Why the study?
Does isoproterenol or digoxin alter cardiac performance, mitochondrial activity, and glycolysis in isolated hearts from chronic alcohol-treated and cardiomyopathic hamsters?
Does isoproterenol or digoxin alter cardiac performance, mitochondrial activity, and glycolysis in isolated hearts from chronic alcohol-treated and cardiomyopathic hamsters?
In a hamster model, isoproterenol reverses the depressive effects of chronic alcohol and cardiomyopathy on cardiac performance and glycolysis, whereas digoxin exacerbates these adverse effects.
Does not support digoxin in alcohol cardiomyopathy; hypothesis-generating for isoproterenol effects in preclinical models.
The purpose of this study was to confirm that an agent, which increases diastolic [Ca2+]i, namely digoxin, depresses cardiac performance, mitochondrial activity, and glycolysis in chronic alcohol-treated and myopathic hearts, and that an agent, which lowers diastolic [Ca2+]i, namely isoproterenol, activates cardiac performance, mitochondrial activity, and glycolysis in these animals. Energy levels, glycolysis, mitochondrial activity, hemodynamics, and cAMP were studied in isolated hearts from three groups of animals, i.e., 9-month control hamsters, hamsters given 50% alcohol until 9 months of age, and 6-month-old cardiomyopathic hamsters in heart failure. Isolated hearts were perfused with either a control medium, a medium containing isoproterenol, digoxin, or digoxin + isoproterenol. Measurement of phosphomonoester sugars, and glucose-6-phosphate, were used to assess glycolytic activity. Oxygen consumption was used to analyze mitochondrial activity. All hearts perfused with either isoproterenol or isoproterenol + digoxin showed an increase in developed pressure, rate-pressure-product, and a decrease in end-diastolic pressure. Isoproterenol activated mitochondrial activity and glycolysis in hearts from myopathic and chronic alcohol hamsters. Based on 31P-NMR studies, isoproterenol or isoproterenol + digoxin improved the over-all energy state of hearts from cardiomyopathic hamsters, but not hearts from control and chronic alcohol hamsters. Digoxin alone augmented the rate-pressure-product and oxygen consumption in control hearts but not hearts from myopathic and chronic alcohol hamsters. Digoxin caused an increase in end-diastolic pressure in myopathic and chronic alcohol hearts but not control hearts. Digoxin depressed glycolysis and worsened the energy state in hearts from cardiomyopathic and chronic alcohol hamsters, but not hearts from control hamsters. In conclusion digoxin, but not isoproterenol nor isoproterenol + digoxin, depressed cardiac performance and glycolysis as well as high energy phosphates in cardiomyopathic and chronic alcohol hearts. Isoproterenol added to digoxin negated the adverse effects of digoxin in cardiomyopathic and chronic alcohol hearts.
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Auffermann et al. (1992) studied this question.
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