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Functional assessment of the pulmonary microcirculation during postnatal development.
Pediatric Pharmacology (New York, N.Y.)
|January 1, 1984
Summary
Pulmonary angiotensin-converting enzyme (ACE) activity increases with age in lambs and sheep. This study measured ACE kinetics to assess the pulmonary microcirculation and endothelium during development.
Area of Science:
- Pulmonary physiology
- Cardiovascular research
- Enzyme kinetics
Background:
- The lungs metabolize vasoactive substances via enzymes like angiotensin-converting enzyme (ACE).
- Pulmonary metabolic capacity reflects the health of the pulmonary microcirculation.
- ACE converts angiotensin I to angiotensin II and inactivates bradykinin.
Purpose of the Study:
- To investigate the developmental changes in pulmonary angiotensin-converting enzyme (ACE) activity.
- To assess the utility of measuring pulmonary ACE kinetics for evaluating microcirculation integrity.
Main Methods:
- Utilized a synthetic ACE substrate, 3H-benzoyl-phenylalanyl-alanyl-proline, in developing conscious lambs and adult sheep.
- Employed indicator dilution measurements and outflow curves to derive ACE kinetic parameters.
- Applied a nonlinear model for saturable pulmonary metabolic functions.
Main Results:
- Demonstrated a significant age-related increase in Vmax (maximal velocity) of pulmonary ACE.
- Observed no significant change in apparent Km (substrate concentration at half-maximal velocity) with age.
- ACE activity measurements provide insights into pulmonary microcirculation development.
Conclusions:
- Pulmonary ACE activity and Vmax increase with postnatal development in lambs and sheep.
- This method offers a biochemical tool to study pulmonary microcirculation growth and endothelial function.
- ACE kinetic measurements can assess pulmonary vascular health in various physiological and pathological conditions.