Endothelin-1 (ET-1) is a potent vasoconstrictor peptide synthesized and secreted by vascular endothelial cells. Regulation of ET-1 production occurs at the level of gene transcription. We previously demonstrated a role for arachidonic acid as an intracellular mediator in the regulation of gene expression. This study investigated the role of arachidonic acid in induction of ET-1 production in endothelial cells. Challenge of bovine aortic endothelial cells (BAECs) with arachidonic acid induced a dose-and time-dependent increase in the amount of immunoreactive ET-1 in the supernatant. The maximum effect was observed at concentrations of 20 Β΅M. Release of ET-1 by arachidonic acid was preceded by induction of ET-1 gene expression. Arachidonic acid increased ET-1 gene expression by increasing transcription of the ET-1 gene. The effect of arachidonic acid was mimicked by other polyunsaturated fatty acids, whereas saturated fatty acids had no effect. Moreover, inhibitors of the lipoxygenase pathway blocked arachidonic acid-induced release of ET-1. These results suggest that arachidonic acid stimulated the production of ET-1 in BAECs by inducing ET-1 gene transcription. Arachidonic acid-induced production of ET-1 is dependent on lipoxygenase products of arachidonate metabolism.