In this application, we propose to study several aspects of intestinal lipoprotein metabolism. First, we will evaluate to in depth the role of the various parts of the intestine in the degradation of low density lipoprotein (LDL). A unique aspect of this work will be the use of antireceptor antibodies to study LDL metabolism. The distribution of receptors along the GI tract will be determined by immunohistochemistry and direct binding. The presence of receptors in crypt and villous cells and the subcellular location of the receptors will also be determined. Regulation of receptor number under the influence of altered serum level and dietary and pharmacologic perturbation will be studied as well as the effect of malignant degeneration on receptor number. In other studies, the role of the LDL receptor in high density lipoprotein metabolism will be studied. The question of whether there is transport of cholesterol in excess of apoprotein will be addressed.
