Discrepant effects of vasoconstrictors on the growth of early passaged cultured rat mesangial cells

Summary: Mesangial cell growth stimulation by endothelin (ET) and arginine vasopressin (AVP) has been reported, but only in studies using late (3 times) pasaged cells. In the present study, we examined the effects of ET, AVP and platelet activating factor (PAF) on the proliferation of early (<3 times) passaged cultured rat mesangial cells which maintained their original characteristics. Cell growth was estimated by [3H]-thymidine incorporation into DNA and by counting cell nuclei. After 48 h preincubation in minimal essential medium containing 0.5% fetal calf serum, ET-1 (1-100 nmol/L), AVP (100 pmol/L-1 μmol/L) or PAF (1–100 nmol/L) was added to the incubation medium. In contrast to studies using late passaged cells, ET-1 attenuated and AVP did not increase thymidine uptake (ET-1: 18.4% inhibition at 10 nmol/L) or cell counts in early passaged cells, while the growth stimulatory effects of these agents were reproduced in late passaged cells. Platelet activating factor showed definite stimulation of cell growth in both early and late passaged cells in a dose-dependent manner. These data strongly suggest that ET-1 attenuates, and AVP does not stimulate, the cell growth of original mesangial cells. the PAF-induced cell growth seems to be the constant feature of mesangial cells in vivo.