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Shear-stress mediated nitric oxide production within red blood cells: A dose-response. 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).