A, Incubation with the specific NSmase inhibitor GW4869 (4μM, 16-20hrs) did not affect the overall magnitude of dilation to flow compared to vehicle-treated control (n=9 and 8, respectively). B, The response to flow was inhibited in CAD vessels first incubated with GW4869 in the presence of L-NAME (100μM) compared to GW4869 alone, whereas PEG-catalase (500U) had no effect (n=5, 9, and 5, respectively). *p<0.05 vs. GW4869 at specific pressure gradients.