Nitric Oxide (NO) is a physiological signalling molecule produced by enzymes of the NO synthase family and plays a role in a broad range of physiological processes. We studied cell migration of primary murine aortic endothelial cells (MAECs) after treatment with specific eNOS-inhibitors (L-NAME, L- NMMA) and nitric oxide donors (NOC-18). Using in vitro migration assays, i.e. Boyden Chamber and wound healing assays we observed that addition of NO increased the migration velocity from 2.14 E-8 ± 1.91 E-8 m/s to 8.47 E-8 ± 2.76 E-8 m/s in normal culture conditions. Conversely, inhibition of eNOS completely blocked in vitro wound healing and removal of the inhibiting agents resulted in full recovery of the migration.

In order to further analyse the mechanism of NO-mediated migration we investigated membrane trafficking processes: There was a complete loss of endocytosis after inhibition of eNOS, as tested by a transferrin uptake assay. The small GTPase Cdc42/N- Wasp signal transduction pathway has previously been implicated in intracellular actin cytoskeleton rearrangements. Interestingly, blocking migration by NO-Synthase inhibitors was not accompanied with changes in Cdc42 activity.

Taken together, NO develops reversible and Cdc42-independent effects in cell migration of MAECs.