Nitric oxide generation in red blood cells induced by mechanical stress
Issue title: Selected Proceedings of the 15th Conference of the European Society for Clinical Hemorheology and Microcirculation (ESCHM), June 28–July 1, 2009, Pontresina, Switzerland
Affiliations: Department of Physiology, Akdeniz University, Antalya, Turkey | Department of Physiology and Biophysics, Keck School of Medicine, Los Angeles, CA, USA
Note: [] Corresponding author: Dr. Oguz K. Baskurt, Department of Physiology, Akdeniz University, Faculty of Medicine, Antalya, Turkey. Tel.: +90 242 249 6963; Fax: +90 242 227 4483; E-mail: baskurt@akdeniz.edu.tr
Abstract: Previous reports have demonstrated that red blood cells (RBC) have an active nitric oxide (NO) synthesizing mechanism which has properties similar to endothelial nitric oxide synthase (eNOS). This red cell NOS activity contributes to the NO export from RBC. The present study explored the influence of shear stress applied to RBC on NO concentrations of cell suspensions. RBC were exposed to shear stress by filtration through 5µm diameter pores under 10cm H2O pressure, generating a wall shear stress of ∼110Pa. NO concentration in the RBC suspensions were measured using electrochemical NO probes before and after filtration through the micropores. NO concentration was found to be significantly increased after a single passage of RBC suspensions through the micropores. The increment in NO concentration depended on the presence of calcium, being 21.8±4.4 nM with 1 mM calcium and 13.7±2.7 nM without added calcium. Including the calcium chelator EDTA completely abolished this increase. The increment of NO was also affected by the level of oxygenation, being more pronounced under hypoxic conditions. These results confirm that RBC NO generating mechanisms can be stimulated by exposing red cells to shear stress and that calcium plays a role in this stimulation.
