PERIPHERAL AND CENTRAL VASCULAR SMOOTH-MUSCLE CELLS FROM RAT LUNG EXHIBIT DIFFERENT CYTOSKELETAL PROTEIN PROFILES BUT SIMILAR GROWTH-FACTORREQUIREMENTS

In pulmonary vascular remodelling, the lining smooth muscle cells unde rgo various forms of growth involving cellular hypertrophy and hyperpl asia. Differences in the growth pattern between central and peripheral regions suggested that cells from both should be obtained when invest igating the cellular basis for the remodelling. Accordingly, we have o btained two smooth muscle cell types in culture: a cell from the centr al pulmonary artery (CC) and a cell morphologically similar to a peric yte (PC), from the periphery of the lung. Both cell types gave positiv e immunostaining for alpha-smooth muscle isoactin. In vivo, the alpha- isoactin was immunolocalized in the extracapillary vasculature. Quanti tative two-dimensional gel electrophoresis of cell extracts showed tha t PC express more vimentin and gelsolin than CC, Despite the differenc es between PC and CC in the expression of cytoskeletal proteins, their response to growth factors was similar. Both cell types increased DNA synthesis when stimulated by exogenous PDGF-AB. This occurred in the absence of exogenous progression factors, but depended on a post-compe tence, suramin-sensitive mechanism that probably represents an autocri ne progression factor. The cells were also stimulated by IGF-1 alone, in the absence of exogenous competence factors. At an IGF-1 concentrat ion of 1 ng/ml, this response appeared specific for the IGF-1 receptor and was sensitive to pretreatment with pertussis toxin, thus implicat ing a role for a G protein. (C) 1994 Wiley-Liss, Inc.