Changes of
lipoprotein composition have been mainly reported in conditions of
sepsis. This study characterized compositional changes in
LDL and HDL during the
acute phase response following cardiac surgery with
cardiopulmonary bypass. Twenty-one patients undergoing cardiac surgery were included in this study. Blood samples were drawn before operation and on day 2 post-surgery. In parallel to plasma
lipids and
antioxidant status,
lipoproteins were analyzed for
lipid,
apolipoprotein (apo),
hydroperoxide and
alpha-tocopherol content. Beyond decreases in
lipid concentrations and
antioxidant defenses, cardiac surgery induced substantial modifications in plasma
lipoproteins.
ApoB decrease in
LDL fraction (-46%; P < 0.0001) reflected a marked reduction in the circulating particle number.
LDL cholesteryl ester content relative to
apoB concentration remained unchanged post-surgery while
triglyceride (+113%; P < 0.001), free
cholesterol (+22%; P < 0.05) and
phospholipid (+23%; P < 0.025) were raised relative to
apoB indicating increased particle size. In HDL, an abrupt rise of apoSAA (P < 0.05) was observed together with a decrease of apoA1 (-22%; P < 0.005).
Cholesteryl ester content in HDL fraction decreased in parallel to apoA1 concentration while
triglycerides, free
cholesterol and
phospholipids increased relative to apoA1. In contrast to unchanged
alpha-tocopherol content,
hydroperoxide content was increased in
LDL and HDL. By comparison to
sepsis, cardiac surgery induces a comparable reduction in circulating
LDL but a more limited decrease in HDL particles. Furthermore, in contrast, cardiac surgery induces an increase in polar and non-polar
lipids, as well as of particle size in both
LDL and HDL.