Diclofenac inhibits Kv1.3 and Kir2.1 expressions in human macrophages and affects the membrane potential and foam cell formation / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the effect of diclofenac on the expression of Kv1.3 and Kir2.1 channels in human macrophages and the membrane potential and foaming process of the macrophages.</p><p><b>METHODS</b>The effect of diclofenac on the expression of Kv1.3 and Kir2.1 channels in cultured human monocyte-derived macrophages was investigated using real-time RT-PCR and Western blotting, and its effect on the membrane potential was analyzed with optical mapping of the membrane potential with voltage-sensitive dyes. The ratio of cholesterol ester (CE) in the macrophages following intake of oxidized low-density lipoprotein (OxLDL) was analyzed by an enzymatic fluorometric method.</p><p><b>RESULTS</b>The expression of Kv1.3 and Kir2.1 channels in the macrophages were down-regulated by diclofenac (1.5 µmol/L and 15 µmol/L). Compared with those in the control group, Kv1.3 mRNA expression was reduced by over 80% and 90% (P<0.05), and Kir2.1 mRNA by over 20% and 30% (P>0.05), respectively; both their protein expression was reduced by over 10% and 60% with a dose- dependent effect (P<0.05). Diclofenac at the two doses dose-dependently reduced the surface fluorescence intensity of the macrophage, and the membrane potential was decreased by 28% and 54%, respectively (P<0.05). Incubation of the macrophages with 30 mg/L OxLDL for 60 h caused an obvious enlargement of the cell volume and deposition of numerous lipid granules in cytoplasm, resulting also in a CE/TC ratio over 50% (P<0.05). Diclofenac at 1.5 and 15 µmol/L both significantly decreased the CE/TC ratio to (23.624∓3.34)% and (13.601∓2.916)% (P<0.05), respectively, but this effect did not show a dose-response relationship (P>0.05).</p><p><b>CONCLUSION</b>Diclofenac can significant down-regulate the expression of Kv1.3 and Kir2.1 channels in human macrophages, lower their membrane potential and inhibit the process of foam cell formation.</p>