DISTRIBUTION OF LACTATE BETWEEN THE CORPUSCLES AND THE PLASMA IN BLOOD

¹ The Department of Physiology, University of Edinburgh

1. The ratio of the concentration of lactate in the corpuscles to that in the plasma (C/P ratio) is 0·6-0·9 in the blood of resting animals (cat, horse, man).

2. In the blood of fatigued animals (cat, rabbit, man) it is reduced to 0·5-0·6.

3. This change in the C/P ratio is not due to a delay in the diffusion of lactate from the plasma into the corpuscles, nor to the presence, either in the corpuscles or plasma, of some indiffusible substance estimated as lactate.

4. The C/P ratio is raised by (a) increased partial pressure of carbon dioxide; (b) decreased partial pressure of oxygen; (c) increased H-ion concentration These facts lead to the conclusion that a "lactate shift" analogous to the "chloride shift" occurs during each respiratory cycle of the blood, which may become of importance in connexion with the buffering of the blood in conditions of severe oxygen debt.

5. The C/P ratio is reduced by an increased concentration of lactate in the whole blood.

6. The increased lactate content of the blood occurring in conditions of oxygen debt is shown to be more than sufficient to account for the fall observed in the C/P ratio. The discrepancy is at least partly explained by the opposing effects of the simultaneous changes in carbon dioxide and oxygen partial pressures.