Aspects of the Oxygenation and Oxidation 



Functions 



DAVID L. DRABKIN 



Measurements are reported and their uncertainties discussed in 

 the determination of the oxygen dissociation curve of the arterial 

 blood of man in vivo. The oxygen saturation {percentage of oxy- 

 haemoglobin of total blood pigment) is determined by direct spectro- 

 photometry, with a special cuvette of 0-007 cm depth. This container 

 avoids the inaccuracy inherent in the delivery of a specified blood 

 volume by means of pipettes, and permits the rapid measurement of 

 the undiluted, fresh blood sample unexposed to the atmosphere. The 

 saturation values are plotted against independent accurate measure- 

 ments of the partial pressure of oxygen in the arterial blood sample, 

 obtained from the subject, stabilized and breathing an appropriate 

 gas mixture. 



In a separate investigation, involving oxygen utilization {the 

 oxidation function) rather than oxygen transport {oxygenation 

 function), cytochrome c metabolism has been under systematic study. 

 An effective micro spectrophotometry technique has been designed 

 for this purpose, and partial hepatectomy in the rat has been adapted 

 as a metabolic procedure. Data are presented in support of the view 

 that the thyroid gland {thyroxine) has a regulatory control on the 

 concentration of cytochrome c in all tissues. 



A recent writer 1 , presumably thinking that haemoglobin is so wonder- 

 ful that it is good enough to eat, has described the work on the 

 crystalline structure of horse haemoglobin 2 ' 3 in these terms : ' The 

 general picture of the molecule is thus two hydrophobic sandwiches 

 pressed together and capable of being divided along the mid-hydro- 

 philic plane '. I suppose that when the latest studies of the Cambridge 

 investigators 4 are reviewed by this commentator he might be tempted 

 to extend his simile, and, in the American idiom, describe the 

 haemoglobin of man as a ' double decker ' or, perhaps, a ' club 

 sandwich '. It seems to me that such culinary descriptions, no doubt 

 intended to stimulate the popular appetite, overshoot the mark, and 

 miss the intent of Lord Kelvin's cogently expressed view that it isn't 

 science unless ' you can measure what you are speaking about, and 

 express it in numbers '. 



For many years past in our laboratory we have attempted to measure 

 .haemoglobin and related substances more accurately by means of the 



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