Inhibition of arginase by in alveolar macrophages: implications for the utilization of l‐arginine for nitric oxide synthesis

摘要

>The hypothesis was investigated that the nitric oxide (NO) synthase intermediate, data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(95)00039-C/asset/equation/feb2001457939500039c-math-si2.gif?v=1&s=5d0a09073951f3a0425ad27cfb36710a3715bfa1" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none"> (HOArg), is an arginase inhibitor in rabbit or rat alveolar macrophages. Exogenously applied HOArg strongly inhibited the arginase activity present in these cells (IC₅₀ ≥ 15 μM), and attenuated class="smallCaps">l-[3H]arginine transport (IC₅₀ ≥ 500 μM) in rabbit alveolar macrophages. Moreover, up to 37 μM HOArg were detected in the conditioned medium, but not in the lysate, of rat alveolar macrophages exposed to bacterial lipopolysaccharide for 18 h. HOArg may thus be a potent endogenous arginase inhibitor in these cells which increases the availability of class="smallCaps">l-arginine for NO biosynthesis.