Patterns of an Angiotensin Converting Enzyme (ACE) Substrate Hydrolysis by Pulmonary Capillary Endothelium-Bound ACE in Critically Ill Patients
The pulmonary vascular endothelium participates in various important physiologic processes, such as synthesis, release and degradation of hormones and vasoactive peptides, prostaglandin synthesis, release and uptake, lipid processing, xenobiotic metabolism, and antithrombogenic-thrombolytic activities (Orfanos and Catravas, 1993). Enzymes responsible for many of these functions are located on the luminal surface of the capillaries (ectoenzymes). Due to their location, they are directly accessible to blood-borne substrates and their activities may be measured in vivo by means of indicator-dilution type techniques. Among these enzymes, angiotensin-converting enzyme (ACE) a major regulator of systemic blood pressure has been extensively studied in animals: monitoring pulmonary capillary endothelium-bound (PCEB) ACE activity in vivo under normal conditions allows estimations of the dynamically perfused capillary surface area (DPCSA; Orfanos et al., 1994), whereas under toxic conditions provides an early index of lung injury. We have initiated similar studies in man, in an effort to validate the use of the aforementioned techniques as a tool of pulmonary endothelial function assessment in the normal and injured human lung.
KeywordsLung Injury Angiotensin Convert Enzyme Pulmonary Blood Flow Angiotensin Convert Enzyme Activity Important Physiologic Process
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- Orfanos and Catravas, In: Annual of Cardiac Surgery, Yacoub & Pepper (eds.), Current Science, London, 1993, pp. 52–59.Google Scholar