Capsaicin inhibits calmodulin-mediated oxidative burst in rat macrophages |
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Authors: | G. Savitha Shoba Panchanathan Bharathi P. Salimath |
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Affiliation: | Department of Biochemistry, University of Mysore, Manasagangothri, Mysore 570 006, India |
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Abstract: | In this study we seek to elucidate the interaction of capsaicin with the calmodulin mediated signal pathways in macrophages, by comparing its action on macrophage functions with a known calmodulin antagonist, fluphenazine. Kinetics of capsaicin uptake by macrophages (103 cells) revealed that a maximum of 200 μM capsaicin was taken up within 10 min. Ca2+ ionophore triggered generation of superoxide anion and hydrogen peroxide by macrophages was inhibited in a dose-dependent manner by fluphenazine (IC50, 20 μM and 12 μM, respectively) and also by capsaicin (IC50, 30 μM and 9 μM, respectively), suggesting an involvement of calmodulin in the regulation of NADPH oxidase. In vitro both fluphenazine and capsaicin inhibited Ca2+-Mg2+ ATPase and cAMP-phosphodiesterase from macrophages and this inhibition was reversed by exogenous addition of calmodulin. Fluorescence studies revealed a direct Ca2+ dependent interaction of capsaicin with calmodulin. From these results we suggest that capsaicin acts via calmodulin to inhibit stimulus-induced macrophage oxidative burst and also that calmodulin regulates the oxidative burst in macrophages. |
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Keywords: | Macrophages oxidative burst calmodulin capsaicin signal transduction |
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