Selective phosphodiesterase-5 inhibition reduces neointimal hyperplasia in rat carotid arteries after surgical endarterectomy
Received 23 July 2008; received in revised form 16 September 2008; accepted 13 October 2008. published online 11 February 2009.
Objective
Long-term results of surgical vessel reconstruction are compromised by restenosis caused by neointimal hyperplasia. Recent studies suggest that reduced cyclic guanosine monophosphate signaling is associated with neointima formation. In a rat model of endarterectomy, we investigated the effect of pharmacologic inhibition of cyclic guanosine monophosphate degradation on neointima formation by using the selective phosphodiesterase-5 inhibitor vardenafil.
Methods
Carotid endarterectomy was performed in male Sprague–Dawley rats by means of incision of the right common carotid artery with removal of intima. Four groups were studied: unoperated control rats (n = 4), sham-operated rats (n = 9), control rats with endarterectomy (n = 9), or endarterectomized rats treated with vardenafil (10 mg/kg/day) postoperatively (n = 9). After 3 weeks, vessel compartment areas were measured by means of conventional microscopy with hematoxylin and eosin staining. Immunohistochemical analysis was performed to confirm neointima formation and the local cyclic guanosine monophosphate content. Plasma levels of cyclic guanosine monophosphate were determined by means of enzyme immunoassay. Student's t test was used for statistical evaluation.
Results
Immunohistochemical analysis demonstrated intensive staining for transforming growth factor β1 and α-smooth muscle actin in the control neointima. Vardenafil significantly reduced the stenosis grade (24.64% ± 7.46% vs 54.12% ± 10.30% in the control group, P < .05) and expression of transforming growth factor β1, as well as α-smooth muscle actin, in the neointima. The immunohistochemical score for cyclic guanosine monophosphate was higher in the treated neointima (4.80 ± 0.76 vs 2.84 ± 0.40 in the control group, P < .05), and increased plasma cyclic guanosine monophosphate levels were found by means of enzyme immunoassay as well (84.65 ± 12.77 pmol/mL vs 43.50 ± 3.30 pmol/mL in the control group, P < .05).
Conclusions
Treatment with vardenafil can be considered a new possibility to prevent neointimal hyperplasia after endarterectomy.
Address for reprints: Kristóf Hirschberg, MD, Experimental Laboratory of Cardiac Surgery, University of Heidelberg, Im Neuenheimer Feld 326, OG 2, 69120 Heidelberg, Germany.
This work was partially supported by Bayer HealthCare, Wuppertal, Germany. Peter Sandner, PhD, is an employee of Bayer HealthCare, Wuppertal, Germany.
ABSTRACT