Exercise, free radicals, radon & repair
rabani at jeeves.ucsd.edu
Thu Jun 24 22:00:35 EST 1993
Subject: Re: Effect of exercise on longevity (was: Re: Transcendental Meditation slows/reverses biomarkers?)
References: <1993Jun18.195111.21776 at midway.uchicago.edu> <208j2g$o6e at uniwa.uwa.edu.au> <68730 at mimsy.umd.edu>
A couple of points:
Exercise produces free radicals. This shouldn't be too surprising to
anyone, since we know that energy utilization increases during exercise,
that initially this by way of glycogen anabolism (to glucose, released
to blood, taken up by cells) and that glucose is metabolized
(eventually) by mitochondria. Fat anabolism (later in exercise) also
occurs in mitochondria. Mitochondria, as readers of this group probably
know, pump out lots of radicals as a result of their synthesis of ATP.
Now, we know that free radicals dammage both proteins and DNA, and that
dammage of both is associated with aging. (Draw your own causal
arrows....) But it's not quite so simple, since repair of this dammage
occurs at response regulated levels.
A few years ago, a Sweedish study found that low levels of Radon
were associated with a longevity _increase_ of a few years. We know
that inhaling Radon exposes the organism to decay products that form
free radicals. Do we conclude that free radicals promote longevity?
Not exactly. The researchers speculated (if I recall) that this effect
was due to the induction of free radical scavengin systems and/or
repair mechanisms by low levels of free radicals. If this is the case,
it's easy to see how these responses, once induced, scavenge/repair
the Radon induced effects and then some, such that the steady state of
free-radical dammage is actually lower than ambient
(non-scavenge/repair) levels. Another point they made was that
satiety/appetite mechanisms may involve the monitoring of free-radical
levels, such that the Radon exposure could have resulted in lower
caloric intake. The free radicals released into the blood upon eating
are suspected by some to be the basis for the effects of CR: less
calories-->less radicals. This would explain the observations that
anti-oxidants don't have much lifespan effects on CRed rats, and that
the effects of CR and antioxidants are roughly as large.
(If anyone has followed research on that last point, please post
[as i was rereading this text, i decided to look for that ref. couldn't
find it on medline, but i did find this:
Search request: F KW RADON AND KW INCREASE
Search result: 31 citations in the Medline database
Display: SHO AB 1
1. Yamaoka K; Komoto Y; Suzuka I; Edamatsu R; Mori A.
Effects of radon inhalation on biological function--lipid peroxide level,
superoxide dismutase activity, and membrane fluidity.
Archives of Biochemistry and Biophysics, 1993 Apr, 302(1):37-41.
Abstract: We administered radon (Rn) to rabbits by inhalation and examined
changes in the lipid peroxide (TBARS) level, superoxide dismutase (SOD)
activity, and membrane fluidity in various organs to clarify the
therapeutic effects of Rn. The lipid peroxide level of the brain was
significantly decreased immediately after Rn inhalation for 90 min in both
the low concentration group (about 7-10 kBq/liter) and the high
concentration group (about 14-18 kBq/liter) as compared with that in the
control group. It further decreased in the low concentration group but
slightly recovered in the high concentration group 2 h after inhalation.
The lipid peroxide level of the lung showed no change immediately after
inhalation but decreased significantly in both groups 2 h after inhalation.
With regard to SOD activity in the brain and lung, only that in the brain
showed significant increase in the high concentration group immediately
after inhalation; no other change was observed. Membrane fluidity,
especially the fluidity of membrane protein, was significantly increased in
the brains of both groups immediately after inhalation, and that 2 h after
inhalation in the lung was significantly increased in both groups. These
findings suggest that the inhalation of Rn at Rn springs contributes to the
prevention of brain disorders related to peroxidation reactions by
promoting these physiologic changes.
It is, of course, worth pointing out that inhaling radon is still not
a great idea, since it does cause lung and other cancers. This is
the difference between simple life expectancy and quality of life
Another study, before World War II, found that rats exposed to low
levels of radiation also lived longer. This was refered to as the
hormetic effect. If I remember correctly, these rats also displayed
reduced ad libitum appetite. This (if memory serves) was the impetus
to look at the effects of CR on longevity.
Whatever the effects of exercise on lifespan (can anyone produce
numbers?) we do know that it is nonetheless good for you, in particular
reducing heart attacks and strokes, keeping body-fat down and
increasing blood-flow to the brain (lack of oxygen to the brain may
be an important component in Alzheimers...so if you want to live
long....) The obvious solution for anyone concerned about any potential
effects of exercise should load up on anti-oxidants (good for you
anyway) and just do it. Unless of course this is just a rationalization
to not exercise, in which case you need to find a new one
(Also, on the lifespan bit, were incidental effects, like being hit
by cars while jogging, or for that matter, sucking up exhaust fumes
while jogging, taken into account??? The latter might not be trivial,
since [we are told] living in LA is the equivalent of smoking two packs
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