The Effects On Endothelial Function Of Blood Lipid Changes After Different Fat Meals In Patients With Coronary Heart Disease

Background:Most lifetime of human lies in a kind of postprandial states.Some studies have shown that postprandial lipoproteins metabolism correlate with atherosclerosis in early and progressive stage.However,the mechanism by which postprandial lipid disorders cause atherosclerosis is unknown.Endothelial dysfunction plays an important role in atherosclerosis.After a high fat meal,the level of postprandial serum triglyceride increases and postprandial endothelium-dependent vasorelaxation is impaired severely.Objective:The present study is to evaluate lipoprotein changes after a high fat meal and a low fat meal ,and its impairment of endothelium-dependent vasorelaxation in coronary heart disease(CHD).Method:Forty patients with CHD(TC < 5.2mmol/L,TG < 3.0mmol/L)was randomized into two groups. After fasting for 12 hours, one group was given high fat meal and the other was given low fat meal. Blood samples was drawn for serum total cholesterol, triglyceride, LDL-C, HDL-C in fasting state and at 2,4,5,5,7hours after a high fat meal or low fat meal. Endothelium-dependent flow-induced and endothelium-dependent nitroglycerin(NTG)-induced dilatation of the right brachial artery were measured noninvasively by high-resolution ultrasound technique at fast state and 4 hours postprandially.Results:In high fat meal group, postprandial serum triglyceride was elevated significantly. Serum triglyceride concentration increased from 1.76 ± 0.76 mmol/L preprandially to 2.26 ± 0.86 mmol/L,2.87±1.42mmol/L,2.76±1.17 mmol/L,2.25 ± 1.27 mmol/L at 2,4,5,7hours after the high fat meal respectively. Postprandial serum TC,LDL-C,HDL-C did not change significantly. Postprandial endothelium-dependent flow-induced vasorelaxation decreased from 3.38 ± 2.34% preprandially to 1.27±2.31% 4 hours postprandially(p<0.01). No changes in endothelium-dependent vasorelaxation were found. There was a significant correlation between elevation in 2-hour postprandial serum triglyceride levels and impairment in 4-hour postprandial endothelium-dependent vasorelaxation(r=0.748,p<0.01); in low fat meal group, postprandial serum triglyceride concentration was elevated slightly without significant difference(p>0.05). No changes in serum TC,LDL-C,HDL-C, endothelium-dependent flow-induced and endothelium-independent NTG-induced dilatation after the low fat meal were observed.Conclusion: Endothelium-dependent vasorelaxation were impaired in CHD after high fat meal. Impairment of endothelium-dependent vasorelaxation correlated with elevation in postprandial serum triglyceride levels. Significant increase of triglyceride-rich lipoproteins may play an important role in AS progression, plaque unstabilization , plaque rupture and acute coronary events.