Impaired oxidative metabolism and calcium mishandling underlie cardiac dysfunction in a rat model of post-acute isoproterenol-induced cardiomyopathy

B. Cicero Willis, Ayleen Salazar-Cantú, Christian Silva-Platas, Evaristo Fernández-Sada, César A. Villegas, Eduardo Rios-Argaiz, Pilar González-Serrano, Luis A. Sánchez, Carlos E. Guerrero-Beltrán, Noemí García, Guillermo Torre-Amione, Gerardo J. García-Rivas, Julio Altamirano

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Stress-induced cardiomyopathy, triggered by acute catecholamine discharge, is a syndrome characterized by transient, apical ballooning linked to acute heart failure and ventricular arrhythmias. Rats receiving an acute isoproterenol (ISO) overdose (OV) suffer cardiac apex ischemia-reperfusion damage and arrhythmia, and then undergo cardiac remodeling and dysfunction. Nevertheless, the subcellular mechanisms underlying cardiac dysfunction after acute damage subsides are not thoroughly understood. To address this question, Wistar rats received a single ISO injection (67 mg/kg). We found in vivo moderate systolic and diastolic dysfunction at 2 wk post-ISO-OV; however, systolic dysfunction recovered after 4 wk, while diastolic dysfunction worsened. At 2 wk post-ISO-OV, cardiac function was assessed ex vivo, while mitochondrial oxidative metabolism and stress were assessed in vitro, and Ca2+ handling in ventricular myocytes. These were complemented with sarco(endo)- plasmic reticulum Ca2+-ATPase (SERCA), phospholamban (PLB), and RyR2 expression studies. Ex vivo, basal mechanical performance index (MPI) and oxygen consumption rate (MVO2) were unchanged. Nevertheless, upon increase of metabolic demand, by β-adrenergic stimulation (1–100 nM ISO), the MPI versus MVO2 relation decreased and shifted to the right, suggesting MPI and mitochondrial energy production uncoupling. Mitochondria showed decreased oxidative metabolism, membrane fragility, and enhanced oxidative stress. Myocytes presented systolic and diastolic Ca2+ mishandling, and blunted response to ISO (100 nM), and all these without apparent changes in SERCA, PLB, or RyR2 expression. We suggest that post-ISO-OV mitochondrial dysfunction may underlie decreased cardiac contractility, mainly by depletion of ATP needed for myofilaments and Ca2+ transport by SERCA, while exacerbated oxidative stress may enhance diastolic RyR2 activity.

Original languageEnglish (US)
Pages (from-to)H467-H477
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume308
Issue number5
DOIs
StatePublished - 2015

Keywords

  • Calcium signaling
  • Cardiac dysfunction
  • Isoproterenol
  • Mitochondrial dysfunction
  • Takotsubo cardiomyopathy

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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