Possible Role of Phosphatidylinositol Turnover in Insulin Release from Isolated Rat Pancreatic Islets

Summary

We have previously reported occurrence of Ca²⁺-activated, phospholipid-dependent protein kinase (referred as protein kinase C) in the rat pancreatic islets. It has been suggested that unsaturated diacylglycerol which results from hydrolysis of Phosphatidylinositol by phospholipase C-like enzyme activates protein kinase C. Therefore, we studied the effect of exogenous phospholipase C on insulin release from isolated islets of rat pancreas. Bacterial phospholipase C enhanced insulin release induced by glucose in a dose dependent manner. The effect, however, was decreased in the islets pretreated with colchicine. Both phospholipase C and glucose caused an increase in 32p incorporation into Phosphatidylinositol. These results indicate that phospholipid metabolism is linked to the insulin release mechanism.

Key-Words:

Phospholipase C - Phosphatidylinositol - Insulin - Islet - Colchicine