Abstract: Cardinal pathological features of hypertensive heart disease (HHD) include not only hypertrophied cardiomyocytes and foci of scattered microscopic scarring, a footprint of prior necrosis, but also small myocytes ensnared by fibrillar collagen where disuse atrophy with protein degradation would be predicted. Whether atrophic signaling is concordant with the appearance of HHD and involves oxidative and endoplasmic reticulum (ER) stress remains unexplored. Herein, we examine these possibilities focusing on the left ventricle and cardiomyocytes harvested from hypertensive rats receiving 4 weeks aldosterone/salt treatment (ALDOST) alone or together with ZnSO4, a nonvasoactive antioxidant, with the potential to attenuate atrophy and optimize hypertrophy. Compared with untreated age-/sex-/strain-matched controls, ALDOST was accompanied by (1) left ventricle hypertrophy with preserved systolic function; (2) concordant cardiomyocyte atrophy (<1000 μm2) found at sites bordering on fibrosis where they were reexpressing β-myosin heavy chain; and (3) upregulation of ubiquitin ligases, muscle RING-finger protein-1 and atrogin-1, and elevated 8-isoprostane and unfolded protein ER response with messenger RNA upregulation of stress markers. ZnSO4 cotreatment reduced lipid peroxidation, fibrosis, and the number of atrophic myocytes, together with a further increase in cell area and width of atrophied and hypertrophied myocytes, and improved systolic function but did not attenuate elevated blood pressure. We conclude that atrophic signaling, concordant with hypertrophy, occurs in the presence of a reparative fibrosis and induction of oxidative and ER stress at sites of scarring where myocytes are atrophied. ZnSO4 cotreatment in HHD with ALDOST attenuates the number of atrophic myocytes, optimizes size of atrophied and hypertrophied myocytes, and improves systolic function.
*Department of Medicine, Division of Cardiovascular Diseases;
Departments of †Obstetrics and Gynecology; and
‡Microbiology, Immunology and Biochemistry; and
§Department of Medicine, Division of Endocrinology, University of Tennessee Health Science Center, Memphis, TN.
G. Kamalov is now with the Division of Cardiovascular Medicine, Ohio State University, Columbus, OH.
Reprints: Karl T. Weber, MD, Division of Cardiovascular Diseases, University of Tennessee Health Science Center, 956 Court Avenue, Suite A312, Memphis, TN 38163 (e-mail: firstname.lastname@example.org).
Supported, in part, by National Institutes of Health (NIH) grants R01-HL73043 and R01 HL90867 (K.T.W.). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.
The authors report no conflicts of interest.
Received May 16, 2013
Accepted August 19, 2013