Vasoactive Intestinal Peptide (VIP) - Induced pulmonary vasodilation mediated by EDRF/NO in isolated perfused rat lungs

We studied the effects of Vasoactive Intestinal Peptide (VIP) on the pulmonary circulation in isolated perfused rat lungs. VIP caused pulmonary vasodilation in a dose-dependent manner. This effect was inhibited by pretreatment with L-Nω nitro-arginine (L-NNA), a competitive inhibitor of endothelium-derived relaxing factor (EDRF/NO), but not by meclofenamate, a cyclooxygenase inhibitor. Addition of L-arginine, a substrate of EDRF/NO, after treatment with L-NNA reversed VIP-induced pulmonary vasodilation. These results indicate that VIP causes pulmonary vasodilation, and they suggest a role for EDRF/NO in VIP-induced pulmonary vasodilation in isolated rat lungs.