Just to make it clear – I still believe that oxidative stress contributes to aging, it’s just I do not believe it is exacerbated by higher metabolic rates (at least under normal conditions).
On Mon, Dec 22, 2014 at 2:03 PM, Rafal Smigrodzki wrote:
On Mon, Dec 22, 2014 at 9:50 AM, Robert Young wrote:
I note here:
“A higher metabolic rate and elevated oxidative stress levels have been thought of as the primary factors in the aging process”
While not everyone may agree, there is definitely a line of reasoning that supports such an idea, and at least some research to back it up (such as with giant tortoises living a long time).
It makes sense that if oxidative stress contributes to aging, reducing the rate of metabolism will lower the rate of oxidative stress.
### It would make sense only if you also believed that increased metabolic rate (i.e. specifically, increased ATP synthesis rate at complex V driven by normally functioning electron transport chain) inevitably leads to increased oxidative stress. But, in fact there is no such connection – oxidative stress is caused by damage to the ETC or by blockage of the ETC (most commonly), not by normal functioning of the ETC, and normally there is no increase in ROS production as the substrate flux through the ETC increases. In that sense the rate of living hypothesis is contradicted by available evidence – and of course, we know about many high-metabolism organisms with great longevity, so there is another strong piece of evidence against it.