Insulin Binding to Liver Cells: A Simple and Useful In Vivo Model

Summary

Insulin binding to rat liver cells was studied in vivo, by I.V. injection of (¹²⁵I)-labelled hormone either alone or together with different amounts of unlabelled insulin.

Native insulin competes with the tracer in a manner similar to the one observed in the in vitro preparation. Prolactin, bovine growth hormone or glucagon were unable to displace labelled insulin from its binding sites.

The hypoglycemic effect of various amounts of native insulin was measured and correlated to the binding studies.

It was found that maximal insulin-induced hypoglycemia occurs at an insulin concentration at which only about 12 % of the measurable receptors are occupied.

Key-Words

Receptors - Insulin - Hypoglycemia - Liver Receptors