Figure 5.

Real-time measurements using the reusable ECPA cycle for quantitative insulin detection in biological samples. (A) Cyclic methodology for reusable ECPA (discussed in text). (B) Integrated signal traces during real-time monitoring of insulin secretion from as few as five living pancreatic islets. Islets were transitioned from basal glucose (3 mM) to stimulatory glucose (11 mM) at the points labeled with asterisks (*). (C) Insulin secretion rates were quantified via calibration. Islets responded to glucose increases with the expected spikes of insulin secretion; increases from tens to hundreds of pg islet^–1 min^–1 matched well with previous reports. (D) Insulin quantitation in unspiked serum from two different C57BL/6 mice was accomplished through standard addition methods made possible by reusable ECPA.