Radiation effects on oxidative metabolism in young and aged rat alveolar macrophages.
The effect of ionizing radiation on metabolic functions of alveolar macrophages (AM) have been well studied. However, variations associated to age have not been established yet. The aim of this work was to perform a comparative study on irradiated alveolar macrophages from young and aged rat lungs. Cell viability and occurrence of apoptosis as well as production of nitric oxide (NO), generation of superoxide anion (O2*-) and total antioxidant capacity were analyzed in vitro after exposure to gamma-irradiation with 10, 25, 50 and 75 Gy. Cell viability decreased only in the aged population at the higher doses. Morphological features of apoptosis were clearly evidenced in irradiated alveolar macrophages from aged animals although the DNA fragmentation assay for apoptosis showed no differences for either of the populations studied. NO production and total reactive antioxidant potential (TRAP) levels showed a dose-dependent modulation. Low radiation doses inhibited the production of NO and decreased TRAP levels whereas higher doses enhanced the NO production and increased the TRAP levels in both macrophage populations. Generation of O2*- was always higher in the aged population for all the doses assayed. We conclude that in vitro young alveolar macrophages exhibited higher radioresistance over the whole range of doses as compared to the aged macrophage population. Our results show that the aging process markedly affects the radioresistance of phagocytic cells. Therefore, immune defense and inflammatory response of lungs from aged patients should be considered when planning radiotherapy protocols.
Tasat
Deborah R
DR
School of Science and Technology, National University of General San Martín, Buenos Aires, Argentina. tasat@cnea.gov.ar
Mancuso
Regina
R
Evelson
Pablo
P
Polo
José M
JM
Llesuy
Susana
S
Molinari
Beatriz
B
D000367:Age Factors; D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000528:radiation effects*; D017209:Apoptosis / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D016676:Macrophages, Alveolar / Q000378:metabolism / Q000528:radiation effects*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000528:radiation effects; D010084:Oxidation-Reduction / Q000528:radiation effects; D051381:Rats; D013481:Superoxides / Q000378:metabolism / Q000528:radiation effects
D000975:Antioxidants; D013481:Superoxides; D009569:Nitric Oxide