Apoptosis in the monkey small intestinal epithelium: Structural and functional alterations in the mitochondria

Our earlier studies have shown apoptosis in the villus tip cells of the mon key small intestinal epithelium. Because mitochondria have been implicated in the apoptotic process, this study looked at the function and lipid compo sition of mitochondria isolated from apoptotic villus tip cells and compare d it with middle and crypt cells. Decreased MTT reduction and respiratory c ontrol ratio, increased swelling and altered mitochondrial enzyme activitie s were seen in the villus tip cell mitochondria when compared to other cell s. The lipid composition of the villus tip mitochondria were different from the other mitochondria. A decrease in phosphatidylethanolamine and phospha tidylinositol and an increase in phosphatidic acid was seen in these mitoch ondria. Fatty acid composition analysis showed more unsaturated fatty acids in the free fatty acid and phospholipid fraction in villus tip cell mitoch ondria as compared to other cells. These studies suggest that in the monkey small intestinal epithelium, apoptotic process is associated with function al and structural alterations in the mitochondria. (C) 1999 Elsevier Scienc e Inc.