This may explain another aspect of the Omega-6 rich vegetable oils'
ill effects ...  Should we be getting AA, if any, directly from the
meat like the cat then?

Taka

Arteriosclerosis, Thrombosis, and Vascular Biology. 1982;2:380-389

Linoleic acid metabolism and prostaglandin production by cultured
bovine pulmonary artery endothelial cells

TL Kaduce, AA Spector and RS Bar

When bovine pulmonary artery endothelial cells are cultured in a
medium supplemented with linoleic acid, their capacity to produce
prostacyclin (PGI2) is reduced by about 60%. This reduction occurs
when PGI2 formation is stimulated by the addition of either the
calcium ionophore A23187 or arachidonic acid. In addition,
supplementation with linoleic acid reduced the production of
prostaglandin E2 and F2 alpha from 1-14C- arachidonic acid by more
than 50%. The capacity of cultured bovine pulmonary vein and aortic
endothelial cells to convert extracellular arachidonic acid into PGI2
also was reduced by about 50% when the growth medium was supplemented
with linoleic acid. Although bovine pulmonary artery endothelial cells
incorporated large amounts of 1-14C- linoleic acid into cellular
phospholipids and triglycerides, a maximum of only 2.3% of the
radioactivity was converted to arachidonic acid in 24 hours. The most
prevalent radioactive metabolite was eicosadienoic acid, the
elongation product of linoleic acid. As compared with linoleic acid,
the bovine endothelial cells incorporated 30% more 1-14C- arachidonic
acid into phospholipids and 60% more into triglycerides. When the
growth medium was supplemented with linoleic acid, the percentage of
this fatty acid in cellular lipids increased 3- to 4.5- fold and
eicosadienoic acid accumulated, accounting for up to 9% of the
cellular fatty acids. This increase was accompanied by a 30% to 45%
reduction in arachidonic acid. These findings, together with our
previous results with human umbilical vein endothelium, suggest that
an inability to convert large amounts of linoleic to arachidonic acid
and a suppressive effect of linoleic acid enrichment on prostaglandin
production may be general properties of endothelial cells.

http://atvb.ahajournals.org/cgi/content/abstract/2/5/380