Role of Lipoprotein Lipase in Lipid Metabolism: The Effects of Exercise and Diet

Fatty acids derived from plasma triglycerides (TG) represent an important source of energy for skeletal and cardiac muscles and for storage in adipose tissue. In order to use plasma TG, fatty acids (FA) must be released from the glycerol backbone before uptake by tissues. Lipoprotein lipase (LPL) is a capillary bound enzyme which hydrolyzes plasma TG contained within chylomicrons and very low density lipoproteins. Lipoprotein lipase is essential for clearance of plasma TG and has been suggested to be the regulatory step in determining plasma TG concentrations. The studies presented in this thesis define changes in tissue LPL activities induced by a single exercise session, exercise training (moderate, treadmill running) and high dietary fat (72% kcals as vegetable shortening). In addition, relationships of tissue and plasma LPL activities to tissue uptake and plasma clearance of $\sp $C-labeled chylomicron TG (14C-CM-TG) were studied in rats fed the high fat diet. A single exercise session increased skeletal muscle and heart LPL activities with the highest activities and greatest responses in the heart and red muscle fiber types. Training moderated the effects of a single bout of exercise. The LPL activity of the red gastrocnemius muscle was elevated following both a single exercise bout and training. High dietary fat and 8 weeks of aerobic training elevated LPL activities of the red and white gastrocnemius muscles and adipose tissue with the effects being approximately additive. Finally, high dietary fat alone elevated fasting plasma TG levels and decreased LPL activities of heart, adipose tissue and post-heparin plasma, while there were virtually no changes in LPL activities of skeletal muscles. The decrease in LPL activity in adipose tissue was associated with a decreased uptake of FA as indicated by a decreased uptake of $\sp $C-labeled FA from labeled chylomicrons. Fatty acid uptake from labeled TG was not associated with tissue LPL activity in other tissues. Clearance of 14C-CM-TG from plasma and the half-lives of 14C-CM-TG were similar in rats fed the control diet (12% kcals as fat) or the high fat diet. These studies demonstrate that skeletal muscle, heart, adipose tissue and post-heparin plasma LPL activities can be altered by exercise and diet composition, but that changes in tissue and plasma LPL are not directly related to uptake of FA by tissues or the rate of clearance of plasma TG from chylomicrons.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Food Science

Grantor

University of Illinois at Urbana-Champaign

Date dc:date

10000-01-01

Author dc:creator

• Brown, Cecelia Mary

• Biology, Animal Physiology
• Health Sciences, Nutrition

Language dc:language

eng

Identifier

(UMI)AAI8823086

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/77464