Abstract 19022: Endothelial Cell Specific CD36 Deletion Reduces Uptake of Fatty Acids by the Heart
Circulating fatty acids must cross the endothelial cell (EC) barrier to supply cardiomyocytes (CM). How this occurs is unknown. Cluster of differentiation (CD) 36 is a membrane associated protein whose total body deletion leads to reduced uptake of non-esterified fatty acids by heart, skeletal muscle and adipose tissue. To determine the contribution of EC versus CM CD36 in heart lipid uptake, we floxed CD36 and created EC- and CM-specific knockout (KO) mice. CD36 mRNA was reduced >50% in the heart, lung and skeletal muscle of EC-CD36 KO mice; CM-CD36 KO mice also had an ~50% reduction of CD36 mRNA levels in the heart. Both CM- and EC-specific CD36 ablation altered heart mRNA levels of glucose transport and oxidation genes (e.g. Glut1 ~2-fold increased, PDK4 ~0.5-fold decreased); these changes were similar to those found in mice with total body CD36 deletion. Loss of EC-CD36 led to increased plasma free fatty acid levels and prevented heart lipid droplet accumulation after an overnight fast (assessed by EM and oil red O staining). Lipid droplet accumulation was less affected in CM-CD36 KO hearts. To quantify the role of CD36 in the uptake of short chain vs. long chain fatty acids we simultaneously injected mice with radiolabeled [14C]hexanoic acid and [3H]oleic acid. Compared to both floxed-CD36 and CM-CD36 KO mice, plasma clearance of oleic acid was significantly delayed, and heart and quadriceps muscle uptake of oleic acid was reduced >50% in EC-CD36 KO and total-CD36 KO mice. Hexanoic acid uptake was not decreased by either deletion. Therefore, CD36 in EC is needed for the accumulation of long chain fatty acids in the heart and appears to be required for movement of fatty acids across the EC barrier.
Author Disclosures: F. Willecke: None. N. Son: None. X. Fang: None. K. Drosatos: None. T. Pietka: None. N.A. Abumrad: None. I.J. Goldberg: None.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.