Influence of Insulin and Glucagon on the Production of Glomerulopressin by Isolated Rat Liver

Summary

Isolated rats livers were perfused with Krebs-Ringer-Bicarbonate (KRB) and different doses of insulin or glucagon and with insulin plus glucagon. The isolated liver of fasted rats and of rats treated with streptozotocin were perfused with (KRB). The glomerulopressin activity of the ultrafiltrate of the liver perfusates were assayed in the tonic tension contraction (TTC) of isolated stomach fundus from rats. As glomerulopressin is known to be a glucuronide, it was inactivated with (β-glucuronidase to confirm that the effect on the stomach fundus was due to the glomerulopressin and not to an autacoid.

It was observed that glucagon increased the glomerulopressin activity of the perfusate and that this activity was independent of the dose of glucagon used. Insulin produced a decrease in the glomerulopressin activity of the perfusate, there being a log-dose relationship between insulin and glomerulopressin.

There is a dose of insulin (1,5 × 10^-5 U/min/kg) that potentiates the response to glucagon. Fasting and treatment with streptozotocin induced an increase in the glomerulopressin activity of the perfusate.

These results suggest that glomerulopressin production is influenced by glucagon and insulin, and that there is a specific ratio between these hormones that is very effective in the production of glomerulopressin.

Key-Words:

Glomerulopressin - Liver - Insulin - Glucagon - Streptozotocin-Diabetes