Most studies of activities of redox enzymes are in-vitro. However, the results of these in-vitro studies do not necessarily predict hyperoxic-induced changes in the activities of redox enzymes in an intact organ such as an intact lung. This is because potential changes in key aspects of the enzyme environment in an intact lung (e.g., availability of electron donors, competing redox enzymes, tissue permeation of electron acceptors, tissue perfusion) that may influence redox enzyme kinetics are not preserved. On another hand, the complexity of the intact organ makes the studies based on organ much harder, especially quantitative evaluation of enzyme activities. Thus, one objective of our studies is to develop a lung model to estimate the activities of cell surface, cytoplasmic, and mitochondrial redox enzymes in the intact lungs quantitatively.
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