Shinichi Hirotani

The antioxidant N-2-mercaptopropionyl glycine attenuates left ventricular hypertrophy in in vivo murine pressure-overload model.

OBJECTIVESnIn order to identify the role of reactive oxygen species (ROS) in cardiac hypertrophy, we examined the effect of N-2-mercaptopropionyl glycine (MPG) on cardiac hypertrophy.nnnBACKGROUNDnRecent in vitro studies have suggested that ROS play an important role as a second messenger in cardiac hypertrophy. It was therefore thought to be of particular value to examine the relevance of studies using in vitro models for cardiac hypertrophy in an in vivo setting.nnnMETHODSnThe transverse thoracic aorta in mice was constricted, and MPG (100 mg/kg) was infused intraperitoneally twice daily. The animals were assessed seven days after the operation for hemodynamic functions, oxidative stress and antioxidative enzyme activities.nnnRESULTSnBanding of the transverse aorta in mice resulted in an increase in the ratio of heart weight to tibia length and the appearance of an endogenous atrial natriuretic factor messenger ribonucleic acid (mRNA) seven days postoperatively. Administration of MPG significantly attenuated the hypertrophic responses induced by pressure overload. Cardiac hypertrophy was accompanied by increases in heme oxygenase-1 mRNA expression and lipid peroxidation, which was eliminated by the treatment with MPG. Pressure overload led to increases in antioxidant enzyme activities, such as superoxide dismutase and glutathione peroxidase, but not catalase, activity.nnnCONCLUSIONSnOur results indicated that oxidative stress was increased in our model and that it plays an important role in the development of cardiac hypertrophy.

Disruption of a single copy of the p38α MAP kinase gene leads to cardioprotection against ischemia–reperfusion

The p38 mitogen-activated protein kinase (p38) is activated in the heart during ischemia-reperfusion. However, it is not clear whether the activation of p38 is the protective response or the kinase mediates the cellular damage by ischemia-reperfusion. We examined the role of p38alpha in ischemia-reperfusion injury by studying p38alpha(+/-) mice. The p38alpha protein level in the p38alpha(+/-) heart was 50+/-8.7% compared with that in the p38alpha(+/+) heart. Upon reperfusion following ischemia for 25min, p38alpha activity was transiently increased. The maximum level of p38 activity in p38alpha(+/-) was 60+/-10.5% compared with that in p38alpha(+/+). In the p38alpha(+/+) heart, 25min ischemia and 2h reperfusion resulted in necrotic injury (37.1+/-2.7% of the area at risk), whereas infarct size was drastically reduced to 7.2+/-0.7% in the p38alpha(+/-) heart. These suggested that p38alpha plays a pivotal role in the signal transduction pathway mediating myocardial cell death caused by ischemia-reperfusion.

Single-strand conformation polymorphism analysis on the δ-sarcoglycan gene in Japanese patients with hypertrophic cardiomyopathy ☆

To elucidate the etiology of hypertrophic cardiomyopathy (HC) in humans, we analyzed the delta-sarcoglycan gene (SG), which is reported to be the causal gene for HC in the Syrian hamster BIO14.6. We performed polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses on the delta-SG in 102 patients with HC. SSCP was detected in exon 2 of the gene, but not in the other exons. The direct sequencing analysis of exon 2 revealed a C-->T substitution at nucleotide residue 84 (TAC-->TAT) with no amino acid alteration (Tyr-->Tyr). There were no significant differences in allele frequencies of C/T between the patients with HC and the control group. Patients with HC were classified into 4 subgroups: obstructive HC, nonobstructive HC, apical HC, and familial HC. The allele frequency of C/T polymorphism in each of these groups was compared with that of the control group. The obstructive HC group showed a significantly greater frequency of the allele T than in the control group (31.6% vs 15.1%, RR = 2.6, p = 0.023). No other significant differences were observed. Thus, amino acid alteration in delta-SG may not be a common cause of HC in Japanese patients.