type (190 +/- 34 s) rats, but tended (p = 0.086) to be lower in ETB-deficient (4.2 +/- 2.0 s) than in wild-type (27.7 +/- 8.0 s) rats during phase II. Overall, the severity of VT/VF was greater in ETB-deficient rats, evidenced by higher (p = 0.0058) mortality (72.0% vs. 32.1%). There was a temporal variation in heart rate and in the ratio of low- to high-frequency spectra, being higher (
Databáze: OpenAIRE
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