ATTACHMENT OF ADULT-RAT CARDIOMYOCYTES (ARC) ON LAMININ AND 2 LAMININFRAGMENTS

Adult rat cardiomyocytes (ARC) were cultivated on five different subst rates: gelatin, fibronectin, laminin-nidogen complex (laminin), the E8 laminin fragment, and the E1 laminin fragment. Comparative cell attac hment assays have shown that ARC prefer adhesion to Eg laminin fragmen t and laminin. It were shown by video time-lapse (VTL) studies that, d uring the redifferentiation process of ARC in culture, the morphology of ARC grown on laminin, fibronectin, and gelatin is indistinguishable , whereas the size of ARC grown on the E8 fragment is larger, and when grown on the E1 fragment definitely smaller than ARC on the whole lam inin protein. Immunostaining for vinculin combined with reflection con trast microscopy were used to visualize the focal contacts of ARC on t hese substrates. Quantitative measurements, done with the help of a te st line system, show that the lengths of adhesion plaques/mu m(2) on g elatin, fibronectin, and laminin are about the same. On the E8 fragmen t more attachment sites/mu m(2) and on the E1 fragment fewer attachmen t sites/mu m(2) were counted than on whole laminin protein. This sugge sts that substrates influence the number of focal contacts. Correlatin g these results with the observations made in the VTL recording system , one can suggest that the length of adhesion sites/mu m(2) increases in very hat and large cells. (C) 1994 Academic Press, Inc.