Inducible nitric oxide synthase (iNOS) in endotoxemia: chimeric mice reveal different cellular sources in various tissues.

The aim of these experiments was to determine the contribution of leukocyte-derived iNOS to total iNOS expression induced by lipopolysaccharide (LPS). By transferring bone marrow between iNOS+/+ and iNOS-/- mice, we created chimeric mice in which iNOS expression was limited to either circulating leukocytes (leukocyte-iNOS mice) or parenchymal cells (parenchyma-iNOS mice). Analysis of congenic markers demonstrated that >95% of thymocytes in chimeric mice were of donor origin.