Characterization and modulation of nitric oxide synthesis by physiological electrical stimulation.

摘要

Electrotherapy for bone healing, remodeling and wound healing may bemediated by modulation of nitric oxide (NO). Using NO-specific fluorophore, we report here that application of non-invasive, physiologic electrical stimulation induces NO synthesis in human osteoblasts, and that such NO generation is comparable to that induced by estrogen treatment. For example, application of a sinusoidal 1 Hz, 2 V/cm (peak to peak) electrical stimulation (ES) increases NO-bound DAF-2 fluorescence intensity by a 2-fold within 60 min exposure by activating nitric oxide synthase (NOS). Increase in the NO level is found to depend critically on the frequency and strength of ES. Nitric oxide synthesis in response to ES is completely prevented by blocking estrogen receptors using a competitive inhibitor, suggesting that NO generation is likely initiated by activation of estrogen receptors at the cell surface. NO production in response to ES is found to be Ca2+ independent, and is mediated by the activation of iNOS, whereas estrogen activates the Ca2+ dependent eNOS isoform. Based on these findings, physiologic stimulation of electrotherapy appears to represent a potential non-invasive, non-genomic, externally applied, and novel physical technique that could he used to regulate NO-mediated bone density and facilitate bone remodeling without adverse effects associated with hormone therapy.