Specific attachment of collagen to cardiac myocytes: in vivo and in vitro.

The formation and attachment of collagen to the sarcolemma of cardiac myocytes were examined in vivo in neonatal rats and hamsters and in vitro in cultures of neonatal rat myocytes. Scanning, transmission, and high-voltage electron microscopy were used to show that the collagen struts attach to specific sites on the sarcolemma just lateral to the Z band of neonatal animals. In vitro, collagen preferentially attaches to distal end of myocytes at a site where internal stress fibers also attach to the sarcolemma. Formation of the collagen struts appeared to be a multistep process involving several components of the extracellular matrix. The role of the collagen struts is involved in the distribution of force generated by muscle contraction.