Experimental biliary obstruction of rat. Initial changes in the structure and lipid content of erythrocytes

The bile duct was ligated and the resulting changes in the plasma and erythrocyte lipid composition and in the shape of erythrocytes were observed. Electron microscopy at 8th hour after ligation revealed the appearance of spur cells, and on the 7th day target cells began to be observed. The appearance of spur cells was considered to be a reflection of abrupt increases in bile acid and bilirubin levels in the plasma. The conversion of spur cells to target cells which was observed was accompanied by increased levels of cholesterol and phosphatidylcholine in the erythrocytes. Plasma phosphatidylcholine and cholesterol levels were increased immediately after the commencement of ligation. On the other hand, erythrocyte phosphatidylcholine and cholesterol levels only gradually increased when compared to those in plasma, and the maximum value was observed from the 5th to the 7th day. The fatty acid composition of the increased plasma phosphatidylcholine after ligation resembled that of phosphatidylcholine in bile. On the other hand, the fatty acid composition of erythrocyte phosphatidylcholine changed remarkably between the 1st and 3rd days after bile duct ligation. These changes were also reflected by those of phosphatidylcholine in bile. These results led to the conclusion that the appearance of target cells observed in the present study was due to the accumulation of erythrocyte lipids which derived from bile. This is the first report on experimentally induced target cells and the mechanism for their appearance that seems applicable for humans.