Acceleration of rat liver phospholipid metabolism after long-term cadmium administration

Male Wistar rats, 6 weeks old, were allowed free access to water containing cadmium chloride at a concentration of 250 ppm as cadmium (Cd) for 6 and 12 months. The growth, as measured by body weight of Cd-treated rats, was significantly retarded. Electron microscopic studies revealed the appearance of small vacuoles in the cytoplasm, and involution of the rough endoplasmic reticulum (RER) in both the liver and whole kidney. When radioactive precursors of phospholipids, H3(32)PO4 and [1(3)-H]glycerol, were injected (ip) into cd-treated rats, the incorporation of 32P into phosphatidylcholine (PC) in the liver was increased 3.2- and 5.8-fold after 6- and 12-month Cd administration, respectively, and that of 3H into PC was also increased 2.3- and 2.2-fold after 6- and 12-month Cd administration, respectively. In the kidney, however, the incorporation rates of these radioactive precursors were little affected by long-term Cd administration. In the liver of rats treated with Cd for 6 and 12 months, the activity of CDP-choline:cholinephosphotransferase was increased by 20-30% over the control. It was shown that de novo synthesis of PC, which is a major constituent of biological membranes, was accelerated by long-term Cd administration in the liver but not in the kidney. These results suggest the possibility of regenerating the membranes in damaged hepatocytes after 6 and 12 months of Cd administration.