CHAPTER XIV 



THE INTERACTION OF CARBON MONOXIDE 

 WITH REDUCED HEMOGLOBIN 



J_ HE subject of the present chapter is the reaction of carbon mon- 

 oxide with reduced haemoglobin, the parallel to that between reduced 

 haemoglobin and oxygen. It is necessary to be quite clear about the 

 reaction under discussion and not to confuse it with another — that 

 of haemoglobin with oxygen and carbon monoxide simultaneously. 

 In the language of equations we are deahng in this chapter with 



Hb + CO :;:^ HbCO 

 and not with 



HbOa + CO rt;;; HbCO + Og, 



which latter will be discussed in Chapter xv. Until quite recently 

 little attention had been paid to the interaction of carbon monoxide 

 and haemoglobin in the absence of oxygen. 



A controversy ranged at one time about the question whether 

 the number of cubic centimetres of carbon monoxide with which a 

 gram of haemoglobin could imite was, or was not, exactly the same 

 as the volume of oxygen which attached itself to a gram of the same 

 haemoglobin. This controversy has faded into the past, and now, 

 oxygen and carbon monoxide are regarded as quantitatively inter- 

 changeable; but one never ceases to wonder that two gases which 

 are so different in their properties can play so similar a role. 



It is not merely that they unite in equal quantities x^dth haemo- 

 globin. The similarity goes much further. This became evident from 

 the first serious work which was done on the dissociation cmire of 

 CO-haemoglobin, that of Douglas, J. B. S. Haldane and J. S. 

 Haldane(i). These authors pubhshed a series of curves obtained by 

 the carmine method, for the equiUbrium of blood with carbon 

 monoxide in the presence of various COg-pressures ; repeating in 

 effect for carbon monoxide the work which had been done by Bohr, 

 Hasselbalch and Krogh (2) for oxygen. 



The comparison is very instructive. In Fig. 47 Douglas, Haldane 

 and Haldane curves for various COg-pressures are given, copied 

 directly from their paper. The COg-pressures are 0, 19, 41 and 79 mm. 

 respectively. The crosses represent Bohr, Hasselbalch and Krogh 's 



