THE INFLUENCE OF DIETARY CARBOHYDRATES ON PLASMA LIPOPROTEINS AND AORTIC GLYCOSAMINOGLYCANS IN THE RABBIT.

Format:

Book

Thesis/Dissertation

Author/Creator:

DE HOFF, JANET LINDSAY.

Contributor:

University of Pennsylvania.

Subjects (All):

Pathology.

0571.

Local Subjects:

0571.

Physical Description:

284 pages

Contained In:

Dissertation Abstracts International 41-10B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

The effect of dietary carbohydrates on the atherogenicity of a semi-purified diet in rabbits was examined. Previous studies from this laboratory have indicated that a semi-purified diet consisting by weight of 40% carbohydrate, 25% casein, 14% hydrogenated coconut oil, 15% cellulose, 5% salt mix and 1% vitamin mix resulted in atherosclerosis in rabbits. The type of carbohydrate influenced the atherogenicity of the diet. Sucrose or fructose in contrast to glucose or lactose resulted in more rapid development of hypertriglyceridemia and of hypercholesterolemia and more severe atherosclerosis. The observed hyperlipidemia indicated that plasma lipoprotein alterations had occurred. The differential atherogenicity of dietary carbohydrate may be explained by secondary effects of lipoproteins on the arterial wall. Alternatively, the carbohydrate component could affect the arterial wall directly by altering the metabolism of mural components.

To study the role of dietary carbohydrate in aortic atherogenesis, rabbits were fed semi-purified diets containing different carbohydrates for 10 and 20 week periods. Tissue analyses included liver lipids, aortic lipids and aortic glycosaminoglycans. Glycosaminoglycans were quantitated after isolation by analysis of hexuronic acid, hexosamine and galactosamine. Individual aortic glycosaminoglycans including hyaluronic acid, heparan sulfate, dermatan sulfate, and chondroitin sulfates were analyzed by cellulose acetate electrophoresis in 0.1 M cupric acetate buffer and Alcian blue staining. Electrophoresis was standardized using authentic rabbit aortic glycosaminoglycan standards prepared by DEAE-Sephacel ion exchange column chromatography of pooled rabbit aortic glycosaminoglycans. Plasma analyses included plasma lipoproteins, lipids and glucose and these values were compared to normal ranges for rabbits which were determined for 50-100 rabbits fed laboratory chow ad lib. Rabbit plasma lipoproteins were analyzed for lipid content after separation by ultracentrifugation flotation. The semi-purified diet regardless of the type of carbohydrate led to elevations of plasma cholesterol after 10 weeks of feeding probably as a result of the saturated fat component of the diet. After 10 weeks of sucrose feeding plasma cholesterol levels were elevated to 6-8 fold while lactose feeding elevated plasma cholesterol levels 2-4 fold. Increases in plasma cholesterol were a result of increases in apolipoprotein B containing lipoproteins (very low density lipoprotein, intermediate density lipoprotein, and low density lipoprotein) whereas high density lipoprotein cholesterol remained constant. In Dutch-Belted rabbits glycosaminoglycans were significantly increased in aortas of hypercholesterolemic sucrose-fed rabbits compared to relatively normocholesterolemic rabbits (plasma cholesterol levels less than 120 mg per dL). At 10 weeks glycosaminoglycan increases were due to increased hyaluronic acid, dermatan sulfate and chondroitin sulfate whereas only hyaluronic acid and chondroitin sulfate remained increased after 20 weeks. Glycosaminoglycan hexuronic acid, hexosamine, galactosamine and total glycosaminoglycans (by electrophoresis) were strongly correlated to aortic total cholesterol concentration (r greater than 0.78) which in turn was correlated with hypercholesterolemia. As increased glycosaminoglycans have been implicated as the earliest change in atherogenesis the results of this study suggest that the accumulation of glycosaminoglycans and cholesterol during hypercholesterolemia occur concurrently.

Notes:

Source: Dissertation Abstracts International, Volume: 41-10, Section: B, page: 3745.

Thesis (Ph.D.)--University of Pennsylvania, 1980.

Local Notes:

School code: 0175.

Access Restriction:

Restricted for use by site license.