Influence of exogenous substrates on adenosinetriphosphate (ATP) concentration in normal and diabetic rat aorta in vitro

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Abstract
In diabetic rat aorta glucose metabolism is impaired and changes in the activities of several enzymes are found. The aim of this study was to investigate whether the metabolic alterations in diabetic vascular tissue influence energy production. Aortas of normal and diabetic male Sprague-Dawley rats were incubated in vitro for up to 120 min with various substrates added to the incubation medium. Diabetes was induced by streptozotocin and the rats were used after a diabetes duration of 2 wk. When normal and diabetic aorta were incubated in the presence of 5.6 mmol/l glucose no significant difference in ATP-concentration was found after 60 min while after 120 min the ATP-concentration was lower in diabetic aorta. Addition to the incubation medium of a substrate mixture containing amino acids in the same concentrations as in rat plasma, 3 mmol/l DL-.beta.-hydroxybutyrate and 1.5 mmol/l palmitate increased the ATP-concentration, measured after 120 min, in diabetic aorta but not in normal aorta. No significant difference in ATP-concentration was found between normal and diabetic aorta incubated in a medium containing all substrates. When diabetic aorta was incubated with each substrate separately .beta.-hydroxybutyrate but not glucose, palmitate or amino acids, increased the ATP-concentration to about the same level as the complete substrate mixture. The ability to utilize glucose for ATP production is impaired in diabetic vascular tissue and that other substrates such as ketone bodies are of importance for energy production in diabetic vessels.