AJP - Heart and Circulatory Physiology, Vol 265, Issue 1 83-H90, Copyright © 1993 by American Physiological Society
Magnesium influences incorporation of [3H]arachidonic acid in perfused rabbits hearts
M. T. Weis
Department of Pharmacology, Philadelphia College of Pharmacy and Sciences, Pennsylvania 19104.
Ca(2+)-free perfusion of rabbit hearts produces a 50% loss of tissue Ca2+
and Mg2+ and results in reduced incorporation of arachidonic acid into
tissue lipids. This work was undertaken to determine whether the reduced
incorporation was specific for arachidonic acid and whether it was
correlated to the loss of either (or both) cation(s). Single 170-pmol bolus
doses of [3H]arachidonic or [3H]oleic acid were given to perfused hearts
with or without Ca2+ in the perfusate. The experiment was terminated, and
the lipids were extracted 1-15 min after administration of label. At all
time points, significantly less arachidonate was incorporated into total
tissue lipids in the absence of than in the presence of Ca2+. The presence
or absence of Ca2+ had no effect on the incorporation of oleate. When
[3H]arachidonate was administered to hearts perfused with buffer containing
104 mM Li+ and 35 mM Na+ (which reduces tissue Mg2+ by approximately 25%
and increases tissue Ca2+ by approximately 35%), the incorporation into
lipids was reduced from 0.882 +/- 0.0739 to 0.598 +/- 0.0722 pmol/mg lipid
(P < 0.05; n = 6). The incorporation of [3H]oleate during 104 mM Li+ and
35 mM Na+ was not different from control. These data suggest that the
incorporation of arachidonic, but not oleic, acid into tissue lipids is
dependent on the tissue Mg2+ content.
