Dissociation Between Changes in Cytoplasmic Free Ca2+ Concentration and Insulin Secretion as Evidenced from Measurements in Mouse Single Pancreatic Islets
Abstract
Simultaneous measurements of cytosolic free Ca2+ concentration and insulin release, in mouse single pancreatic islets, revealed a direct correlation only initially after stimulation with glucose or K+. Later, there is an apparent dissociation between these two parameters, with translocation of alpha and epsilon isoenzymes of protein kinase C to membranes and simultaneous desensitization of insulin release in response to glucose. Recovery of insulin release, without any concomitant changes in cytosolic free Ca2+ concentration, after addition of phorbol 12-myristate 13-acetate, okadaic acid, and forskolin supports the notion that the desensitization process is accounted for by dephosphorylation of key regulatory sites of the insulin exocytotic machinery.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- October 1995
- DOI:
- 10.1073/pnas.92.21.9712
- Bibcode:
- 1995PNAS...92.9712Z