Peptides, endothelium, and pulmonary vascular reactivity

The lung contains a number of active peptides that can influence endothelial and smooth muscle function. At least two of these peptides are metabolized by endothelium, and endothelium is required for the vasodilator action of several peptides. A vasodilator peptide, VIP, may be the transmitter of the nonadrenergic, noncholinergic system, the major component of neurogenic relaxation of pulmonary vessels.