Re: [Paddlewise] cold hand adaption

Philip Torrens wrote:

> [snip] I thought I'd read somewhere that studies with
> Arctic fishermen had suggested there was actually a process of
> neovascularization (spelling?), that is the individuals actually grew
> additional blood vessels in their hands which allowed them to shunt greater
> quantities of warm blood into the extremities.

Maybe, but not needed to explain the effect.  See below.

> Sounds plausible to this layman - our muscles, red blood cell count, resting
> heart rate and so on certainly respond to exercise, exposure to altitude,
> etc. On the other hand, I suppose it could be a desperate rear-guard action
> by the last of the LaMarckist evolutionists, surrounded by Darwinists.
> Any doctors or scientists on the list care to comment on the possibility of
> this "change in the phenotype?

Far more likely is that the process of normal vasoconstriction in response to
cold water immersion has been modified -- so that vessels which would have
previously closed down get "reprogrammed" to stay open.  Reason I support that
explanation is the 6-week time for filletters (see my previous post):  probably
too short a time to generate a lot of vascularization (micro or macro).

I've noticed this acclimatisation effect in me when I used to XC-ski
regularly.  Lots greater tolerance of cold on my hands at the end of the
season.

-- 
Dave Kruger
Astoria, OR
not an M.D.
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