NO induces higher apoptotic cell death in APO-S than in APO-R Jurkat cells. (A) Time-dependent apoptosis induced by NO donor GTN (0.2 mmol/L) in APO-S and APO-R Jurkat cells up to a time period of 48 hours. (B) Concentration-dependent apoptosis stimulated by GTN in APO-S and APO-R Jurkat cells after 24 hours of incubation. Percentage of apoptotic cells was measured by the DNA-release assay using treatment with a hypotonic propidium iodide solution at 4°C overnight in the dark followed by flow cytometric analysis. Experiments were performed in triplicates. SD was less than 10%.