[Insulin receptor reaction of the lamprey Lampetra fluvialis to hyperinsulinemia induced by administration of the hormone].

Insulin injections to the lamprey Lampetra fluviatilis result in prolonged and significant hyperinsulinemia, but do not decrease the number of receptors in its target cells. These findings were made in studies on the specific binding to 125I-insulin by membrane fractions of the brain and cardiac muscle in migrating and winter (fasting) lampreys. It is also suggested that no regulation of the number of the receptors by hormonal level takes place in the lamprey, which is presumably due to a low rate of internalization of hormone-receptor complexes and to a total decrease in the turnover of the receptors in a pre-spawning period.