Elsevier

Metabolism

Volume 24, Issue 8, August 1975, Pages 943-952
Metabolism

Apoliporoteins in human pregnancy

https://doi.org/10.1016/0026-0495(75)90086-4Get rights and content

Abstract

Apolipoproteins are important in the structure and metabolism of lipoproteins, and alterations in levels of apoproteins or in their interrelations occur in some forms of hyperlipemia. Pregnancy is regularly accompanied by hyperlipoproteinemia, but while data on lipoprotein lipids is available, the apolipoproteins have not been studied. To characterize the lipemia of pregnancy more completely, we studied some of the apolipoproteins in plasmas of pregnant women.

Thirty-eight normal fasting women were studied between the 18th and 39th weeks of gestation and again 23 ± 17 weeks after delivery. Eight additional women were sampled every 4–6 wk during the second and third trimesters of gestation. Plasma and lipoprotein lipids were assayed by standard procedures and Apolipoprotein B (ApoB) was measured by radioimmunoassay. The interrelations of Apolipoprotein A (ApoA) in high-density lipoprotein (HDL) and of Apolipoprotein C (ApoC) in very-low-density lipoprotein (VLDL) were assessed by disc gel electrophoresis in four women during the last trimester of gestation and again 6–8 mo post partum and in four nongravid controls.

Gestational triglycerides (TG) and cholesterol (Chol) were elevated in 95% of the pregnant women. TG in lipoproteins rose progressively during gestation, with VLDL-TG rising the most. Low-density lipo-protein (LDL) and HDL became enriched by TG relative to other components. Total- and VLDL-ApoB increased, while LDL-ApoB remained unchanged, resulting in a change in the density distribution of ApoB. (VLDL-ApoB × 100/total ApoB rose from 3.6% to 6.7%, P < 0.02). The accumulation of TG-rich LDL and the increases of VLDL-ApoB may be the result of changes in the rates of secretion or intravascular catabolism of VLDL. Which process is altered remains to be determined.

The relative amounts of ApoC-II and ApoC-III in VLDL and the ApoA-IApoA-II ratios in HDL were unchanged in pregnancy. These results differ from those seen following high-carbohydrate diets.

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    Supported in part by USPHS contract N01-HL-2-2916-L of the Lipid Research Clinics Program, and grant R01 HL15308-02 of the National Heart and Lung Institute.

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