CA2-INDEPENDENT NITRIC-OXIDE SYNTHASE ACTIVITY IN HUMAN LUNG AFTER CARDIOPULMONARY BYPASS()

Background - Because surgery involving cardiopulmonary bypass induces a systemic inflammatory response, the effect of cardiopulmonary bypass on nitric oxide (NO) generation was investigated in human lung tissue . Methods - Nitric oxide synthase (NOS) activity was measured by the c onversion of C-14-L-arginine to C-14-L-citrulline in tissue biopsy sam ples obtained before and after cardiopulmonary bypass. Results - The C a2+-independent proof NO found before cardiopulmonary bypass was extre mely low (1.5 (0.5) pmol citrulline/mg/min), but was increased after t he bypass operation (23.6 (11) pmol/mg/min). Conclusions - Ca2+-indepe ndent NOS activity was detected in human lung after cardiopulmonary by pass. This finding may provide an important insight into the pathogene sis of the tissue damage and acute phase response observed after such surgery.