Date of Award
Doctor of Philosophy
Genetics, Development and Cell Biology
Increased consumption of polyunsaturated fatty acids (FA) has been associated with decreased risk of cardiovascular disease in man. Platelets have been theorized to play a role in the development of atherosclerotic plaques. Two rat feeding studies are reported delineating the effect of feeding diets constant in fat and cholesterol content, and differing in the FA composition of the fat fed, on platelet metabolism. A survey of young men consuming self-selected diets with the same measures determined is also reported;The first study reports the effects of feeding rats diets providing 30% of Kcal (en%) as fat (beef tallow and corn oil) and 3.0, 4.5, 6.0, or 7.5 en% linoleate with exogenous cholesterol added as required to provide equal cholesterol content in all diets, on platelet FA and cytosolic free ionized calcium ((Ca[superscript]++][subscript] i) regulation of thromboxane synthesis (TX). The percentage linoleate in platelet FA rose linearly with increasing dietary linoleate. No measure of (Ca[superscript]++][subscript] i or TX was changed by differing dietary linoleate; indicating that the platelet FA composition changes effected by these diets did not change regulation of (Ca[superscript]++][subscript] i of TX;The second study reports the effects of feeding diets similar to those fed in the first study, with the addition of a diet providing 9.0 en% linoleate, on platelet FA, net phospholipase A[subscript]2 activity (PLA), and TX. The linoleate in platelet FA rose with dietary linoleate. PLA and TX decreased as en% dietary linoleate rose from 4.5-9.0. The concomitant changes in PLA and TX suggest that membrane FA composition controls PLA and TX, when diets provide from 4.5-9.0 en linoleate;A survey of 20 to 34 year old male humans consuming self-selected diets used three 24-hour food intake records to determine the usual fat and linoleate intakes. Data were grouped by linoleate intake into low (2.5-5.0 en%, LL), medium (5.0-8.0 en%, ML), and high (8.0-11.1 en%, HL) linoleate intake groups. Platelet (Ca[superscript]++][subscript] i, FA, PLA, and TX were measured. The LL group had lower platelet linoleate percentages than the ML and HL groups, which were not different from each other. Platelet linoleate was correlated with dietary linoleate from 2.5-8.0 en%; there was no correlation when dietary linoleate was greater than 8.0 en%. No differences in platelet (Ca[superscript]++][subscript] i or PLA were found due to dietary linoleate grouping. Platelet TX was lowest in the ML group. PLA and TX were lower than the same measures in rat platelets, although a correlation between the two was found, as in rats. Regulation of PLA and TX in humans is different from that in rats. Medium linoleate intake (5-8 en%) is recommended to promote lower TX.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Barbara Minkema Krumhardt
Krumhardt, Barbara Minkema, "Dietary lipid effects on platelet metabolism " (1989). Retrospective Theses and Dissertations. 9064.