Figure 8. Relationship between lucigenin chemiluminescence triggered by NADH and luminol/horseradish peroxidase (HRP) chemiluminescence triggered by A23187. These signals are highly correlated (P < .001), even though they measure different aspects of cellular redox activity. Closed circles represent low-density populations of human spermatozoa recovered from the 50%:100% Percoll interface, while open circles represent high-density populations recovered from the base of the isotonic Percoll fraction. All fractions had been treated with CD45-coated magnetic beads and were free of detectable leukocyte contamination.