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The relationship between endothelial dysfunction and collagen accumulation in irradiated rat lung
International Journal of Radiation Oncology, Biology, Physics
|November 1, 1985
Summary
Radiation exposure to the rat lung causes dose-dependent decreases in arterial perfusion and angiotensin converting enzyme (ACE) activity, alongside increases in fibrosis. These indicators of lung damage show similar radiosensitivities, with minimal change per Gray over time.
Area of Science:
- Radiation oncology
- Pulmonary medicine
- Biomarker research
Background:
- Radiation-induced lung injury is a significant clinical concern.
- Assessing lung damage non-invasively is crucial for effective treatment and monitoring.
- Angiotensin converting enzyme (ACE) activity and hydroxyproline (HP) are potential biomarkers for endothelial function and fibrosis, respectively.
Purpose of the Study:
- To evaluate the radiosensitivity of pulmonary arterial perfusion, endothelial function (ACE activity), and interstitial fibrosis (HP concentration) in rat lungs after gamma irradiation.
- To determine if minimally invasive measurements of ACE activity in bronchoalveolar lavage (BAL) fluid or serum can predict lung damage severity.
Main Methods:
- Male rats received single doses of 60Co gamma rays to the right hemithorax.
- Pulmonary arterial perfusion scans were performed at 2 months post-irradiation.
- Lung ACE activity and HP concentration were measured at 2 and 6 months.
- ACE activity and protein in BAL fluid and serum were also analyzed.
Main Results:
- Linear dose-response relationships (r=0.92-0.99) were observed for perfusion, ACE activity, and HP concentration.
- Perfusion decreased by 2.7%/Gy, ACE activity by 3.0-4.2%/Gy, and HP concentration increased by 1.7%/Gy at 2 months.
- Response curve slopes remained similar at 6 months, but HP concentration was 50% higher.
- BAL ACE activity and protein increased with dose but lacked sensitivity for reliable prediction.
- Serum ACE activity was independent of radiation dose.
Conclusions:
- Pulmonary arterial perfusion, endothelial dysfunction, and interstitial fibrosis exhibit similar, though not identical, radiosensitivities in the rat lung.
- These in situ lung responses show less than 5% change per Gy over a 10-30 Gy dose range.
- Minimally invasive measures like BAL or serum ACE activity are not reliable predictors of radiation-induced lung damage severity.