In vivo and in vitro effects of magnesium deficiency on hepatic haptoglobin mRNA levels.

We previously showed that haptoglobin (Hp) was increased in the plasma of dietary magnesium (Mg)-deficient rats. The present study was performed to examine the effects of dietary Mg-deficiency and Mg2+ deficit in culture medium on Hp mRNA levels in liver and isolated hepatocytes, respectively. The Hp mRNA level in the liver increased significantly from day 10 to day 30 in rats on a Mg-deficient diet (Mg; 0.001 per cent). In the cultured hepatocytes, lowering the Mg2+ level in the culture medium from 0.92 mM to 0.46 mM did not affect the Hp mRNA level of hepatocytes. When IL-1beta or IL-6 was added to the culture medium, the Hp mRNA level increased much more in the hepatocytes cultured in low Mg2+ medium (Mg2+; 0.46 mM) than in those cultured in the control Mg2+ medium (Mg2+; 0.92 mM). These results suggest that the increase in plasma Hp level during dietary Mg deficiency depends on the increase in Hp mRNA level in the liver, and that this increase in mRNA is not only directly correlated with a low Mg level in plasma, but also indirectly correlated with cytokines.