Effects of Ca2+ and a phorbol ester on insulin secretion from islets of langerhans permeabilised by high‐voltage discharge

• Published in: FEBS letters 1985-10, Vol.191 (1), p.102-106
• Main Authors: Jones, Peter M., Stutchfield, Jane, Howell, Simon L.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Calcium - pharmacology; Cytosolic Ca2; Dose-Response Relationship, Drug; Electric Stimulation; Endocrine pancreas; Exocytosis; Fundamental and applied biological sciences. Psychology; High-voltage discharge; Hormones. Régulation; In Vitro Techniques; Insulin - metabolism; Insulin Secretion; Islets of Langerhans; Islets of Langerhans - drug effects; Islets of Langerhans - metabolism; Permeability; Phorbol ester; Phorbols - pharmacology; Rats; Tetradecanoylphorbol Acetate - pharmacology; Vertebrates: endocrinology
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(85)81002-4

Isolated rat islets of Langerhans permeabilised by high‐voltage discharge secreted insulin in response to elevations in Ca2+ over the range 100 nM to 10 μM Ca2+. The phorbol ester, 12‐O‐tetradecanoylphorbol 13‐acetate (TPA), had no effects on insulin secretion in the absence of Ca2+. In the presence of Ca2+ concentrations of > 10 nM, TPA produced dose‐related shifts in the Ca2+‐activation curve to lower Ca2+ concentrations, together with marked increases in the maximum secretory response to Ca2+. These results suggest that, in islets, the activation of protein kinase C is important in modulating both the sensitivity of the exocytotic mechanism to intracellular Ca2+, and the magnitude of the insulin secretory response.