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Aging: a theory based on free radical and radiation chemistry (1956)
| Venue: | J Gerontol |
| Citations: | 636 - 2 self |
BibTeX
@ARTICLE{Harman56aging:a,
author = {Denham Harman and Ph. D},
title = {Aging: a theory based on free radical and radiation chemistry},
journal = {J Gerontol},
year = {1956},
pages = {298--300}
}
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Abstract
The phenomenon of growth, decline and death-aging-has been the source of consider-able speculation (1, 8, 10). This cycle seems to be a more or less direct function of the meta-bolic rate and this in turn depends on the species (animal or plant) on which are super-imposed the factors of heredity and the effects of the stresses and strains of life-which alter the metabolic activity. The universality of this phenomenon sug-gests that the reactions which cause it are basic-ally the same in all living things. Viewing this process in the light of present day free radical and radiation chemistry and of radiobiology, it seems possible that one factor in aging may be related to deleterious side attacks of free radicals (which are normally produced in the course of cellular metabolism) on cell constituents.' Irradiation of living things induces mutation, cancer, and aging (9). Inasmuch as these also arise spontaneously in nature, it is natural to inquire if the processes might not be similar. It is believed that one mechanism of irradiation effect is through liberation of OH and HO, radicals (12). There is evidence, although in-direct, that these two highly active free radicals are produced normally in living systems. In the first place, free radicals are present in living cells; this was recently demonstrated in vivo by a paramagnetic resonance absorption method (3). Further, it was shown that the concentra-tion of free radicals increased with increasing metabolic activity in conformity with the postu-lates set forth some years ago that free radicals were involved in biologic oxidation-reduction reactions (11, 13). Are some of these free radi-cals OH and/or HO or radicals of a similar high order of reactivity, and where might they arise in the cell? The most likely source of OH and HO, radi-cals, at least in the animal cell, would be the interaction of the respiratory enzymes involved
Keyphrases
radiation chemistry free radical metabolic activity living thing cellular metabolism cell constituent living cell active free radical similar high order animal cell biologic oxidation-reduction reaction free radi-cals oh direct function meta-bolic rate present day free radical paramagnetic resonance absorption method deleterious side attack first place life-which alter likely source turn depends irradiation effect consider-able speculation thing induces mutation
