The endothelium participates on the regulation of hemodynamic processes. In vascular disorders such as the ones observed in diabetes and hypertension, endothelial function is severely deteriorated. One of the substances involved in the regulation of endothelial function is bradykinin (BK), through the activation of two receptors B1KR and B2KR. While the B2KR is expressed constitutively, the B1KR is absent in physiological conditions but it is induced by inflammation and injury. We are interested in dillucidating the signalling cascade activated by BK in pathological conditions such as diabetes where both receptors have been documented. To approach this question, we determined the effects of high glucose (25 mM) on BK-activated signalling in endothelial cells in culture. We used the human cell line EAhy-926 cultured in normal (5 mM) or high glucose for 24 h prior to the stimulation with BK. Experiments were done in quadruplicate and expressed as mean±SEM. Values were analysed by the non parametric method of Kruskal-Wallis, and were considered different if p<0.05. BK induced an increase in Extracellular Regulated Kinases 1 and 2 (ERK1/2) phosphorylation that was maximal at 5 min (29±18% over control; n=4) whereas ERK1/2 phosphorylation was decreased (48±9% of control; n=4) at 15 min when cells were cultured in high glucose. In addition, BK induced an increase in PGE₂ concentration in the supernatants (199 pg/mg in control versus 517 pg/mg in BK stimulated; n=4) measured by ELISA, after 24 h of incubation in normal glucose but caused a decrease in the concentration of this prostaglandin (451 pg/mg in control versus 281 pg/mg in BK-stimulated; n=4) when cells were cultured in high glucose. In agreement with this observation, BK induced an increase in COX-2 protein expression determined by Western-blot that was maximal at 6 h in normal glucose, whereas it induced a decrease in COX-2 expression when cells were cultured in high glucose (n=4). High glucose induced an increase in the B1KR protein that was maximal at 12 h (200±13% over control; n=4). In addition, the B1 agonist des-Arg⁹-BK, in the presence of Icatiban (a B2KR specific antagonist), induced an increase in nitric oxide (NO) release measured by the method of Greiss that was maximal at 15 min (2.5-fold over control; n=4) in high glucose. This effect was not observed when cells were cultured in normal glucose. In conclusion we have observed that high glucose increases the expression of the B1KR and modifies the effects of BK on ERK1/2 activation, PGE₂ and NO generation and these results suggest that high glucose may alter endothelial function by shifting BK signalling from the B2KR to the B1KR pathways.