A STUDY OF SOME CONDITIONS INFLUENCING THE RATE OF EXCHANGE OF OXYGEN IN BLOOD IN VITRO

¹ Physiology Department, Edinburgh University

A tonometer is illustrated which ensures constant conditions of exposure of blood to gas mixtures for any desired interval of time, making possible a simultaneous measurement of the velocity of exchange of oxygen and carbon dioxide in whole blood.

The influence of variations in temperature, red-cell volume p. c., the relative viscosity of the blood, and in the pressure gradient of oxygen between the blood and the gas phase on the rate of exchange of oxygen by oxalated blood in vitro was investigated. It was found that

1. An increase of temperature, or a reduction in the relative viscosity of the blood or in its relative red-cell volume augmented the rates of uptake and release of oxygen.

2. The increases in the rate of exchange observed with rises of temperature from 20-38°C., or with reductions in the relative red-cell volume corresponded to just such increases in the rate of exchange as would be expected from the resulting alterations in the relative viscosity of the blood.

3. The rate of oxygen uptake varied in almost direct proportion with the partial pressure of oxygen to which the blood was exposed. The rate of oxygen release did not so accurately reflect the pressure gradient of oxygen between the blood and the gas phase.

Note:

We wish to thank Professor I. de Burgh Daly for his kindness in providing the laboratory facilities without which this work could not be carried out, and Dr. P. Eggleton for his constant interest and very valuable criticism. Our thanks are also due to Dr. A. Jablonski, Lecturer in Physics at the Polish School of Medicine, University of Edinburgh, for his great assistance in the mathematical treatment of the results.

The expenses of this work were partially covered by a grant from the Polish Medical Air Council to J. F.