Postprandial changes in apolipoprotein(a) concentration of triglyceride-rich lipoproteins can be reproduced by in vitro incubation: implications for underlying mechanism

• Published in: Atherosclerosis Vol. 103; no. 2; pp. 139 - 147
• Main Authors: Sullivan, D.R., Lam, C.W.K., Jessup, W., Dean, R.T., Hensley, W.J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier Ireland Ltd 01.11.1993; Elsevier
• Subjects: Adult; Aged; Apolipoprotein(a); Apolipoproteins A - metabolism; Atherosclerosis; Atherosclerosis (general aspects, experimental research); Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Dietary Fats - administration & dosage; Female; Humans; In Vitro Techniques; Lipoproteins - blood; Male; Medical sciences; Middle Aged; Postprandial lipoprotein metabolism; Triglyceride-rich lipoproteins; Triglycerides - blood; TRL apo(a); Triglyceride-rich lipoproteins; TRL apo(a); Apolipoprotein(a); Postprandial lipoprotein metabolism; Atherosclerosis; Vascular disease; Human; Postprandial; Cardiovascular disease; Metabolic diseases; Exploration; Lipoprotein; Metabolism; Triglyceride
• ISSN: 0021-9150; 1879-1484
• DOI: 10.1016/0021-9150(93)90257-U

We investigated the reciprocal changes in apolipoprotein(a) concentration in the lipoprotein of d > 1.006 and the triglyceride-rich lipoprotein (TRL) fractions of plasma which occur in vivo following fat ingestion. Twenty fasting subjects were studied before and 4 h after a fat-rich meal. In 75% of cases, in vitro incubation of the postprandial (4-h) TRL with autologous fasting (0-h) lipoproteins of d > 1.006 resulted in further substantial (>5% total) reciprocal changes in apo(a) concentration of the 2 fractions. The increase in re-isolated postprandial TRL apo(a) was 25.1% ± 5.1% of the total apo(a), compared to the insignificant increase (0.1% ± 0.1%) in re-isolated fasting TRL. Most of the further increase in 4-h TRL apo(a) (94% ± 4%) could be achieved by incubation with the corresponding 4-h chylomicron fraction (CM) alone. The re-isolated 4-h TRL apo(a) concentration correlated positively with 4-h plasma TG concentration ( r = 0.65, P < 0.01) and other indices of postprandial lipaemia. In vitro incubation of pooled serum lipoproteins of d > 1.006 with serial dilutions of nascent CM obtained from chylous ascitic fluid revealed that the reciprocal changes in apo(a) concentration exhibit a curvilinear relationship with the concentration of CM triglyceride which plateaued round 7 mmol/1 in this instance. We conclude that the reciprocal changes in apo(a) concentration between TRL and lipoproteins of d > 1.006 which occur in the postprandial phase are quantitatively significant and largely represent a redistribution process rather than de novo synthesis because they can be reproduced by in vitro incubation.