This project defines how alcohol, AIDS, and nucleoside analog reverse transcriptase inhibitor (NRTI) treatment contribute to mitochondrial energy depletion, oxidative stress (imbalance between production of free radicals and antioxidant defenses), and cardiomyopathy (contractile failure; CM). CM is a frequent and serious consequence of alcohol use. Its putative mechanisms include oxidative stress and altered mitochondrial energetics. The NRTI zidovudine (AZT) is a cornerstone of AIDS therapy. AZT causes CM in vivo through mechanisms of energy depletion. AZT triphosphate inhibits cardiac mitochondrial DNA pol-gamma and alters mtDNA replication. Recently, AZT caused oxidation of mtDNA and altered cardiac mitochondrial structure, suggesting the mechanistic importance of oxidative stress. Since NRTI treatment for AIDS and alcohol consumption may coexist in the same patient, (particularly as AIDS survival increases), it is reasonable to hypothesize additive or synergistic energy depletion or oxidative stress from each. The working hypothesis states: CM results from AIDS, AZT, and from alcohol use. When AIDS, AZT (or related NRTI therapy), and alcohol consumption occur together, additive or synergistic damage to cardiac mitochondria results. Mechanisms for mitochondrial damage include energy depletion and oxidative stress.
The AIMS are:
AIM 1 : to define mitochondrial biogenesis and mitochondrial energetics in energy depletion and oxidative stress in AIDS, NRTI therapy and alcohol consumption. mtDNA and mtRNA abundance, and mitochondrial polypeptide synthesis reflect mitochondrial biogenesis and function. Oxidized guanosine (8-OhdG) in total- and mtDNA, and cardiac glutathione (GSH/GSSG) content are markers of mitochondrial oxidative stress. Mitochondrial aconitase inactivation reflects oxidative damage to mitochondrial proteins.
AIM 2 : to define cardiac performance with altered mitochondrial energetics and oxidative stress from AIDS, NRTI therapy and alcohol consumption. Serial echocardiograms determine LV mass, wall thickness, and chamber dimensions and shortening. Isolated hearts are used to analyze cardiac contractility and relaxation in the absence of ventriculo-vascular coupling and circulating neurohormones.
AIM 3 : to define cardiac structural features that result from altered mitochondrial energetics and oxidative stress. Myofibrillar, nuclear and mitochondrial volumes are analyzed quantitatively (by transmission electron microscopy [TEM]). Volume fractions of extracellular matrix and of myocytes are determined morphometrically (light and TEM).
