The effect of lithium on choline transport in human erythrocytes

Erythrocytes from lithium treated patients were separated according to the time they had been circulating in the plasma. Choline transport and choline content were measured in the erythrocyte fractions separated according to age, in order to investigate the relationship between decreased choline transport and increased choline content seen in lithium treated patients. The most recently formed erythrocytes of normal subjects had the greatest choline content and the most active choline carrier. The erythrocytes of lithium treated patients had reduced choline carrier activity and increased choline content in all age bands. However the greatest accumulation of choline and least inhibited choline carrier activity was seen in the most recently formed cells. The alteration in phospholipid concentrations measured could not of themselves account for elevated erythrocyte choline levels seen in lithium treated patients. It is concluded that the increase in choline content levels in lithiated erythrocytes does not have a simple inverse relationship with the deficiency in choline transport. The inhibition of the choline carrier is caused by modification due to circulation in lithiated plasma rather than a lack of its synthesis in reticulocytes.