title: Palmitic acid in HDL is associated to low apo A-I fractional catabolic rates in vivo.
abstract: BACKGROUND
  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.
  
  
  METHODS
  HDL enrichment with palmitic acid (HDLPal) 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 (HDLPhl) and native HDL (HDLCtrl) were included as controls.
  
  
  RESULTS
  As expected, HDLPal surface charge density was higher than HDLPhl and HDLCtrl (2014.4+/-164.8 vs. 1682.7+/-149.5 and 1758.2+/-124.3-esu/cm2, respectively, p<0.05). Both, HDLPal and HDLPhl were better substrates for cholesteryl esters transfer protein (CETP) than HDLCtrl (% of transfer, 13.02+/-3.8 and 12.7+/-4.5 vs. 7.8+/-2.7% in 16 h, respectively, p<0.05). HDLPal apo A-I catabolism in vivo, as performed in New Zealand white rabbits by exogenous radiolabeling, was markedly lower than that of HDLPhl and HDLCtrl (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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Physiology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico. opmendez@yahoo.com
authors.forename: Oscar
authors.initials: O
authors.lastname: Pérez-Méndez
authors.forename: Paris
authors.initials: P
authors.lastname: Alvarez-Salcedo
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Carreón Torres
authors.forename: Gérald
authors.initials: G
authors.lastname: Luc
authors.forename: Minerva
authors.initials: M
authors.lastname: Arce Fonseca
authors.forename: Aurora
authors.initials: A
authors.lastname: de la Peña
authors.forename: David
authors.initials: D
authors.lastname: Cruz Robles
authors.forename: José J
authors.initials: JJ
authors.lastname: García
authors.forename: Gilberto
authors.initials: G
authors.lastname: Vargas-Alarcón
mesh_terms: D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism*; D053480:Cholesterol Ester Transfer Proteins / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D006801:Humans; D008075:Lipoproteins, HDL / Q000032:analysis / Q000737:chemistry*; D019308:Palmitic Acid / Q000032:analysis*; D011817:Rabbits
chemical_list: D016632:Apolipoprotein A-I; D053480:Cholesterol Ester Transfer Proteins; D005230:Fatty Acids, Nonesterified; D008075:Lipoproteins, HDL; D019308:Palmitic Acid