Objectives: We tested whether nitric oxide scavenging with a ruthenium-based compound (AMD6221) would improve hemodynamics and alter nitric oxide synthase and matrix metalloproteinase activities in a canine model of cardiopulmonary bypass.
Methods: Dogs were randomized to either cardiopulmonary bypass (n = 12) or control (n = 12) groups. They were further randomized to receive a continuous infusion of AMD6221 or placebo. Cardiopulmonary bypass was maintained for 90 minutes, and then, 4 hours later, dogs were killed. Cardiac, lung, and brain sections were snap frozen in liquid nitrogen for determination of nitric oxide synthase, matrix metalloproteinase 2, and matrix metalloproteinase 9 activities.
Results: After cardiopulmonary bypass, 3 of 6 placebo-treated (cardiopulmonary bypass-placebo) and 0 of 6 AMD6221-treated (cardiopulmonary bypass-6221) animals required phenylephrine infusion to maintain a predetermined blood pressure (P <.05). Total fluid administration was lower in the cardiopulmonary bypass-6221 group compared with that in the cardiopulmonary bypass-placebo group (983 +/- 134 vs 1617 +/- 254 mL, respectively; P <.005). After cardiopulmonary bypass, matrix metalloproteinase 2 and matrix metalloproteinase 9 activities in the lung, left ventricle, and left atrium were decreased in the cardiopulmonary bypass-6221 group compared with that in the cardiopulmonary bypass-placebo group (P <.05). Ca(2+)-independent nitric oxide synthase activity and matrix metalloproteinase 2 activity in the brain were also lower (P <.05) in the cardiopulmonary bypass-SCV group. Finally, neutrophil expression of CD18, an adhesion complex, was lower at 4 hours after cardiopulmonary bypass in the cardiopulmonary bypass-6221 group compared with that in the cardiopulmonary bypass-placebo group (38 +/- 27 vs 81 +/- 11; P <.05).
Conclusions: We found that (1) infusion of an nitric oxide scavenger, AMD6221, was associated with improved predefined hemodynamics; (2) cardiopulmonary bypass increased activities of Ca(2+)-independent nitric oxide synthase and matrix metalloproteinases in multiple organs; and (3) AMD6221 could ameliorate the increased generation of nitric oxide and increased matrix metalloproteinase activities.