Effect of marginal zinc deficiency on the morphological characteristics of intestinal nascent chylomicrons and distribution of soluble apoproteins of lymph chylomicrons.

Effects of marginal zinc depletion on the compositional and morphological characteristics of chylomicrons were investigated in adult male rats fed 3 ppm of dietary zinc, as compared with pair-fed and ad-libitum controls given 30 ppm of zinc for 6 to 8 wk. Lymph was collected by cannulating the intestinal lymphatic duct during infusion of a 1:1 mixture of Intralipid and 150 mM NaCl via a duodenal catheter. Lymph chylomicrons were isolated by ultracentrifugation and further purified by agarose column chromatography. A marginal level of zinc deficiency produced decreases in the relative concentrations of apolipoproteins C and E, with an increase in apoprotein A-I and no change in apoprotein A-IV and no significant alterations in the lipid components. Nascent chylomicrons in the intestinal absorptive cells were irregular and larger in shape and size, as determined by light and electron microscopy. The present results suggest that the changes in chylomicron apoproteins produced by zinc deficiency are due in part to postsynthetic modification of intestinal chylomicrons upon their release into the lymph.