Glucose-dependent Functional Heterogeneity In β-TC-6 Murine Insulinoma

To determine if the murine insulinoma, β-TC-6, is a suitable substitute for primary pancreatic β-cells in the study of βcell functional heterogeneity, we used three distinct functional assays to ascertain the cell line’s response to glucose or a glucose analog. These assays include: (i) a 2-NBDG uptake assay; (ii) a calcium influx assay, and; (iii) a quinacrine secretion assay. We show that a population of β-TC-6 cells endocytoses the glucose analog, 2NBDG, at different rates, has non-uniform intracellular calcium ion concentrations and releases quinacrine at different rates when challenged with glucose. We also measured the Km for β-TC-6 glucose uptake to be 46.9 mM and the Vm to be 8.36 x 10 mmole/million cells/min. These data suggest that β-TC-6 might be used as an alternative to primary pancreatic β-cells for the study of glucose-dependent β-cell functional heterogeneity. Keywords—2-NBDG, Fura-2/AM, functional heterogeneity, quinacrine.