A BABOON MODEL FOR HEMATOLOGIC STUDIES OF CARDIOPULMONARY BYPASS

Objective investigation of new inhibitors of blood protein or cellular systems that are activated during cardiopulmonary bypass (CPB) is imp eded by the absence of a satisfactory animal model. Because most baboo n hematologic proteins immunologically cross-react with those used for human assays, we developed a robust, reusable baboon model of CPB. Bl ood samples were obtained from adult baboons at six time intervals bef ore, during, and after 60 minutes of partial CPB at 37 degrees C with peripheral cannulas. Both membrane (n = 7) and bubble oxygenators (n = 7) were investigated. We measured platelet and white blood cell count s; platelet response to adenosine diphosphate and release of beta-thro mboglobulin; fibrinopeptide A, prothrombin fragment F-1.2, thrombin-an tithrombin complex, D-dimer, and plasmin-antiplasmin complex; activate d complement (C3b/c and C4b/c); elastase-alpha(1) proteinase inhibitor complex; and bleeding times. Adherent glycoprotein IIIa antigen in Tr iton X-100 washes of the perfusion circuit was also measured. Markers of baboon platelet, complement, and neutrophil activation and thrombos is significantly increased during CPB with bubble oxygenator systems b ut did not change appreciably in membrane oxygenator circuits. Markers of fibrinolysis, D-dimer, and plasmin-antiplasmin complex did not cha nge with either oxygenator. The baboon model of CPB, when a bubble oxy genator is used, is a robust, reusable animal model for evaluating inh ibitors of platelet, complement, and neutrophil activation and thrombo sis during and after CPB.