The activity of the lithium—sodium countertransport system in erythrocytes in depression and mania

The activity of the lithium-sodium countertransport system in erythrocytes was estimated in 16 control subjects and 28 patients suffering from affective disorders (11 bipolar, 17 unipolar) during depression, mania and remission. In all the patients studied, mean estimates of countertransport were significantly lower during an episode than after remission, with low values occuring more frequently in mania than in depression in bipolar patients. The mean values in patients with affective disorders but who were in remission remained lower than those of control subjects. Lowest values occured more frequently in patients with bipolar than in those with unipolar illness. The possible physiological significance of reductions in the activity of the lithium-sodium countertransport mechanism in red cells was discussed.