Chronic activation of AMP-activated protein kinase prevents 20-hydroxyeicosatetraenoic acid-induced endothelial dysfunction

1. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a potent vasoconstrictor involved in vascular dysfunction and blood pressure regulation. Studies have revealed strong associations between 20-HETE and endothelial dysfunction; however, the signalling mechanisms are largely unknown. Therefore, the aim of the present study was to investigate the effect of 20-HETE on the association between endothelial nitric oxide synthase (eNOS) and heat shock protein 90 (Hsp90). 2. In mouse aortic rings, 20-HETE significantly enhanced the constriction to phenylephrine and inhibited the relaxation to acetylcholine (P=0.05 vs control rings). In mice with chronic AMP-activated protein kinase (AMPK) activation, this protected against the negative effects of 20-HETE (P<0.05). Immunoprecipitation of eNOS in human umbilical vein endothelial cells treated with 20-HETE revealed a decrease in basal and vascular endothelial growth factor-stimulated Hsp90 association with eNOS (P<0.05). Pretreatment of cells with 5'-aminoimidazole-4-carboxyamide-ribonucleoside (AICAR; a chronic activator of AMPK) prevented the loss of Hsp90 association with eNOS following 20-HETE treatment. Treatment with 20-HETE for 24 h induced an increase in eNOS phosphorylation that was not seen following acute treatment (30 min). The increased eNOS phosphorylation was accompanied by transient changes in Akt phosphorylation. 3. In conclusion, 20-HETE impairs eNOS-Hsp90 association, which can be reversed by chronic activation of AMPK. This provides a mechanism for reduced nitric oxide bioactivity and endothelial dysfunction in diseases with elevated 20-HETE levels, such as hypertension.