Postprandial lipaemia is associated with activation of factor VII (FVII) and efflux
of cholesterol from tissues to nascent plasma high density lipoproteins (HDL) containing
apolipoprotein A-I (apo A-I). To determine whether FVII activation and cholesterol
efflux occur together in other situations, the responses to intravenous infusion of
HDL-like apo A-I/phosphatidylcholine discs were measured in 10 healthy men. Disc infusion
(40 mg apo A-I/kg body weight) over 4 h was followed by increases in HDL cholesteryl
ester and plasma apo A-I (p <0.0001). Significant activation of FVII was apparent
during infusion in fasting subjects (p = 0.03), activated FVII averaging 123% of baseline
value by 12 h (p <0.0001). Plasma thrombin-antithrombin (TAT) complex increased to
156% of baseline level by 12 h (p >0.05) but individual responses differed considerably.
Peak TAT post-infusion was associated inversely with peak HDL triglyceride concentration
(p = 0.004). The coagulation responses to disc-infusion may be due to transfer of
phosphatidylserine to cell surfaces during cholesterol efflux.
Keywords
Factor VII - apolipoprotein A-I - high density lipoprotein - phospholipids - reverse
cholesterol transport