Oxidative Stress Causes Heart Failure with Impaired Mitochondrial Respiration

Hidetoshi Nojiri,Takahiko Shimizu,Masabumi Funakoshi,Osamu Yamaguchi,Heying Zhou,Satoru Kawakami,Yutaka Ohta,Manabu Sami,Toshiaki Tachibana,Hiroshi Ishikawa,Hisashi Kurosawa,Ronald C Kahn,Kinya Otsu,Takuji Shirasawa

doi:10.1074/jbc.m602118200

Abstract

Elderly people insidiously manifest the symptoms of heart failure, such as dyspnea and/or physical disabilities in an age-dependent manner. Although previous studies suggested that oxidative stress plays a pathological role in the development of heart failure, no direct evidence has been documented so far. In order to investigate the pathological significance of oxidative stress in the heart, we generated heart/muscle-specific manganese superoxide dismutase-deficient mice. The mutant mice developed progressive congestive heart failure with specific molecular defects in mitochondrial respiration. In this paper, we showed for the first time that the oxidative stress caused specific morphological changes of mitochondria, excess formation of superoxide (O(2)(*)(-)), reduction of ATP, and transcriptional alterations of genes associated with heart failure in respect to cardiac contractility. Accordingly, administration of a superoxide dismutase mimetic significantly ameliorated the symptoms. These results implied that O(2)(*)(-) generated in mitochondria played a pivotal role in the development and progression of heart failure. We here present a bona fide model for human cardiac failure with oxidative stress valuable for therapeutic interventions.

Highlights

Heart failure is a leading cause of mortality worldwide, affecting about 1–2% of the population in Japan, Europe, and the United States [1]
A 401-bp DNA fragment corresponding to the deletion allele was amplified by PCR from the heart and skeletal muscle of H/M-Sod2Ϫ/Ϫ mice, whereas no fragment was amplified in other tissues of H/M-Sod2Ϫ/Ϫ mice or in any tissues of control mice (Fig. 1B)
Western blot analyses further showed a specific loss of Manganese superoxide dismutase (Mn-SOD) expression in the heart and skeletal muscle of H/M-Sod2Ϫ/Ϫ mice (Fig. 1C), but no loss was observed in control mice

Summary

EXPERIMENTAL PROCEDURES

Animals and Genotyping—The generation of Mn-SOD flox mice was described previously [19]. Frozen sections were dried and incubated in 50 mM sodium phosphate (pH 7.4), 84 mM succinate acid, 0.2 mM phenazine methasulfate, 2 mg/ml nitro blue tetrazolium, and 4.5 mM EDTA for SDH (Complex II) activity or in 50 mM sodium phosphate (pH 7.4), 1.0 mg/ml 3,3Ј-diaminobenzidine, 24 units/ml catalase (Wako), 1 mg/ml cytochrome c (Wako), and 75 mg/ml sucrose for COX (Complex IV) activity. These reactions were performed in the dark at room temperature for 20 min. 0.74 Ϯ 0.02 3.55 Ϯ 0.08 0.76 Ϯ 0.05 1.27 Ϯ 0.06 2.02 Ϯ 0.09 1.35 Ϯ 0.12 533.87 Ϯ 16.52 43.17 Ϯ 1.39 67.65 Ϯ 1.60 22.63 Ϯ 0.50 117.33 Ϯ 7.07 135.67 Ϯ 5.57 0.52 Ϯ 0.03 0.60 Ϯ 0.03

RESULTS

4.22 Biosynthesis

DISCUSSION