A) S1P-induced dilation in arterioles from nonCAD patients is reduced in the presence of the nitric oxide synthase (NOS) inhibitor L-NAME (100μM, n=5, ‡p<0.01) L-NAME versus S1P alone, as well as during exposure to the NO scavenger cPTIO (100μM, n=5, ‡p<0.01) (B). C) NO increases from baseline following exposure to increasing doses of S1P (n=4) which is quenched in the presence of L-NAME (100μM, n=3). D) NO formation in response to maximal flow (20μL/min, n=8) which is significantly reduced with L-NAME (100μM, n=3, *p<0.05). E) Representative images of NO production in vessels exposed to S1P +/− L-NAME (100μM). F) Representative images of NO formation in arterioles exposed to maximal flow (20μL/min) +/− L-NAME (100μM). Data are expressed as the mean±SEM.