Effect of heparin-binding growth factors on monovalent cation transport in Balb/C 3T3 cells

The changes in monovalent cation fluxes induced by class 1 and class 2 heparin-binding growth factors purified from bovine brain were studied in confluent quiescent Balb/C 3T3 cells. Both classes of HBGF's rapidly stimulate the activity of the Na+-K+ pump in a concentration-dependent manner that parallels their mitogenic activity. This effect requires the presence of external Na+ and is abolished by 1 mM amiloride. As with other growth factors, HBGF's increase the activity of the Na+-K+ pump by increasing Na+ influx into the cells via the amiloride-sensitive Na+-H+ exchange. These results indicate that rapid activation of cation transport is an early cellular response that follows binding of HBGF's to specific receptors on the surface of target cells.