CHAPTER XV 



THE INTERACTION OF CARBON MONOXIDE AND 

 OXYGEN WITH HEMOGLOBIN 



JL HE precise nature of this interaction between oxygen, carbon 

 monoxide and haemoglobin is at present a matter on which no certain 

 statement can be made. The reaction has usually been treated as 

 though it were represented by the following equation: 



HbCO + 0^:^ HbOg + CO. 



There is, however (as pointed out by Hartridge and Roughton(i)), 

 another possibiUty, namely, that the so-called reaction is really a 

 series of two reactions, namely, 



(a) HbCO :;:*: Hb + CO, 

 (6) Hb+ Oa^i^HbOg. 



The evidence, so far as it goes, will now be given briefly. 



The positive evidence in favour of the reaction of haemoglobin 

 with oxygen and carbon monoxide, being two separate reactions which 

 take place successively but independently rather than being a double 

 decomposition, may be considered under two headings, firstly, as 

 regards the conversion of carboxyhaemoglobin into oxyhsemoglobin, 

 and secondly, the conversion of oxy- into carboxyhsemoglobin. 



I. On this theory the first of these would be represented as follows : 



(a) HbCO ^- CO + Hb, 

 (6) Bh + O^—- HbOa- 



Indeed, even that is only a partial picture of this conception of 

 the reaction, for the phase (a) is so much slower than the phase (6) 

 that the reduced haemoglobin and the oxygen may always be regarded 

 as being in equiUbrium, standing at attention, so to speak, and waiting 

 for a httle more Hb to be hberated; so that the velocity of the 

 reaction is entirely controlled by the velocity of phase (a). 



The evidence for the reaction : 



rather than 



(a) HbCO --►CO + Hb, 

 (6) Hb + Og^^HbOa, 



HbCO + 02—^ HbOa + CO, 



