Stroke-free survival in L/D-NAME systemically treated rats after infusion with human sickle or control RBCs. Washed human SS-RBCs or AA-RBCs (3 mL) were infused into rats systemically treated with either L-NAME or D-NAME and LDF monitored as described in the Materials and Methods and the time to stroke was measured. Stroke was defined as the time when LDF was less than 10. The probability of stroke-free survival is shown beginning from completion of the RBC infusion (time = 0 minutes) to the end of the experimental protocol (time = 30 minutes) for the four treatment groups: L-NAME +SS-RBCs (LN-SS, n = 9), L-NAME + AA-RBCs (LN-AA, n = 6), D-NAME + SS-RBCs (DN-SS, n = 5), and D-NAME + AA-RBCs (DN-AA, n = 3). Five of nine rats infused with SS-RBCs after L-NAME treatment (LN-SS) experienced a stroke within 30 minutes of the RBC infusion (*P = .0012). All rats that experienced a stroke subsequently died.