Age-dependent changes in oxygen tension, radiation dose and sensitivity within normal and diseased coronary arteries-Part C: oxygen effect and its implications on high- and low-LET dose.
OBJECTIVE
The aim is to study the implications of the decrease in oxygen concentration in the coronary artery walls with age and atherosclerosis, particularly with regard to an associated reduction in the radiosensitivity to high-and low-linear-energy-transfer (LET) irradiation.


METHODS
In accompanying papers, the age-dependent morphology and composition for the wall layers of normal and diseased coronary arteries were developed in Part A from published data. In Part B, the oxygen concentration in the coronary artery walls was evaluated taking account the diffusion of oxygen from blood and the solubility of oxygen in tissues. In this part the oxygen effect was evaluated using published experimental data.


RESULTS
Based on simulation results from the one-dimensional diffusion model, the oxygen enhancement ratio (OER) is lower in the hypoxic vessel walls of aged and atherosclerotic arteries. Consequently the high-LET radiation damage arising from both the radon ((222)Rn) and thoron ((220)Rn) decay chains to the intimal layer of highly diseased arteries was estimated to be reduced by approximately 37% due to hypoxia. A greater reduction in radiosensitivity (51%) due to hypoxia was determined for low-LET irradiation.


CONCLUSIONS
These results imply that the oxygen effect, and other radiation biological factors, have a significant influence on radiation biological effects and risk of cardiovascular disease (CVD) to Japanese atomic bomb (A-bomb) survivors and patients receiving radiotherapy of the mediastinum.
Richardson
Richard B
RB
Radiation Biology and Health Physics Branch, Atomic Energy of Canada Limited (AECL), Chalk River, Ontario, Canada. richardr@aecl.ca
D000293:Adolescent; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001918:Brachytherapy / Q000009:adverse effects; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003324:Coronary Artery Disease / Q000378:metabolism* / Q000473:pathology; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism* / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D005720:Gamma Rays; D006331:Heart Diseases / Q000378:metabolism / Q000473:pathology; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D007223:Infant; D007231:Infant, Newborn; D018499:Linear Energy Transfer; D008297:Male; D008875:Middle Aged; D054043:Nuclear Weapons; D010100:Oxygen / Q000378:metabolism*; D011829:Radiation Dosage; D012306:Risk; D020521:Stroke / Q000378:metabolism / Q000473:pathology; D017539:Tunica Intima / Q000166:cytology / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D055815:Young Adult
D010100:Oxygen