Activation of protein kinase C impairs endothelium‐dependent vasorelaxation in isolated human omental resistance arteries

Abstract

Chronic diseases such as obesity and diabetes are associated with endothelial dysfunction and increased cardiovascular disease risk. Notably, protein kinase C (PKC) has been identified as a major molecular contributor to chronic disease‐associated microvascular impairments. However, the molecular mechanisms by which PKC activation causes microvascular endothelial dysfunction are not fully understood. Herein, we tested the hypothesis that PKC activation impairs microvascular vasorelaxation through an endothelial nitric oxide synthase (eNOS)‐dependent mechanism in human isolated resistance arteries and cultured endothelial cells. Accordingly, resistance arteries were isolated from the omentum of 32 patients (52±3 years of age, 43.3±1.7 BMI, 76% women) that underwent abdominal surgery and analyzed for vasomotor function ex vivo using wire myography. We found that pharmacological inhibition of PKC (ruboxistaurin, 1μM) for 30 minutes enhanced endothelium‐dependent vasorelaxation in response to bradykinin relative to untreated arteries (p<0.05). This effect of ruboxistaurin was abrogated by NOS inhibition (L‐NAME, 300μM), suggesting that improved endothelium‐dependent relaxation with PKC antagonism is nitric oxide‐dependent (p<0.05). Next, we found that treatment with the PKC activator, phorbol 12‐myristate 13‐acetate (PMA, 0.5μM), for 30 minutes impaired endothelium‐dependent and ‐independent vasorelaxation, which was abolished with concomitant incubation of ruboxistaurin (p<0.05). Furthermore, we found that PMA treatment reduced Akt and eNOS activation in cultured endothelial cells (HUVEC; p<0.05). In conclusion, these findings suggest that in isolated human abdominal adipose tissue resistance arteries, PKC activation impairs microvascular endothelial function likely through an eNOS‐dependent mechanism. Follow‐up experiments are ongoing to determine the involvement of specific PKC isoforms and upstream molecular regulators contributing to PKC‐mediated impairments in endothelial function.Support or Funding InformationResearch support: National Institutes of Health grants: R01 HL137769 (JP), R01 HL088105 (LM‐L).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.