Involvement of protein kinase A in the induction of arginase in murine bone marrow-derived macrophages

Arginase is induced in hone marrow-derived macrophages by agents that increase the intracellular concentrations of cAMP (Br-cAMP, prostaglandin E(2)) and, in their presence, the LPS induced NO synthesis is down regulated. Moreover, interleukin 10 which induces arginase in macrophages is able to increase the cAMP-dependent protein kinase A activity. In contrast, suppressors of NOS synthesis Like protein kinase C inhibitors and calmodulin antagonists (W7), or NO activators (A23187) have no effect on the induction of arginase by LPS. These results strongly suggest that PKA is involved in the induction of arginase and supports the hypothesis that there is a reciprocal regulation of these two enzymes that drives the macrophages towards opposite functional states.