Perivascular adipose tissue impairs coronary endothelial function via protein kinase C‐beta dependent phosphorylation of nitric oxide synthase

Our laboratory recently demonstrated that perivascular adipose tissue significantly diminishes coronary nitric oxide production and endothelial‐dependent dilation. However, the exact mechanisms by which adipose‐derived factors impair coronary endothelial function have not been fully elucidated. Accordingly, this study was designed to delineate the cellular/molecular pathways involved in adipose‐induced coronary endothelial dysfunction. Experiments were conducted in isolated canine circumflex coronary arteries with and without perivascular adipose tissue. Adipose tissue significantly decreased coronary endothelial‐dependent vasodilation to bradykinin (1 – 30 nM) ∼ 30% and increased EC50 2.4‐fold (n = 4). This effect of adipose tissue was not observed in arteries pretreated with the general protein kinase C (PKC) inhibitor Ro 31‐8220 (1 μM, n = 7) or the PKC‐β specific inhibitor ruboxistaurin (1 μM, n = 6). Western blot analysis revealed phosphorylation of endothelial nitric oxide synthase (eNOS) at threonine‐495 in arteries with adipose tissue that was reversed by inhibition of PKC‐β with ruboxistaurin and was not present in arteries without adipose tissue (n = 4). Taken together these data indicate that perivascular adipose tissue impairs coronary endothelial nitric oxide production via a PKC‐β dependent, site‐specific phosphorylation of eNOS at threonine‐495. (Support: HL67804)