Mitochondria-targeted Cardioprotection in Aldosteronism

作者：Shahbaz Atta U; Kamalov German; Zhao Wenyuan; Zhao Tieqiang; Johnson Patti L; Sun Yao; Bhattacharya Syamal K; Ahokas Robert A; Gerling Ivan C; Weber Karl T^*

来源：Journal of Cardiovascular Pharmacology, 2011, 57(1): 37-43.

DOI：10.1097/FJC.0b013e3181fe1250

• aldosteronism
• mitochondria
• intracellular calcium overloading
• oxidative stress mitochondrial permeability transition pore

Chronic aldosterone/salt treatment (ALDOST) is accompanied by an adverse structural remodeling of myocardium that includes multiple foci of microscopic scarring representing morphologic footprints of cardiomyocyte necrosis. Our previous studies suggested that signal-transducer-effector pathway leading to necrotic cell death during ALDOST includes intramitochondrial Ca(2+) overloading, together with an induction of oxidative stress and opening of the mitochondrial permeability transition pore (mPTP). To further validate this concept, we hypothesized that mitochondria-targeted interventions will prove to be cardioprotective. Accordingly, 8-week-old male Sprague-Dawley rats receiving 4 weeks ALDOST were cotreated with either quercetin, a flavonoid with mitochondrial antioxidant properties, or cyclosporine A (CsA), an mPTP inhibitor, and compared with ALDOST alone or untreated, age/sex-matched controls. We monitored mitochondrial free Ca(2+) and biomarkers of oxidative stress, including 8-isoprostane and H(2)O(2) production; mPTP opening; total Ca(2+) in cardiac tissue; and collagen volume fraction to quantify replacement fibrosis, a biomarker of cardiomyocyte necrosis, and employed terminal deoxynucleotidyl transferase dUTP nick end labeling assay to address apoptosis in coronal sections of ventricular myocardium. Compared with controls, at 4 weeks ALDOST we found a marked increase in mitochondrial H(2)O(2) production and 8-isoprostane levels, an increased propensity for mPTP opening, and greater concentrations of mitochondrial free [Ca(2+)](m) and total tissue Ca(2+), coupled with a 5-fold rise in collagen volume fraction without any terminal deoxynucleotidyl transferase dUTP nick end labeling-based evidence of cardiomyocyte apoptosis. Each of these pathophysiologic responses to ALDOST was prevented by quercetin or cyclosporine A cotreatment. Thus, mitochondria play a central role in initiating the cellular-subcellular mechanisms that lead to necrotic cell death and myocardial scarring. This destructive cycle can be interrupted and myocardium salvaged with its structure preserved by mitochondria-targeted cardioprotective strategies.

• 出版日期2011-1