Pretreatment with eicosapentaenoic acid prevented hypoxia/reoxygenation-induced abnormality in endothelial gap junctional intercellular communicationthrough inhibiting the tyrosine kinase activity

Eicosapentaenoic acid (EPA) may protect against atherosclerotic disease, an d modulation of endothelium function is one possible mechanism. Hypoxia/reo xygenation (H/R) is a potential risk factor for the pathogenesis of atheros clerosis, and it causes endothelial dysfunction. To evaluate whether EPA ma y improve the endothelial dysfunction under the condition of H/R, we examin ed endothelial gap junctional intercellular communication (GJIC), which is said to be important for the endothelium to maintain its normal function. T he results indicate that H/R induced a temporal reduction in GJIC after 2 h of reoxygenation in cultured human umbilical vein endothelial cells (HUVEC ). This reduction in GJIC was not observed in cells pretreated with 3 mu g/ ml EPA for 2 days. The results of immunofluorescence show that 2 h reoxygen ation caused an increased production of tyrosine-phosphorylated proteins, w hich was inhibited by EPA pretreatment. Immunoprecipitation demonstrated th at tyrosine residues of connexin 43 (Cx43), an important gap junctional pro tein in HUVEC, were phosphorylated by H/R. However, pretreatment with EPA s ignificantly suppressed this increased phosphorylation. The protective effe ct of EPA on the reduction in GJIC was also observed in cells treated with 1.5 mM vanadate, a tyrosine phosphatase inhibitor. These data suggest that EPA may ameliorate the H/R-induced GJIC abnormality via inhibition of the t yrosine kinase activation.