EFFECT OF EXTRACELLULAR-MATRIX PROTEINS ON VASCULAR SMOOTH-MUSCLE CELL PHENOTYPE

The effect on phenotypic expression of rabbit vascular smooth muscle c ells (SMC) of the interstitial matrix proteins collagen I and fibronec tin, the basal lamina proteins collagen IV and laminin, and the serum adhesion protein vitronectin was examined in culture. Experiments were performed in foetal calf serum stripped of fibronectin and vitronecti n to eliminate their confounding effects. All the proteins promoted ad hesion to the plastic culture dish (in a concentration dependent manne r) of SMC freshly isolated from the artery wall. These cells had a hig h volume density of myofilaments (V(v)myo) in their cytoplasm. Laminin was best at maintaining SMC with a high V(v)myo (V(v)myo = 49.8%) fol lowed by collagen IV (41.7%). Cells plated on vitronectin showed the l owest V(v)myo (31.3%). The results support the concept that the SMC ba sal lamina has a role in maintaining cells in the high V(v)myo phenoty pe.