Palmitic acid in HDL is associated to low apo A-I fractional catabolic rates in vivo

• Published in: Clinica chimica acta Vol. 378; no. 1; pp. 53 - 58
• Main Authors: Pérez-Méndez, Óscar, Álvarez-Salcedo, Paris, Carreón Torres, Elizabeth, Luc, Gérald, Arce Fonseca, Minerva, de la Peña, Aurora, Cruz Robles, David, García, José J., Vargas-Alarcón, Gilberto
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-03-2007
• Subjects: Animals; apo A-I turnover; Apolipoprotein A-I - metabolism; CETP; Cholesterol Ester Transfer Proteins - physiology; Fatty Acids, Nonesterified - analysis; HDL; Humans; Lipoprotein electric charge; Lipoproteins, HDL - analysis; Lipoproteins, HDL - chemistry; Non-esterified fatty acids; Palmitic acid; Palmitic Acid - analysis; Rabbits; HDL; CETP; Non-esterified fatty acids; apo A-I turnover; Palmitic acid; Lipoprotein electric charge
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2006.10.019

HDL becomes enriched with non-esterified fatty acids (NEFAs) in some pathologies, such as nephrotic syndrome, as well as after aerobic exercise. However, little is known about the impact of NEFAs on HDL metabolism. We investigated the effects of one NEFA, the palmitic acid, on HDL structure and catabolism.
HDL enrichment with palmitic acid (HDL
Pal) was performed by fusing phosphatidyl choline small unilamellar vesicles containing the NEFA with human HDL isolated from a pool of 5 normolipidemic plasma. HDL enriched only with phosphatidyl choline (HDL
Phl) and native HDL (HDL
Ctrl) were included as controls.
As expected, HDL
Pal surface charge density was higher than HDL
Phl and HDL
Ctrl (2014.4
±
164.8 vs. 1682.7
±
149.5 and 1758.2
±
124.3-esu/cm
2, respectively,
p
<
0.05). Both, HDL
Pal and HDL
Phl were better substrates for cholesteryl esters transfer protein (CETP) than HDL
Ctrl (% of transfer, 13.02
±
3.8 and 12.7
±
4.5 vs. 7.8
±
2.7% in 16 h, respectively,
p
<
0.05). HDL
Pal apo A-I catabolism in vivo, as performed in New Zealand white rabbits by exogenous radiolabeling, was markedly lower than that of HDL
Phl and HDL
Ctrl (fractional catabolic rate, 0.019
±
0.008 vs. 0.030
±0.005 and 0.047
±
0.003 h
−
1
, respectively,
p
<
0.001), suggesting that negative charge is inversely related to HDL-apo A-I catabolism.
Enrichment with palmitic acid increases the negative electric charge of HDL at physiological pH, contributes to decrease their catabolism, and is associated to an enhanced lipid transfer by CETP that has been related to the atherogenic process.