Ghrelin effects on local renin angiotensin from pulmonary vessels

Background: Published data sustain the participation of vascular renin angiotensin system (RAS) on alteration of pulmonary vessels reactivity during the allergic airway inflammation. Ghrelin is a growth hormone-releasing peptide involved in modulation of immune function. Objective: This study aims to investigate the interaction between ghrelin and local RAS from rat pulmonary vessels during ovalbumin – induced allergic airway disease. Methods: The angiotensinogen (AGT) – induced contractions were assessed on isolated pulmonary artery and veins from ovalbumin sensitized rats receiving either saline (OSR) or ghrelin (OSG) by endotracheal instillation. Experiments were performed in the absence or the presence of losartan, D-ALA7, chymostatin and N-nitro-L-arginine methyl ester (L-NAME). Results: The angiotensinogen (AGT) contractile effects mediated by AT1 receptors were lower with at least 25% on vessels from OSG than from OSR. The D-ALA7 and LNAME significantly increases the AGT - induced contraction on OSG. The amount of nitric oxide released after stimulation with angiotensinogen (AGT) is higher on OSG and it is blocked by D-ALA7. Conclusion: Our results suggested that pulmonary delivery of ghrelin could modulate the local RAS from pulmonary vessels, probably by promoting the angiotensin 1-7 mediated effects. These data sustained the existence of another possible way for ghrelin9s beneficial effects on the lung.