Coronary heart disease is the single leading cause of death in the United States. Reperfusion of the ischemic heart remains the best approach to limit necrosis and salvage the ischemic organ. It is now recognized, however, that the act of flow restoration causes additional organ damage, known as """"""""Reperfusion Injury"""""""". It appears that the reintroduction of blood to the ischemic heart promotes the generation and release of toxins, such as oxygen radicals, which exacerbate the ischemic damage. The heart muscle and coronary circulation are particularly vulnerable to reperfusion injury, yet little is known about the role of the coronary microcirculation in this process. to effectively combat Reperfusion Injury, we must know how, when and where it happens. In this project we will investigate the pathobiology of myocardial ischemia-reperfusion (I/R) injury with particular regard to blood-coronary microvascular interactions. We will focus on the first moments of reperfusion and the participation of blood leukocytes in microvascular dysfunction. We will observe directly where and when leukocytes accumulate in the coronary microcirculation and determine the hemodynamic consequences of white cell trapping. We will investigate the properties of leukocytes that promote retention and the role of other blood components, such as platelets and complement in modulating leukostasis. We will determine if limiting leukostasis using specific pharmacologic blockers improves microvascular function. the findings from the microcirculation studies will be applied to ventricular function efficacy studies aimed to limit Reperfusion Injury. In the cardioplegia studies, we will determine if, during elective ischemia, crystalloid cardioplegia damages the coronary endothelium and enhances leukostasis during warm reperfusion. We will test the hypothesis that cardioplegia solutions, designed to preserve microvascular integrity and limit leukostasis will improve the recovery of cardiac pump function following elective ischemia. The results from the cardioplegia microcirculation experiments will be applied to efficacy studies aimed to protect the heart and improve recovery from elective ischemia. The lessons learned from these heart studies can be applied to any organ subjected to a severe reduction in blood flow.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL049230-02
Application #
2225344
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Project Start
1993-09-01
Project End
1996-08-31
Budget Start
1994-09-01
Budget End
1995-08-31
Support Year
2
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Arizona
Department
Surgery
Type
Schools of Medicine
DUNS #
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Ritter, L S; Copeland, J G; McDonagh, P F (1998) Fucoidin reduces coronary microvascular leukocyte accumulation early in reperfusion. Ann Thorac Surg 66:2063-71;discussion 2072
Ritter, L S; McDonagh, P F (1997) Low-flow reperfusion after myocardial ischemia enhances leukocyte accumulation in coronary microcirculation. Am J Physiol 273:H1154-65
McDonagh, P F; Wilson, D S; Iwamura, H et al. (1996) CD18 antibody treatment limits early myocardial reperfusion injury after initial leukocyte deposition. J Surg Res 64:139-49
Ritter, L S; Wilson, D S; Williams, S K et al. (1996) Pentoxifylline reduces leukocyte retention in the coronary microcirculation early in reperfusion following ischemia. Int J Microcirc Clin Exp 16:170-9
Ritter, L S; Wilson, D S; Williams, S K et al. (1995) Early in reperfusion following myocardial ischemia, leukocyte activation is necessary for venular adhesion but not capillary retention. Microcirculation 2:315-27
Manciet, L H; Fox, K A; Copeland, J G et al. (1995) Left ventricular function after extended hypothermic preservation of the heart is dependent on functional coronary capillarity. Circulation 92:II372-80
McDonagh, P F; Reynolds, J M (1994) Brief perfusion with diluted whole blood after global myocardial ischaemia increases reperfusion injury. Cardiovasc Res 28:1157-65
McDonagh, P F; Rauzzino, M J (1993) Stimulated leukocyte adhesion in coronary microcirculation is reduced by a calcium antagonist. Am J Physiol 265:H476-83