The effects of insulin, glucose and catecholamines on some blood minerals in sheep.

Intravenous injection of insulin, 0.5 i.u./kg, was followed by a decrease in plasma magnesium. It is earlier known that insulin sometimes lowers the blood magnesium level, and the mechanism behind this effect is said to be an increased tissue uptake of magnesium. Glucose infusion did not change plasma magnesium, whereas norepinephrine and epinephrine caused a slight reduction. Insulin at the dose of 1 i.u./kg reduced plasma calcium in intact sheep. In thyroidectomized sheep the same dose caused a rise in plasma calcium. It is suggested that insulin caused hypercalcaemia in the thyroidectomized sheep by increasing the rate of bone resorption, and that the decrease in plasma calcium observed in the intact sheep was due to release of calcitonin to such an extent that the bone resorbing effect of insulin was blocked. Insulin also lowered plasma inorganic phosphorus in the thyroidectomized sheep.