Effects of elevated glucose concentrations on the metabolism of the aortic wall.
The effects of elevated glucose concentrations on the metabolism of the aortic wall were examined in a preparation of tubular segments of rabbit descending thoracic aorta comprised of intima and media only. Increased medium glucose concentrations (20-50 mm) resulted in increased aortic sorbitol and fructose concentrations and an increased rate of fructose release into the medium. This increased flux through the polyol pathway can be explained as a consequence both of an increased free intracellular glucose concentration and of the kinetic characteristics of the alditol: NADP oxidoreductase and the l-iditol: NAD oxidoreductase isolated and partially purified from rabbit thoracic aorta. Incubation with elevated glucose concentrations for 2 or more hr was also associated with a significant increase in the water content of the tissue without a significant increase in the inulin space. The oxygen uptake of the tissues incubated with elevated glucose concentrations was significantly reduced; this appears to result from a limitation imposed by oxygen diffusion at physiological oxygen tensions. A compensatory increase in glycolysis and an increase in the aortic lactate/pyruvate concentration ratio were also observed. The oxygen uptake and lactate production of tissue incubated with 50 mm glucose could be preserved at rates observed in tissue incubated with a physiological glucose concentration by the addition of 40 mm mannitol to the medium. Aortic intima and media from alloxan-diabetic rabbits also exhibit an increased water content and a decreased rate of oxygen uptake. These observations suggest that elevated ambient glucose concentrations result in significant alterations in the metabolism of aortic intima and media.
D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic / Q000201:enzymology / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D006019:Glycolysis; D006943:Hyperglycemia / Q000378:metabolism; D066298:In Vitro Techniques; D007444:Inulin / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D008353:Mannitol / Q000494:pharmacology; D010101:Oxygen Consumption; D011773:Pyruvates / Q000378:metabolism; D011817:Rabbits; D013012:Sorbitol / Q000378:metabolism; D014867:Water / Q000378:metabolism
D001786:Blood Glucose; D007773:Lactates; D011773:Pyruvates; D014867:Water; D005632:Fructose; D008353:Mannitol; D013012:Sorbitol; D007444:Inulin; D000429:Alcohol Oxidoreductases; D005947:Glucose