Insulin: Evidence for Inhibition of Release in Spontaneous Hypocalcemia

A requirement of calcium ion for normal insulin release has been demonstrated in vivo. It was shown that subnormal amounts of immunoreactive insulin were released in response to infusions of glucose during the severe postparturient hypocalcemia that occurs in dairy cows (postparturient paresis). A diabetic glucose tolerance curve was also observed with this condition. In the presence of hyperglycemia following an infusion of glucose or that occurring naturally in postparturient paresis, a prompt and marked release of immunoreactive insulin was observed in response to an infusion of calcium borogluconate.