Experimental Study of the Effects of EIPA, Losartan, and BQ-123 on Electrophysiological Changes Induced by Myocardial Stretch.
Rev Esp Cardiol (Engl Ed)
; 68(12): 1101-10, 2015 Dec.
Article
em En
| MEDLINE
| ID: mdl-25985899
ABSTRACT
INTRODUCTION AND OBJECTIVES:
Mechanical response to myocardial stretch has been explained by various mechanisms, which include Na(+)/H(+) exchanger activation by autocrine-paracrine system activity. Drug-induced changes were analyzed to investigate the role of these mechanisms in the electrophysiological responses to acute myocardial stretch.METHODS:
Multiple epicardial electrodes and mapping techniques were used to analyze changes in ventricular fibrillation induced by acute myocardial stretch in isolated perfused rabbit hearts. Four series were studied control (n = 9); during perfusion with the angiotensin receptor blocker losartan (1 µM, n = 8); during perfusion with the endothelin A receptor blocker BQ-123 (0.1 µM, n = 9), and during perfusion with the Na(+)/H(+) exchanger inhibitor EIPA (5-[N-ethyl-N-isopropyl]-amiloride) (1 µM, n = 9).RESULTS:
EIPA attenuated the increase in the dominant frequency of stretch-induced fibrillation (control=40.4%; losartan=36% [not significant]; BQ-123=46% [not significant]; and EIPA=22% [P<.001]). During stretch, the activation maps were less complex (P<.0001) and the spectral concentration of the arrhythmia was greater (greater regularity) in the EIPA series control=18 (3%); EIPA = 26 (9%) (P < .02); losartan=18 (5%) (not significant); and BQ-123=18 (4%) (not significant).CONCLUSIONS:
The Na(+)/H(+) exchanger inhibitor EIPA attenuated the electrophysiological effects responsible for the acceleration and increased complexity of ventricular fibrillation induced by acute myocardial stretch. The angiotensin II receptor antagonist losartan and the endothelin A receptor blocker BQ-123 did not modify these effects.Palavras-chave
Angiotensin inhibitors; Arrhythmia; Arritmia; Basic research; Biomechanical stress; Drugs; Electrofisiología; Electrophysiology; Endotelina; Endothelin; Estrés biomecánico; Fibrilación ventricular; Fármacos; Inhibidores de la angiotensina; Investigación básica; Mapeo; Mapping; Miocardio; Myocardium; Ventricular fibrillation
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Estresse Fisiológico
/
Coração
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Miocárdio
Limite:
Animals
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article