The metabolic syndrome is often described as a group of risk factors associated with diabetes. These risk factors include, but are not limited to, such conditions as insulin resistance, obesity, high blood pressure, and oxidant stress. Here, we report on a tool that may provide some clarity on the relationship between some of these associated risk factors, especially oxidant stress and hypertension. Specifically, we describe the ability to simultaneously monitor nicotinamide dinucleotide phosphate (NADPH), reduced glutathione (GSH), and shear-induced adenosine triphosphate (ATP) release from erythrocytes using luminescence detection on a microfabricated device. The measurements are performed by delivering erythrocyte lysate (for the NADPH and GSH measurements, two analytes indicative of oxidative stress) or whole red blood cells (RBCs) (for the determination of ATP release from the cells) to an array of wells that contain the necessary reagents to generate a luminescence emission that is proportional to analyte concentration. A fluorescence macrostereomicroscope enables whole-chip imaging of the resultant emission. The concentrations of each NADPH and GSH contained within a 0.7percent erythrocyte solution were determined to be 31.06 +- 4.12 and 22.55 +- 2.47 (mu)M, respectively, and the average ATP released from a nonlysed 7percent erythrocyte solution was determined to be 0.54 +- 0.04 (mu)M. Collectively, the device represents a precursor to subsequent merging of microfluidics and microtiter-plate technology for high-throughput assessment of metabolite profiles in the diabetic erythrocyte.
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