Activation of coagulation factor VII during alimentary lipemia.
Silveira A., Karpe F., Blombäck M., Steiner G., Walldius G., Hamsten A.
Dietary studies have established a connection between plasma lipoproteins and coagulation factor VII. The present study was undertaken to specifically examine whether factor VII is activated during alimentary lipemia and to investigate the relations of factor VII mass and activity state with fasting and postprandial lipoproteins and free fatty acids (FFAs). Factor VII levels were therefore determined in plasma samples taken before and after intake of a standardized, oral fat load of a mixed-meal type in 33 men (mean age +/- SD, 48.8 +/- 3.2 years) with a previous myocardial infarction at a young age and 10 healthy, age-matched control subjects. A panel of methods for factor VII determination was used to ensure that changes in all potentially existing forms of the factor during alimentary lipemia would be included. Substantial activation of factor VII was found to occur during alimentary lipemia, whereas the number of factor VII molecules remained constant or even appeared to decrease after the test meal. Activation of factor VII was more pronounced in control subjects than patients, and the proportion of activated factor VII molecules was higher in control subjects. Interestingly, factor VII activation, which correlated quantitatively with the degree of postprandial triglyceridemia, seemed to be related to FFA production during lipolysis of triglyceride-rich lipoproteins that were generated in response to fat intake. Postheparin plasma lipoprotein lipase activity was lower in patients, which could offer one explanation why factor VII activity was lower during alimentary lipemia in these subjects despite their exaggerated postprandial triglyceridemia. Thus, activation of coagulation factor VII during alimentary lipemia may result in a procoagulant state that is likely to promote the formation of a coronary thrombus in individuals with established coronary artery disease.