Irrespective of its origins, asymptomatic (preclinical) ventricular dysfunction eventuates in: activation of the circulating renin-angiotensin-aldosterone system with symptomatic congestive heart failure (CHF) and a systemic illness with elevated plasma cytokines, anorexia & wasting (clinical); and progressive cardiac remodeling (pathologic). Cellular & molecular pathways involved at each stage remain to be elucidated. We use 4wk aldosterone (ALDO) treatment in rats and examine preclinical (wks 1-2), clinical (wk3), and clinicopathologic (wk4) stages. At vascular and nonvascular sites of injury that first appear in both atria & ventricles at wk4, evidence of NADPH oxidase expression and activity is found in invading immune ceils, together with activation of NFkB and expression of genes encoding for host defenses. Clinical and pathologic stages are prevented by co-treatment with spironolactone (Spi) or N-acetylcysteine (NAC). Herein we hypothesize this proinflammatory cardiac phenotype is a result of an immunostimulatory state found in peripheral blood mononuclear cells (PBMC) activated by oxi/nitrosative stress and induced by PBMC (Mg2+)i deficiency. Cardiac pathology, reported by others at wk3 of dietary Mg2+ deficiency, is likewise preceded by PBMC activation at wkl and is prevented by antioxidant or receptor antagonist (L-703,606) to substance P, a neurogenic mediator of inflammation. We examined the PBMC molecular phenotype (MP), including all expressed genes and proteins, obtained weekly from rats treated with ALDO/salt for 4wks. Changes in mRNA expression revealed an early (wk1) reduction in ATPase-dependent genes and a progressive development of oxi/nitrosative stress, and an upregulation of antioxidant defenses sustained over 4wks. B lymphocyte responses, including upregulation of antibody genes, appear from wkl on. Changes in protein expression identified early reduction in Mg 2+-dependent Ca 2+ pump and peroxiredoxin-I. Thus, the transcriptome and proteome of PBMC serve as early markers of stress and the systemic immunostimulatory state heralding the onset of illness and cardiac pathology. Specific Aims: 1) to monitor MP in PBMC activated in vivo and to determine the role of ALDO and Mg2+ by comparing responses to ALDO/salt plus Mg 2+ in a) standard (stan) or b) deficient (def) chows, c) with stan chow+Mg 2+ supplements, or d) Mg 2+ def chow alone (no ALDO); 2) to monitor MP of PBMC activated in vivo and determine genes & proteins involved in the appearance of illness and cardiac pathology by addressing the protective effects of Spi, NAC, or L-703,606; and 3) to determine the type(s) of PBMC necessary for the induction of the proinflammatory cardiac phenotype that appears in response to ALDO/salt/stan chow treatment. This study may identify preclinical markers that predict the development of CHF and cardiac remodeling, and may produce treatment strategies. [unreadable] [unreadable]