Endotoxemia results in the release of cytokines that exert complex effects on the cardiovascular system. The purpose of this study was to 1) determine if interleukin 1 beta (IL1 beta) and tumor necrosis factor alpha (TNF alpha) elicit the release of endothelium-derived relaxing factor (EDRF) and nitric oxide derived from the constitutive nitric oxide synthase present in vascular endothelium, and 2) determine if these cytokines alter endotoxin-mediated decreases in EDRF bioactivity and nitric oxide production. Cultured bovine aortic endothelial cells were directly exposed to endotoxin, human recombinant TNF alpha, interleukin 1 beta, or a combination of endotoxin and cytokine for 1 h, followed by a second hour without endotoxin. Subsequently, both basal as well as agonist-stimulated (bradykinin) EDRF bioactivity and nitric oxide (NO) content of the effluent were quantitated. In additional experiments, endothelial cells were exposed acutely over a 30-min assay period to either endotoxin alone, cytokine alone, or endotoxin and cytokine. Following the 2-h incubation, endotoxin alone markedly reduced basal EDRF bioactivity and NO production (44 +/- 13% control, 66 +/- 13% control, respectively) and decreased bradykinin-stimulated EDRF bioactivity and NO production (58 +/- 5% control, 55 +/- 4% control, respectively). TNF alpha and IL1 beta did not stimulate EDRF release or NO production either acutely or after prolonged exposure, nor did they alter agonist-stimulated EDRF bioactivity and NO production. Similarly co-incubation of endotoxin with TNF alpha or IL1 beta failed to significantly alter the inhibitory effects of endotoxin on EDRF bioactivity and NO production.(ABSTRACT TRUNCATED AT 250 WORDS)