Hemoglobin and Cyanide

Doug Yanega dyanega at denr1.igis.uiuc.edu
Tue Dec 5 12:24:51 EST 1995


> In article <Bob_Hoesch.447.000FF06D at fws.gov> Bob_Hoesch at fws.gov (Bob
Hoesch) writes:
> 
> >If one is using hemoglobin as a marker for analyzing population   
> >genetics, a standard procedure is to treat the blood sample with low 
> >concentrations of cyanide prior to IEF (isoelectric focusing).  This 
> >results in the elimination of "spurious" bands, and apparently makes    
> >the resulting banding patterns amenable to genetic analysis. I've heard    
> >this procedure described as "reduction of methemoglobin" (reduction of     
> >the oxidized iron back to the reduced state), but this doesn't make sense 
> >to me in terms of the chemistry. Can someone explain what is happening in 
> >this cyanide-induced reduction in the number of hemoglobin bands?  How could 
> >cyanide reduce Fe3+ to Fe2+?  
> 
> It doesn't.  Methemoglobin forms a tight complex with CN, and ordinary Hb 
> doesn't.  Presumably this affects the absorption bands enough to eliminate 
> them as interference.  One of the treatments for HCN poisoning is to
inhale an 
> organic nitrite, which oxidizes Hb to mHb.  The CN is then tied up by the mHb 
> instead of trashing the cytochroma oxidase, which is its toxic target.

This raises a question: I've been told by a colleague that cyanide builds
up in the body tissues over time, and that after years of slight sublethal
doses, one more tiny dose can "push a person over the edge" suddenly. This
was part of his mandatory education working in an analytical chemistry lab
some 40 years ago. This seems completely at odds with my understanding of
the chemistry involved in cyanide toxicity, and I'm curious as to whether
this is at all possible - I'm a professional entomologist, and am exposed
to sublethal doses of cyanide hundreds of times a year, virtually every
time I use a killing jar. I can't believe that I'm just cranking up some
invisible physiological ratchet, and priming myself to drop dead some day
when I catch that one fatal whiff.
Thanks,
-- 
Doug Yanega                    Illinois Natural History Survey,
607 E. Peabody Dr. Champaign, IL 61820  USA    (217) 244-6817
affiliate, University of Illinois Dept. of Entomology
"There are some enterprises in which a careful disorderliness is
    the true method" - Herman Melville, Moby Dick



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