Journal of Lipid Research, Vol 26, 930-939, Copyright © 1985 by Lipid Research, Inc.
Metabolism of n-3 polyunsaturated fatty acids and modification of phospholipids in cultured rabbit aortic smooth muscle cells
N Morisaki, T Kanzaki, Y Fujiyama, I Osawa, K Shirai, N Matsuoka, Y Saito and S Yoshida
The metabolism of the linolenic acid family (n-3) of fatty acids, e.g.,
linolenic, eicosapentaenoic, and docosahexaenoic acids, in cultured smooth
muscle cells from rabbit aorta was compared to the metabolism of linoleic
and arachidonic acids. There was a time-dependent uptake of these fatty
acids into cells for 16 hr (arachidonic greater than docosahexaenoic,
linoleic, eicosapentaenoic greater than linolenic), and the acids were
incorporated mainly into phospholipids and triglycerides. Eicosapentaenoic
and arachidonic acids were incorporated more into phosphatidylethanolamine
and phosphatidylinositol plus phosphatidylserine and less into
phosphatidylcholine than linolenic and linoleic acids. Docosahexaenoic acid
was incorporated into phosphatidylethanolamine more than linolenic and
linoleic acids and into phosphatidylinositol plus phosphatidylserine less
than eicosapentaenoic and arachidonic acids. Added linolenic acid
accumulated mainly in phosphatidylcholine and did not decrease the
arachidonic acid content of any phospholipid subfraction. Elongation-
desaturation metabolites of linoleic acid did not accumulate. Cells treated
with eicosapentaenoic acid accumulated both eicosapentaenoic and
docosapentaenoic acids mainly in phosphatidylethanolamine and the
arachidonic acid content was decreased. Added docosahexaenoic acid
accumulated mainly in phosphatidylethanolamine and decreased the content of
both arachidonic and oleic acids. The following conclusions are drawn from
these results. The three n-3 fatty acids are utilized differently in
phospholipids. The arachidonic acid content of phospholipids is reduced by
eicosapentaenoic and docosahexaenoic acids, but not by linolenic acid.
Smooth muscle cells have little or no desaturase activity, but have
significant elongation activity for polyunsaturated fatty acids.