Effects of parenteral pharmacological magnesium loading on insulin secretion in experimental thyrotoxicosis

Thyrotoxicosis is characterised by decreased magnesium pool and also insulin resistance. The present study is evaluating the parameters of glucose metabolism under pharmacological magnesium loading in experimentally induced thyrotoxicosis, in rats. Insulin secretion was significantly increased in thyrotoxicosis compared to controls, expressing probably the status of insulin resistance due to thyroxine excess. After intraperitoneal magnesium infusion, plasma magnesium reached pharmacologically high concentrations and insulin secretion decreased significantly, but this decrease was not accompanied by alterations of glucose homeostasis. In controls, we also found a tendency towards the decrease of insulin secretion after magnesium loading, but it did not reach statistical significance. Thus, insulin secretion seems more sensitive to the inhibitory effects of magnesium overload in experimental thyrotoxicosis.