Q: Sleepy leg

[Anthonie Muller]

On Tue, 28 Jan 1997, Sven Haul wrote:

> >>Anthonie Muller <awjm at holyrood.ed.ac.uk> wrote:
> 
> >>My explanation it that lack of oxygen causes a decrease of 
> >>ATP, which in 
> >>turn makes it impossible to keep up the nerve membrane 
> >>potential,
> >>leading to an action potential which makes you feel the 
> >>local absence of
> >>oxygen.
> 
> This seems unlikely to mee. The cell tries to keep up the 
> membrane potential as long as possible. So if the ATP 
> shortage is prominent enough to cause a drop of membrane 
> potential by about 30 mV other damages should have occured 
> before, and should be noticeable afterwards.
> 
> regards,
> 	Sven
> 
> --
> Sven E. Haul                             Heinrich-Heine-University
> Institute of Neurophysiology             Duesseldorf, Germany
> http://www.uni-duesseldorf.de/WWW/MedFak/Neurophysiologie/haul.htm
> 
> 

Hi Sven

Maybe it is nonsense to get involved in a subject where I know little
about; maybe I'd better browse around in the library.

I vaguely remember having read that during a stroke the cellular damage is
caused by an influx of Ca2+ in the cytoplasm, the reason being that no ATP
is available to pump Ca; the absence of ATP is in turn caused by an
impedement of respiration by an absence of oxygen due to a restriction in
blood flow.
I imagine that something similar can happen in a sleepy leg.

The brain seems to react very fast to an absence of oxygenated blood: it
becomes black before your eyes. But I do not know about other tissue.

To return to the leg: during a decrease in ATP it would make sense to
effect a signal to the brain first, i.e., to let this have a high ATP
treshold, and to let irreversible damage occur at lower ATP levels. This
obviously would give the body time to react.

By the way: in the absence of oxygen the leg could obtain ATP from
fermentation. The resulting lactic acid might also cause a signal ...


Hoping that I am not wasting yours and everyone else's time ...

Cheers


Ton Muller
The Thermosynthesis Home Page
http://www.ed.ac.uk/~awjm