Fig. 6. Regulation of mesangial cell gene expression by ET-1 requires distinct signaling pathways. Regulation of p8 expression is indistinguishable from that of hypertrophy. (A) Suppression of gene induction by specific protein kinase pathway inhibitors. Mesangial cells were pre-treated with the indicated inhibitors and then treated with ET-1 for 24 h (upper panel) or for 1 h (lower panel). Expression was detected by northern blotting, and gapdh expression was used as a loading control. (B) High glucose induces p8 expression to a degree commensurate with ET-1. ET-1 and glucose are not synergistic. Serum-starved cells were treated with high glucose (30 mM), ET-1 or both for 24 h. p8 expression was monitored by northern blotting.