AJP - Heart Calcium Transients and Cell-Sarcomere
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Am J Physiol Heart Circ Physiol (February 17, 2006). doi:10.1152/ajpheart.01307.2005
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Submitted on December 13, 2005
Accepted on February 17, 2006

ANGIOTENSIN II-INDUCED CARDIAC MOLECULAR AND CELLULAR EVENTS: ROLE OF ALDOSTERONE

Wenyuan Zhao1, Robert A Ahokas1, Karl T Weber1, and Yao Sun1*

1 Medicine, University of Tennessee, Memphis, TN, USA

* To whom correspondence should be addressed. E-mail: yasun{at}utmem.edu.

Chronic elevation of circulating angiotensin (Ang)II is associated to cardiac remodeling in patients with hypertension and heart failure. The underlying mechanisms, however, are not completely defined. Herein, we studied AngII-induced molecular and cellular events in the rat heart as well as their links to the redox state. We also addressed the potential contribution of aldosterone (ALDO) on AngII-induced cardiac remodeling. In AngII treated rats and compared to controls, we found: 1) the expression of proinflammatory/profibrogenic mediators was significantly increased in the perivascular space and at the sites of microscopic injury in both ventricles; 2) macrophages and myofibroblasts were primary repairing cells at these sites, together with increased fibrillar collagen volume; 3) apoptotic macrophages and myofibroblasts were evident at the same sites; 4) NADPH oxidase (gp91phox) was significantly enhanced at the these regions and primarily expressed by macrophages, while superoxide dismutase (SOD) and catalase levels remained unchanged; 5) plasma 8-isoprostane levels were significantly increased; and 6) blood pressure was significantly elevated. Losatan treatment completely prevented cardiac oxidative stress as well as molecular/cellular responses and normalized blood pressure. Spironolactone treatment partially suppressed the cardiac inflammatory/fibrogenic responses and redox state. Thus, chronic elevation of circulating AngII is accompanied by a proinflammatory/profibrogenic phenotype involving vascular and myocardial remodeling in both ventricles. Enhanced reactive oxygen species production at these sites and increased plasma 8-isoprostane indicate the involvement of oxidative stress in AngII-induced cardiac injury. ALDO contributes, in part, AngII-induced cardiac molecular and cellular responses.







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