BUMETANIDE AND FUROSEMIDE INHIBITED VASCULAR ENDOTHELIAL-CELL PROLIFERATION

In this study, we examined the role of the bumetanide-sensitive Na+/K/Cl cotransport in the mitogenic signal of vascular endothelial cell p roliferation. The activity of the Na+/K+/Cl- cotransport is dramatical ly decreased in quiescent subconfluent cells, as compared to subconflu ent cells growing in the presence of FGF. The Na+/K+/Cl- cotransport a ctivity of quiescent subconfluent cultures deprived of FGF decreased t o 6%, whereas that of quiescent cells grown to confluency was reduced to only 33% of the activity of subconfluent cells growing in the prese nce of FGF. The basal low activity of Na+/K+/Cl- cotransport in the qu iescent subconfluent vascular endothelial cells was dramatically stimu lated by FGF. In order to explore the role of the Na+/K+/Cl- cotranspo rt in the mitogenic signal of the endothelial cells, the effect of two specific inhibitors of the cotransport -furosemide and -bumetanide wa s tested on cell proliferation induced by FGF. Bumetanide and furosemi de inhibited synchronized cell proliferation measured by direct counti ng of cells and by DNA synthesis. Inhibition by fuorsemide and bumetan ide was reversible; removal of these compounds completely released the cells to proliferate. These results indicate that the effect of these drugs is specific and is not due to an indirect toxic effect. This st udy clearly demonstrates that the FGF-induced activation of the Na+/K/Cl- cotransport plays a role in the mitogenic signal pathway of vascu lar endothelial cells. (C) 1994 Wiley-Liss, Inc.