The fetal syndrome (FAS) is associated with several cardiac abnormalities. The striking effect of alcohol on embryonic cardiac muscle development is reflected in the fact that 30-45% of infants born with FAS exhibit heart defects. Two major disturbance reported in animal models of FAS are a depression in cardiac muscle oxidative metabolism and a disruption of the mitochondrial inner membrane structure. The mechanism by which alcohol induces these defects is unknown. This application proposes to examine the role of mitochondrial gene transcription and intracellular calcium in mediating the response of embryonic cardiac muscle to chronic ethanol exposure. Cytochrome c oxidase is a key enzyme in oxidative metabolism which is located on the ethanol-disrupted mitochondrial inner membrane. The activity of this enzyme, as well as a mitochondrial matrix enzyme citrate synthase, will be determined in normal and ethanol-treated embryonic heart. The effect of ethanol on hypothermia-induced embryonic cardiac muscle hypertrophy and upregulation of oxidative metabolism will be evaluated. In addition, the effect of ethanol on expression of contractile protein isoforms will be analyzed using anti-myosin heavy chain antibodies. A cDNA clone coding for the mitochondrially-encoded cytochrome c oxidase subunit III (COIII) has been isolated. This clone will be characterized and used in RNA and DNA blotting techniques. COIII mRNA expression will be evaluated in normal and ethanol-treated chick embryos to determine if mitochondrial transcription is altered in cardiomyopathies of FAS. The time course for changes in CO activity and COIII and mRNA expression will be compared to determine if transcriptional changes are responsible for changes in CO activity. Changes in mitochondrial DNA concentration will also be evaluated to determine if ethanol alters the mitochondrial DNA copy number. Cardiac myocyte cultures will be used to evaluated the direct effects of ethanol on CO activity and COIII mRNA expression in cardiac cells in the absence of systemic and neurogenic effects. Changes in intracellular calcium have been implicated in ethanol effects on neural and muscle tissue. Therefore, calcium uptake and the number of dihydropyridine- sensitive binding sites will be determined in normal and ethanol-treated cultures. The role of calcium in mediating ethanol-induces changes in CO activity and COIII mRNA will be evaluated in cardiocyte cultures by calcium-channel blockade. The experiments proposed in this application will provide information regarding the mechanisms responsible for ethanol-induced cardiac abnormalities in FAS which can be used to devise treatments which will reverse or present the occurrence of alcohol-related cardiomyopathies.
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| McCurdy 3rd, D T; Kennedy, J M (1996) Skeletal muscle mitochondria from AZT-treated rats have a diminished response to chronic electrical stimulation. J Appl Physiol 81:326-34 |
| Kennedy, J M; Kelley, S W; Meehan, J M (1993) Ventricular mitochondrial gene expression during development and following embryonic ethanol exposure. J Mol Cell Cardiol 25:117-31 |
| Kennedy, J M; Lobacz, S R; Kelley, S W (1991) Mitochondrial DNA replication and transcription are dissociated during embryonic cardiac hypertrophy. Am J Physiol 261:C1091-8 |
