Influence of short term dietary supplementation of different lipids on aggregation and arachidonic acid metabolism in rabbit platelets.

Semisynthetic diets containing 8% by weight of either corn oil or butter were fed to male New Zealand rabbits for three weeks. The plasma cholesterol values were determined, the threshold concentrations for aggregation of platelet rich plasmas were measured for collagen and Na arachidonate, and the conversion of 14C arachidonic acid to thromboxane B2 and hydroxy fatty acids (HETE and HHT) at 10, 20 and 40 microM substrate concentrations were studied. The thresholds for arachidonate induced aggregation were lower and the amplitudes of collagen induced aggregations were greater in the butter fed than in the corn oil fed rabbits. Conversions of arachidonic acid to thromboxane B2 but not to hydroxy fatty acids were greater in the butter fed rabbits at 10 and 20 microM substrate. The observed changes were accompanied by only slight modifications of plasma cholesterol levels.