[Protein kinase C activation is required for free fatty acid-induced impairment of endothelial nitric oxide synthase].
OBJECTIVE
To observe whether the impairment of endothelial nitric oxide synthase (eNOS) activity by elevated level of free fatty acid (FFA) is associated with activation of protein kinase C (PKC).


METHODS
The cultured human umbilical vein endothelial cells were used for four groups: control group, oleic acid (OA) group (10, 50, 100, 150, 200 micromol/L), GFX group and OA+GFX group. The activity of eNOS in each group was examined, and the activity and expression of PKC were determined in both control and OA groups. The method of immunocytochemistry was performed to detect the expression of p-eNOS(1177) in control, OA (100 micromol/L), GFX and OA+GFX groups respectively.


RESULTS
Compared with control group, the eNOS activity of endothelial cells in OA group was significantly reduced in a dose-dependent manner, and the expression of p-eNOS(1177) were also impaired (0.0854 +/- 0.017 vs. 0.0134 +/- 0.023, P < 0.05). PKC transposition from endochylema to cytomembrane was observed by confocal microscopy. The PKC activity was degraded in endochylema, while enhanced in cell membrane inversely, and the gross activity of PKC increased after all. When GFX, an inhibition of PKC, was added to endothelial cells at the present of OA or not, the impaired eNOS activity were partly improved.


CONCLUSIONS
Elevated level of FFA (here is oleic acid) leading to endothelial dysfunction results from a loss of eNOS activity and its serine phosphorylation, and it may be related to activation of PKC.
Li
Chun
C
Division of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu 610041, China.
Li
Hong-liang
HL
Yu
Ye-rong
YR
Zhang
Xiang-xun
XX
D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology*; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D019301:Oleic Acid / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D014471:Umbilical Veins / Q000166:cytology
D005230:Fatty Acids, Nonesterified; D007211:Indoles; D008301:Maleimides; D019301:Oleic Acid; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D011493:Protein Kinase C; C070515:bisindolylmaleimide I