BACKGROUND:Red blood cells (RBC) are exposed to varying shear stress while traversing the circulatory system; this shear initiates RBC-derived nitric oxide (NO) production. OBJECTIVE:The current study investigated the effect of varying shear stress dose on RBC-derived NO production. METHODS:Separated RBC were prepared with the molecular probe, diamino-fluoreoscein diacetate, for fluorometric detection of NO. Prepared RBC were exposed to discrete magnitudes of shear stress (1–100 Pa), and intracellular and extracellular fluorescence was quantified via fluorescence microscopy at baseline (0 min) and discrete time-points (1–30 min). RESULTS:Intracellular RBC-derived NO fluorescence was significantly increased (p < 0.05) following shear stress exposure when compared to baseline at: i) 1 min–100 Pa; ii) 5 min–1, 5 Pa; iii) 15 min–1, 5, 35 Pa; iv) 30 min–35 Pa. Extracellular RBC-derived NO fluorescence was significantly increased (p < 0.05) following shear stress exposure when compared to baseline at: i) 5 min – 100 Pa; ii) 15 min–100 Pa; iii) 30 min–40, 100 Pa. CONCLUSIONS:These data indicate that: i) a dose-response exists for the RBC-derived production of NO via shear stress; and ii) exposure to supra-physiological shear stress allows for the leakage of RBC intracellular contents (e.g., RBC-derived NO).