O‐GlcNAcylation increases vascular reactivity in rat aorta

Abstract

Introduction: O‐Linked N‐acetylglucosaminylation (O‐GlcNAcylation) plays an important role in many aspects of protein function. Whereas elevated O‐GlcNAc levels contribute to diabetes related end‐organ damage, O‐GlcNAcylation is also physiologically important.Aim: Because proteins that play a role in vascular tone regulation can be O‐GlcNAcylated, we hypothesized that O‐GlcNAcylation increases vascular reactivity to contractile stimuli.Methods: Aortas from Sprague‐Dawley male rats were incubated for 24 h with vehicle, PugNAc (O‐GlcNAcase inhibitor, 100μM), azaserine (GFAT inhibitor, 20μM), high glucose (25mM) or manitol (25mM).Results: PugNAc incubation, but not azaserine, manitol or high glucose, significantly increased O‐GlcNAc‐proteins (Fig A), as determined by Western blot. PugNAc also increased phenylephrine and KCl contractions, which was not observed in the presence of L‐NAME. PugNAc decreased acetylcholine (Fig B), but not sodium nitroprusside, relaxation. Incubation with azaserine, high glucose or manitol did not change vascular reactivity. PugNAc incubation augmented e‐NOS levels, but decreased e‐NOS1177 phosphorylation.Conclusions: Vascular O‐GlcNAcylation modulates vascular reactivity, possibly due to its effects on e‐NOS expression and activity, reinforcing the idea that O‐GlcNAcylation is important in physiological conditions.Support: NIH / CAPES