Endothelin-1 stimulates vascular smooth muscle and mesangial cells to release prostaglandin E2 which attenuates the vasoconstrictor and mitogenic effects of endothelin. The role of endothelin-1 to regulate prostaglandin endoperoxide synthase (PGHS)-1 and -2 gene expression and protein synthesis was evaluated in cultured mesangial cells. Endothelin induced mRNA and protein expression for PGHS-2 but not for PGHS-1. A direct correlation was observed between the mass of immunoprecipitated PGHS protein and PGE2 synthetic enzymatic activity.