Chemiluminescence detection of ATP release from red blood cells upon passage through microbore tubing

A novel approach for the determination of adenosine triphosphate (ATP) released from red blood cells (RBCs) after passage through microbore capillaries is described. ATP is often released from RBCs in vessels and has been linked to the production of nitric oxide, a known vasodilator. The system described here uses a syringe pump to deliver microliter flow rates (5-15 microl min(-1)) of reagent and sample through fused silica capillary tubing of varying dimensions (25-75 microm) to a photomultiplier tube. The released ATP is characterized by the detection of chemiluminescent emission from the luciferin-luciferase reaction. The amount of ATP released is directly proportional to the number of RBCs injected into the system. Results also suggest that the amount of released ATP decreases from 6.9 microM to 1.4 microM as the tubing diameter is increased from 25 microm to 75 microm. An investigation of capillary lengths ranging from 15 to 35 cm resulted in ATP concentrations of 1.5 microM to 2.4 microM being released. Results also indicate that increases in flow rate also induce increased amounts of ATP release. These results are consistent with those of previous systems attempting to model the physiological release of ATP from red blood cells.