PALMITATE UPTAKE BY CARDIAC MYOCYTES AND ENDOTHELIAL-CELLS

The mechanisms regulating the cellular uptake of long-chain fatty acid s are poorly understood. Although there is evidence that hepatocytes f acilitate the uptake of ligands from the protein-bound fraction, it is not known whether cardiac myocytes also facilitate the uptake process . The present studies were designed to address the role of albumin in the uptake of long-chain fatty acids by cardiac myocytes isolated from adult male rats. At low albumin concentrations (1 mu M), the myocyte palmitate clearance rate did not exceed that predicted by the diffusio n-reaction model. At high albumin concentrations (300 and 600 mu M), t he clearance ratio test was used to determine whether myocytes facilit ate the uptake of palmitate. As with the low albumin concentrations, t he diffusion-reaction model accounted for the overall clearance rates. Because endothelial cells might be involved in enhancing fatty acid t ransport into myocytes, we also determined the effects of endothelial cells on palmitate uptake by cardiac myocytes. Based on cell number, t he palmitate clearance rate by endothelial cells in the presence of al bumin was only 7% of the cardiac myocyte clearance rate. Combining the endothelial cells with the myocytes did not result in any synergistic effect on the palmitate clearance rate.