THE PROLIFERATIVE RESPONSIVENESS OF MESANGIAL CELLS TO POSTNEPHRECTOMY SERUM DECLINES PROGRESSIVELY WITH TIME ELAPSING AFTER CONTRALATERAL NEPHRECTOMY

Postnephrectomy serum has been proved to enhance proliferation of mesa ngial cells in culture. Studies in offspring to uninephrectomized (UNx ) mothers indicate that it remains active for a long period following UNx. On the other hand, postnephrectomy renal compensatory growth in v ivo is known to be completed within a short period. In this study we a ssessed the proliferative responses of mesangial cells from single kid neys of rats which were cultured 48 h or 4 months following contralate ral nephrectomy. The proliferative stimulus was provided by different postnephrectomy sera. Proliferation of both experimental cell populati ons was significantly greater than that of controls. Moreover, the pro liferation rate of early postcontralateral nephrectomy mesangial cells was greater than those harvested 4 months after nephrectomy. We, ther efore, propose that the early in vivo completion of single kidney comp ensatory hypertrophy, at least in part, is due to progressive blunting of renal cell responsiveness to the mitotic stimulus of the animal's serum.