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More Co2 = less brains?

Jeroen Schaap Schaap at rullf2.medfac.leidenuniv.nl
Thu Feb 13 11:53:22 EST 1997

In article <32FDFFE4.4E9A at osprey.unf.edu>,
   jander at OSPREY.UNF.EDU ("John E. Anderson") wrote:
:Jason C. Doss wrote:
:> "Ronald Blue" <rcb5 at MSN.COM> wrote in article
:> <UPMAIL07.199702081833380330 at msn.com>...
:> >
:> The actual percentage of CO2 in the atmosphere is way less than one
:> percent, whereas the percentage of O2 is greater than 20.  Therefore, other
:> more serious environmental problems will come to bear before CO2 will
:> "crowd out" atmospheric O2.
:> However, that is not to say that too much CO2 is not a big deal.  Excess
:> CO2 in the blood will acidify the blood, which will mess up the ionic
:> equilibrium of the body's cells (particularly potassium), including neurons
:> in the brain.  The deranged equilibrium probably does cause cognitive
:> defects, if mild.  However,  the condition of having too much CO2 in the
:> blood, or hypercapnia (or hypercarbia) will lead to unconsciousness if
:> severe.

Higher %CO2 in atmosphere will acidify blood only when atmospheric %CO2 will 
influence %CO2 in blood. But, seems unlikely to happen, %CO2 being determined by 
 production of CO2 in body! Lungs are important in clearing blood-CO2, not in 
taking it. At least, this holds for appr. normal atm. %C02, say .05%. Tenfold 
increase of  CO2 would NOT seriously effect bl %CO2 NOR atm %O2.  

:> By the way, CO or carbon monoxide is NOT a neurotransmitter.  In fact, it
:> is a toxin that outcompetes oxygen for binding sites on hemoglobin, thus
:> starving the body of oxygen.  You may be thinking of NO, or nitric oxide,
:> which does have intercellular signalling functions.
:CO *has* been proposed to be a neurotransmitter.  I think there was a
:PNAS commentary article by Edelman and Gally several years ago which

Aha, how many substances have NOT been proposed to be a neurotransmitter? That's 
a minority nowadays, i believe. If you ask me again, how many substances have 
positvely been proven to BE neurotransmitters, that's only a very very few. 'Can 
count'm with one hand. ;)

Anyway, ya fellows have a nice discussion. If there is a negative correlation in 
brain mass and %Co2, is there a cause-effect relation?



A man conducting a gee-whizz science show with fifty thousand dollars' worth of
Frankenstein equipment is not doing anything scientific if he knows beforehand
what the results of his efforts are going to be. A motorcycle mechanic, on the
other hand, who honks the horn to see if the battery works is informally
conducting a true scientific experiment.

							Robert M. Pirsig

== J Schaap =======================================================
         Faculty of Medicine, Leiden University
phone:   (0)71-5276763
e-mail:  SCHAAP at rullf2.MedFac.LeidenUniv.nl

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