The ethyl ester of dihomo-gamma-linolenic acid (20:3omega6) (1 g/kg/day) was fed to rabbits for 25 days. Plasma lipids and platelet aggregation were analyzed on day 1, 11, 16, 21 and 26. 2. All plasma lipid classes were greatly enriched with 20:3omega6. Arachidonic acid levels were elevated to a smaller extent. The different platelet phospholipid fractions analyzed were also highly enriched with 20:3omega6, whereas the arachidonic acid content in platelet phospholipids was significantly lower than in control animals. 3. The excretion of 7 alpha-hydroxy-5,11-diketotetranorprostane-1,16-dioic acid, the major urinary metabolite of prostaglandin E1 and E2 was increased 4.6 fold by the treatment. 4. Platelet aggregation in response to ADP, collagen and arachidonic acid did not differ at any time betweeen 20:3omega6 treated rabbits and controls. 5. It is concluded that prostaglandin E biosynthesis can be increased by enriching the prostaglandin precursor pool. Platelet aggregation in vitro is not altered by feeding ethyl 20:3omega6.
