title: Hyperglycemia-induced hyperinsulinemia acutely lowers plasma apolipoprotein B but not lipoprotein (a) in man.
abstract: Acute hyperinsulinemia lowers plasma apolipoprotein B (apo B) and triglycerides by suppressing hepatic lipoprotein secretion and probably by enhancing catabolism of triglyceride-rich lipoproteins, but the effect of acute hyperinsulinemia on the plasma lipoprotein(a) (Lp(a)) level is unclear. We measured plasma triglycerides, cholesterol, apo B and Lp(a) in response to 3 h hyperglycemia-induced hyperinsulinemia (blood glucose clamped at 10 mmol/l) in 16 subjects (eight women and eight men). In a control experiment saline was infused in another group of seven men. After 3 h of hyperinsulinemia plasma triglycerides decreased by 29 +/- 14% (mean +/- S.D., P < 0.001) and this fall differed from the unchanged triglyceride level during saline infusion (P < 0.001). Plasma cholesterol fell by 8 +/- 5% (P < 0.001), which was different from the unchanged cholesterol during saline infusion (P < 0.02). Plasma apo B decreased by 9 +/- 8% (P < 0.001), which was again different from the minor fall in apo B (3 +/- 2%) during saline infusion (P < 0.02). However, plasma Lp(a) remained unchanged during hyperinsulinemia (change 8 +/- 15%, n.s.), as well as during saline infusion (change 5 +/- 15%, n.s.). The % change in apo B exceeded the % change in Lp(a) during hyperinsulinemia (P < 0.01). Baseline Lp(a) was inversely correlated with first phase insulin secretion (P < 0.05), but its level during the clamp was not related to insulin sensitivity. This study demonstrates that acute hyperglycemia-induced hyperinsulinemia has a different effect on plasma apo B and Lp(a) in healthy subjects. The present data support the notion that Lp(a) is metabolized differently from triglyceride-rich lipoproteins.
authors.affiliation: Department of Endocrinology, University Hospital Groningen, The Netherlands.
authors.forename: S C
authors.initials: SC
authors.lastname: Riemens
authors.forename: J J
authors.initials: JJ
authors.lastname: Ligtenberg
authors.forename: R P
authors.initials: RP
authors.lastname: Dullaart
mesh_terms: D000328:Adult; D001055:Apolipoproteins B / Q000097:blood*; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood; D006946:Hyperinsulinism / Q000097:blood*; D007328:Insulin / Q000097:blood; D017270:Lipoprotein(a) / Q000097:blood*; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood
chemical_list: D001055:Apolipoproteins B; D008078:Cholesterol, LDL; D007328:Insulin; D017270:Lipoprotein(a); D014280:Triglycerides; D002784:Cholesterol; D005947:Glucose