Protective effect of modafinil on skin flap survival in the experimental random-pattern skin flap model in rats: The role of ATP-sensitive potassium channels and nitric oxide pathway.

Background: The brain-stimulating agent modafinil acts through nitric oxide (NO) and adenosine triphosphate (ATP)-sensitive potassium (K) channels, involved in the skin flap survival (SFS). The main aim of this study was to investigate the efficacy of modafinil on SFS in rats through the involvement of NO pathway and K channels.

Methods: Using controlled experiment study design, we enrolled a sample of Wistar male rats. Different doses of modafinil (10, 25, 50, and 100 mg/kg) were injected intraperitoneally (i.p.) before the surgery. L-NAME (non-selective nitric oxide synthase [NOS] inhibitor), aminoguanidine (inducible NOS inhibitor), and 7-nitroindazole (neuronal NOS inhibitor) were administered prior to modafinil. The role of K channels was determined by coadministering glibenclamide (K channel blocker) or cromakalim (K channel opener) with modafinil. The predictor variables were administration of different doses of modafinil, and the coadministration of modafinil with L-NAME, aminoguanidine, 7-nitroindazole, glibenclamide, and cromakalim. The main outcome variables included the percentage of necrotic area (PNA) in flap tissues, histopathological results, vascular endothelial growth factor (VEGF) immunohistochemical (IHC) staining, and nitrite concentrations. Appropriate statistics were computed considering p-value ≤ 0.05 significant.

Results: Modafinil 25 mg/kg was the most effective dose (PNA: 26 [95% CI: 19-33]) vs. control (PNA: 81 [95% CI: 71-92]) (p< 0.001). All NOS inhibitors significantly reversed the protective effect of modafinil (p< 0.001). Non-effective dose of cromakalim had a synergistic effect with the sub-effective dose of modafinil (10 mg/kg), while glibenclamide reversed the effect of modafinil 25 mg/kg (p< 0.001).

Conclusions: Modafinil increases SFS mediated by NO pathway and K channels, which could therefore be a target to improve SFS.