Overcoming matrix effects in the chemiluminescence determination of extracellular adenosine triphosphate in erythrocyte suspensions.

As erythrocyte-derived extracellular adenosine triphosphate (ATP) gains recognition as a key vasodilator, its accurate determination is critical. Erythrocytes' high hemoglobin content can act as an inner filter when measuring ATP concentrations by chemiluminescence. We evaluated two approaches to correct for this matrix effect: addition of cell-free hemoglobin to the ATP standards and standard addition of ATP to erythrocyte suspensions. In addition, we reduced sample hematocrit to minimize the absorbance. We conclude that extracellular ATP should be determined in erythrocyte suspensions at 0.06 to 0.004% hematocrit. This gives robust signals without matrix effects and requires only microliters of blood. Crown