CARDIAC TRANSENDOTHELIAL TRANSPORT OF FATTY-ACIDS

Cardiac fatty acid uptake has been postulated to be either passive or vary with the workload of the heart. Assuming an infinitely fast off rate so that the unbound capillary concentration is constant, the maximum amount of unbound nonesterified fatty acids (NEFA) that could be transported across the endothelial cells is the permeability surface area product (PS) times the arterial concentration. However, experiment showed that the passive flux of unbound fatty acids is not a major determinate of transendothial flux. The transendothelial transport of albumin is also quite low, and NEFA do not traverse the endothelial cell barrier as the NEFA-albumin complex. Thus there must exist a mechanism to facilitate the transfer of NEFA from the NEFA-albumin complex in the plasma across the endothelial cell. Further experiments suggest that an endothelial luminal surface site for albumin-palmitate augments palmitate translocation.