EFFECTS OF DIETARY MANGANESE ON ARTERIAL GLYCOSAMINOGLYCAN METABOLISMIN SPRAGUE-DAWLEY RATS

The objectives of this study were to determine whether dietary mangane se deficiency alters total glycosaminoglycan (GAG) concentration and c omposition and glycosyltransferase activity in rat aortas. Sprague-Daw ley rats were fed either a manganese-deficient or a manganese-sufficie nt diet. Arterial GAGs were isolated and quantified by measuring uroni c acid content. The individual GAGs were separated and quantified with cellulose acetate electrophoresis. The activity of the enzyme galacto syltransferase I was measured using a 100,000 g particulate fraction a nd 4-methylumbelliferylxyloside (Xyl-MU) as an acceptor. There was a s ignificant decrease (p less than or equal to 0.05) in uronic acid cont ent in the manganese-deficient (1.18 +/- 0.08 mg/g) rat aortas as comp ared with the manganese-sufficient (1.59 +/- 0.10 mg/g) ones. Chondroi tin sulfate and heparan sulfate concentrations were decreased by 38% ( p less than or equal to 0.01) and 36% (p less than or equal to 0.05), respectively, in the manganese-deficient rat aortas. The incorporation of UDP-galactose to accepters by the manganese-deficient rat aorta pr eparations was increased by 28% as compared to the manganese-sufficien t preparations. These results indicate that manganese is involved in a rterial GAG metabolism by affecting the enzyme galactosyltransferase a nd that changes in GAG concentration and composition with manganese de ficiency may ultimately affect arterial wall integrity and subsequentl y cardiovascular health. This is the first work to demonstrate that ma nganese nutrition is important in arterial GAG metabolism.