Effects of the protein phosphatase inhibitors okadaic acid and calyculin A on insulin release from rat pancreatic islets. |
| |
Authors: | T Tamagawa A Iguchi K Uemura H Miura K Nonogaki T Ishiguro N Sakamoto |
| |
Institution: | Third Department of Internal Medicine, Nagoya University School of Medicine, Japan. |
| |
Abstract: | The role of protein phosphatases in the regulation of insulin release from rat pancreatic islets was studied with protein phosphatase inhibitors, okadaic acid and calyculin A. Okadaic acid inhibited glucose- and glyceraldehyde-induced insulin release dose-dependently and also inhibited the potentiation of glucose-induced release either by adding forskolin, an activator of adenylate cyclase or by increasing K+ concentration to 25 mM. At a non-stimulatory concentration of 3 mM glucose, a high concentration (2 microM) of okadaic acid inhibited insulin release induced by high K+ or 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, but a low concentration (1 microM) of okadaic acid did not significantly inhibit TPA-induced insulin release. Calyculin A also inhibited glucose-induced insulin release, and the effect was greater than that of okadaic acid. The data suggest that protein phosphatases may play an important role in the regulation of insulin release. |
| |
Keywords: | |
|
|