Arachidonic acid inhibits the production of angiotensin-converting enzyme in human primary adipocytes via a NF-κB-dependent pathway

Figures

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  Figure 1. The oil red O staining of differentiated cells photographed using a microscope (×100). Lipid droplets are stained in red.

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  Figure 2. The angiotensin-converting enzyme (ACE) mRNA level in the cell extract and ACE activity in the culture media are measured under the stimuli of palmic acid (PA, 500 µM) or arachidonic acid (AA, 50, 100, 200 µM), respectively. (A) In the presence of 500 µM PA, the mRNA expression of ACE in the fat cell extract is not affected compared with controls (P=0.183). (B) Similar results are obtained for ACE activity in the culture media treated with the same PA concentration (P=0.096). (C) In the presence of AA at different concentrations, the expression of ACE mRNA in the culture media shows a statistical difference (P=0.0013). (D) ACE activity shows a similar response under the same condition (P<0.0001). As the dosage of AA is increased, the ACE expression and activity show trends of decline (n=3). The effect of 100 µM AA on ACE expression and ACE activity are displayed in part (E) and (F), respectively (P=0.005, P<0.001). All values are expressed as mean ± SD of 3 experiments, and each experiment is conducted in triplicate.

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  Figure 3. The inhibitory effect of arachidonic acid on ACE production in human subcutaneous adipocytes was reversed by NF-ƙB inhibitor (NI) and 20-HETE inhibitor HET0016 (HET). (A) The reversal of the inhibition of angiotensin-converting enzyme (ACE) mRNA expression in the presence of 100 µM arachidonic acid (AA100) by the 5 µM NF-ƙB inhibitor BAY117082 (NI) in cultured adipocytes (n=3). (B) 10 µM 20-HETE inhibitor HET0016 (HET) competes off the inhibition of ACE mRNA expression by 100 µM AA (AA100) (n=3). (C) Reversal of the AA-induced (100 µM, AA100) inhibition of ACE activity by 10 µM HET0016 (HET) (n=3). (D) ACE activity is down-regulated when a mere 10 nM 20-HETE is added in the culture media of adipocytes. All values are expressed as mean ± SD of 3 experiments, and each experiment is conducted in triplicate.