ABSTRACT
The actions of neuropeptides in the lung and their presence in normal and malignant tissues have been studied by many investigators, and some, but definitely not all, the pulmonary cell-types that contain major peptidases have been identified. This chapter aims to point out the possible roles pulmonary carboxypeptidase M (CPM) can play in vasopeptide metabolism, accented by its recent localization in some lung cells. It attempts to localize CPM in the alveolar space, using immunohisto- chemistry with cryosections of the human lung and fluorescent light microscopy. CPM is anchored to the plasma membrane by a phosphatidylinositol glycan tail attached to the C-terminal end. This is the mode of membrane attachment for CPM in many tissues, in cultured distal tubular kidney cells, and in peripheral nerves. CPM may also appear in nerves in the myelin layer, in the plasma membrane of cultured vascular endothelial cells, and in bronchial epithelial cells.
