Related Experiment Videos
Dissociation between changes in cytoplasmic free Ca2+ concentration and insulin secretion as evidenced from
S V Zaitsev1, S Efendić, P Arkhammar
1Rolf Luft Center for Diabetes Research, Department of Molecular Medicine, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
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.