Technical Reference #110

110.

Quantitative Subcellular Imaging Of Glucose Metabolism Within Intact Pancreatic Islets Bennett; B.D.; Jetton; T.L.; Ying; G.; Magnusson; M.A. and Piston; D.W., Vanderbilt University, The Journal of Biological Chemistry, 271(110), (1996)
Link To Paper

Abstract:
Studies of dispersed cells have been used to infer their behavior in the intact pancreatic islet. When dispersed cells exhibit multiple metabolic glucose-response populations with different insulin secretion properties. This has led to a model for glucose-dependent insulin secretion from the islet based on a step-wise recruitment of individual cells. However previously reported synchronous and uniform Ca activity and electrical responses indicate that cell behavior within intact islets is more uniform. Therefore uncertainty remains whether cell metabolic heterogeneity is functionally important in intact islets. We have used two-photon excitation microscopy to measure and compare the glucose-induced NAD(P)H autofluorescence response in dispersed cells and within intact islets. Over 90% of cells in intact islets responded to glucose with significantly elevated NAD(P)H levels compared with less than 70% of dispersed cells. In addition all responding cells within intact islets exhibited a sigmoidal glucose dose response behavior with inflection points of 8 mM glucose. These results suggest that cell heterogeneity may be functionally less important in the intact islet than has been predicted from studies of dispersed cells and support the role of glucokinase as the rate-limiting enzyme in the cell glucose response.

Microscopic Technique
Two Photon Excitation Microscopy

Cell Type(s)
Islet