Interactions of Multiplication-Stimulating Activity with Bovine Endothelium: Comparative Studies in Primary, Passaged, and Cloned Cultures from the Pulmonary and Systemic Circulations*

Endothelial cells were prepared from adult bovine pulmonary and systemic vessels and maintained as primary cultures, passaged cultures, and cloned cell strains. All cultures were shown to contain endothelial cells on the basis of several endothelial-specific and endothelial-associated traits. Both primary and passaged cells demonstrated specific receptors for the insulin-like growth factor, multiplication-stimulating activity (MSA). [125I]Iodo-MSA binding was greatest in cells derived from aortas, least in pulmonary venous cells, and intermediate in pulmonary arterial cells. When compared to MSA receptors on primary endothelial cell cultures derived from human umbilical veins or arteries, the bovine cells bound 4-10 times more MSA per cell. In all bovine cells, insulin competed weakly or not at all with [125I]iodo-MSA binding. The presence of MSA receptors on primary and passaged cells from five different vascular sources (three bovine and two human) suggests that receptors for the insulin-like growth factors may be an intrinsic component of the vascular endothelium.