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 (1-100Pa), and intracellular and extracellular fluorescence was quantified via fluorescence microscopy at baseline (0min) and discrete time-points (1-30min). RESULTS: Intracellular RBC-derived NO fluorescence was significantly increased (p<0.05) following shear stress exposure when compared to baseline at: i) 1min-100Pa; ii) 5min-1, 5Pa; iii) 15min-1, 5, 35Pa; iv) 30min-35Pa. Extracellular RBC-derived NO fluorescence was significantly increased (p<0.05) following shear stress exposure when compared to baseline at: i) 5min - 100Pa; ii) 15min-100Pa; iii) 30min-40, 100Pa. 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).
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