EFFECT OF OUABAIN AND HYPOTHALAMIC, HYPOPHYSARY INHIBITORY FACTOR ON RAT MESANGIAL CELL-PROLIFERATION

The mitogenic effect of a low-molecular-weight, Na+,K+-ATPase inhibito ry factor isolated from bovine hypothalamus and hypophysis (hypothalam ic hypophysary inhibitory factor, HHIF) and ouabain on cultured rat me sangial cells was examined. Ouabain induced a potent stimulation of th e [H-3]thymidine incorporation to DNA, ranging from threefold for a do se of 10(-7) M to seven times for 10(-5) M. The amount of proteins per well also increased in a dose-dependent way, which was already signif icant from basal values for the lower dose used. HHIF also induced a d ose-dependent stimulation of [H-3]thymidine incorporation into DNA, ra nging from 1.7 times for a concentration of 0.02 U/ml to 4.5 times for the concentration of 2 U/ml. The amount of protein per well also incr eased with HHIF, but the increase was significant only for the higher dose used. These data allow us to conclude that HHIF could play a role in the vascular hypertrophy that is associated with the pathogenesis of hypertension.