Indication for a specific interaction of fatty acids with a liver sinusoidal plasma membrane carrier.

To evaluate whether fatty acids interact specifically with plasma membrane proteins, binding of [3H]oleate to rat liver plasma membranes was determined after exposure of the plasma membranes to temperatures of 40 to 95 degrees C for 15 min. Starting at 50 degrees C, membrane binding of [3H]oleate gradually decreased, reaching at 95 degrees C a 58.2% inhibition of binding compared to control values obtained at 18 degrees C. Another criterion of specific interaction with a membrane transport protein was the observation that two different long chain fatty acids, palmitate and oleate, compete for uptake in the experimental system of the isolated perfused rat liver. Both observations support the hypothesis that hepatocellular uptake of fatty acids represents a carrier mediated transport mechanism and not simple diffusion.