Figure 1.

Sources of NO in blood vessels. The main source of NO in blood vessels is endothelial cells that express eNOS, which is activated by different stimuli including shear stress, bradykinin (BK), VEGF, insulin and other stimuli that could increase intracellular calcium concentration. White blood cells (WBC) produced NO by the activity of eNOS and iNOS also involved in platelet inhibition. The questions whether erythrocytes (RBC) also express functionally active eNOS and whether they could produce NO which reaches platelets are still not clear.