Changes in Bioavailability and Tissue Distribution of Copper Caused by Magnesium Deficiency in Rats

The effect of an Mg-deficient diet (200 mg of Mg/kg of feed) on the bioavailability of dietary Cu and the concentration of the cation in plasma, whole blood, skeletal muscle, kidney, heart, and liver of Wistar rats after 7, 35, 49, and 70 days was studied. The Mg-deficient diet significantly increased the amount of Cu absorbed during the 10th (final) week of the experiment. A direct linear correlation was found between Cu absorbed and Cu retention (balance) (pair-fed control r ) 0.98, p < 0.001; Mg-deficient rats r ) 0.64, p < 0.001). Mg deficiency significantly reduced Cu content in whole blood on all sampling days and increased liver Cu from day 35 until the end of the experiment. Plasma, muscle, and renal Cu levels were significantly increased only at the end of the study (day 70). However, there was a significant decrease on day 70 in Cu content in heart tissue. These findings show that chronic Mg deficiency increases Cu absorption and the concentrations of this mineral in plasma, muscle, kidney, and liver. Under the experimental conditions used in this study, absorption appears to play a significant role in the regulation of the tissue distribution of Cu.