Addition of vardenafil into storage solution protects the endothelium in a hypoxia- reoxygenation model

Aims: Vascular grafts are stored often under hypotermic conditions. However, in vitro studies showed that vessels kept in physiologic saline exhibited significant loss of structurally intact endothelium. During reperfusion reactive oxygen species induce oxidative stress and DNA injury leading to endothelial dysfunction. Growing evidence suggests that elevated intracellular cGMP levels may contribute to an effective cytoprotection against oxidative stress. Methods: In organ baths, endothelium dependent and independent vasorelaxations were assessed in rings of isolated thoracic aorta obtained from Sprague-Dawley rats. Aortic segments underwent a 24h cold ischemic preservation in physiologic saline or vardenafil (10 -11 M) supplemented saline solution. Endothelial reperfusion injury was simulated by exposing the rings to hypochlorite (200µM) for 30 minutes. Histopathological examination of the aortic tissue was performed. Results: Compared with control, the saline group showed significantly attenuated endothelium-dependent maximal relaxation (R max ) to acetylcholine after hypoxia-reoxygenation, which was significantly improved by vardenafil supplementation (R max control: 98 ± 0.6% vs. saline: 48 ± 5.6% vs. vardenafil: 74.8 ± 3.5%, p < 0.05). In contrast, the endothelium-independent relaxations induced by 10 -10 -10 -5 M sodium nitroprusside did not show difference between the experimental groups. Vardenafil-treatment significantly reduced DNA-breakage as evidenced by positive TUNEL assay and increased cGMP score in the aortic wall. Conclusions: Our results support the view that impairment of the intracellular cGMP-signaling play a role in the pathogenesis of the endothelial dysfunction induced by cold storage warm reperfusion, which can effectively be reversed by pharmacological PDE-5-inhibition.