Inhibitory effect of sulfonylureas on protein phosphatase activity in rat pancreatic islets
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1432-5233
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| Keywords: |
Key words Protein phosphatase ; Sulfonylurea ; Protein phosphorylation ; Intracellular signals
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| Source: |
Springer Online Journal Archives 1860-2000
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| Topics: |
Medicine
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| Notes: |
Abstract We have measured protein phosphatase (PP) activity in crude homogenates as well as in the total 105,000×g supernatant and precipitate fractions from normal rat pancreatic islets. On the basis of the inhibition produced by either 1 nM or 1 µM okadaic acid, both PP1 and PP2A activity were present in crude islet homogenates in equivalent proportions (53% and 47%, respectively); PP1 was the main activity present in the precipitate, whereas in the supernatant it was PP2A. Tolbutamide, glybenclamide and glyclazide significantly decreased PP activity in islet homogenates in a dose-dependent manner, with a K i0.5 value that in the case of glybenclamide correlated with its K d for binding site, its EC50 on KATP channel, and its EC50 on insulin release. These data indicate that PPs play a role in the control of insulin secretion and suggest a further possible target for sulfonylureas within their overall action as insulin secretagogues.
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| Type of Medium: |
Electronic Resource
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| URL: |