EFFECT OF MAGNESIUM-DEFICIENCY ON TRIACYLGLYCEROL-RICH LIPOPROTEIN AND TISSUE SUSCEPTIBILITY TO PEROXIDATION IN RELATION TO VITAMIN-E CONTENT

Given the current interest in the cardiovascular complications of Mg d eficiency, the aim of the present experiment was to investigate the ef fect of Mg deficiency on the time-course of Lipoprotein oxidation and to assess whether short-term Mg deficiency results in vitamin E deplet ion that predisposes lipoproteins and tissues to subsequent oxidation. Weanling rats were pair-fed for 8 d with control and Mg-deficient die ts respectively, Plasma triacylglycerol and alpha-tocopherol levels we re significantly greater in Mg-deficient rats compared with control an imals, The increase in plasma apolipoprotein B concentration indicated that a corresponding increase in plasma triacylglycerol-rich lipoprot eins (TGRLP) occurred in Mg-deficient animals, Hyperlipaemia was assoc iated with modifications in the composition of TGRLP, The proportion o f triacylglycerols was elevated whereas that of cholesterol and protei n was reduced, and Mg deficiency resulted in a slight significant redu ction in alpha-tocopherol content. When the TGRLP fractions were subje cted to in vitro Cu-induced oxidation the lipoprotein fractions from M g-deficient rats were more susceptible to oxidative damage than Lipopr otein fractions from control rats, Mg deficiency did not modify the al pha-tocopherol content of liver, heart and skeletal muscle, However, a fter exposure of tissue homogenates to Fe-induced Lipid peroxidation, thiobarbituric acid-reactive substances were significantly higher in t issues from Mg-deficient rats compared with those from control rats, T hese results complement previous findings, showing that Mg deficiency increases the susceptibility of TGRLP and tissues to peroxidation and suggest that oxidative damage is not the result of a decrease in vitam in E antioxidant status.