Bioenergetic remodeling of heart during treatment of spontaneously hypertensive rats with enalapril

• Published in: American journal of physiology. Heart and circulatory physiology 2002-08, Vol.52 (2), p.H540-H548
• Main Authors: LEARY, S. C, MICHAUD, D, LYONS, C. N, HALE, T. M, BUSHFIELD, T. L, ADAMS, M. A, MOYES, C. D
• Format: Article
• Language: English
• Subjects: Antihypertensive agents; Biological and medical sciences; Blood pressure; Cardiology; Cardiovascular system; Drug therapy; Heart; Hypertension; Medical sciences; Pharmacology. Drug treatments; Rodents
• ISSN: 0363-6135; 1522-1539

We used spontaneously hypertensive rats to study remodeling of cardiac bioenergetics associated with changes in blood pressure. Blood pressure was manipulated with aggressive antihypertensive treatment combining low dietary salt and the angiotensin-converting enzyme inhibitor enalapril. Successive cycles of 2 weeks on, 2 weeks off treatment led to rapid, reversible changes in left ventricular (LV) mass (30% change in less than 10 days). Despite changes in LV mass, specific activities of bioenergetic (cytochrome-c oxidase, citrate synthase, lactate dehydrogenase) and reactive oxygen species (ROS) (total cellular superoxide dismutase) enzymes were actively maintained within relatively narrow ranges regardless of treatment duration, organismal age, or transmural region. Although enalapril led to parallel declines in mitochondrial enzyme content and ventricular mass, total ventricular mtDNA content was unaffected. Altered enzymatic content occurred without significant changes in relevant mRNA and protein levels. Transcript levels of gene products involved in mtDNA maintenance (Tfam), mitochondrial protein degradation (LON protease), fusion (fuzzy onion homolog), and fission (dynamin-like protein, synaptojanin-2) were also unchanged. In contrast, enalapril-mediated ventricular and mitochondrial remodeling was accompanied by a twofold increase in specific activity of catalase, an indicator of oxidative stress, suggesting that rapid cardiac adaptation is accompanied by tight regulation of mitochondrial enzyme activities and increased ROS production.