Effect of serum renotropin on rat glomerular mesangial cell growth in vitro.

In vitro study of rat glomerular mesangial cell growth was carried out to investigate the pattern of serum renotropic stimulation in 5/6 nephrectomized (5/6NT) rats. Incorporation rates of 3H-TdR, 3H-UR and 3H-Leu into mesangial cells were used as parameters to measure serum renotropic stimulation. Renotropin activity increased immediately after 5/6NT, reaching peak at 48 h, and was succeeded by a rapid decline at 96 h postoperatively. A second rise occurred on the 7th day, followed by gradual decrement. It seemed evident that the serum obtained 48 h after 5/6NT surgery was capable of stimulating the uptake of 3H-TdR, 3H-UR and 3H-Leu by the mesangial cells (MCs). It may be concluded that renotropin promotes DNA, RNA and protein synthesis of MCs. The prolonged and constant effect of serum renotropin on MCs might be one of the important mechanisms in progressive sclerosis of the remaining kidney after subtotal nephrectomy.