Osmotic behavior of erythrocytes from patients with a major affective disorder. A freeze-fracture electron microscopic study

Previously we have demonstrated a state-dependent decrease in the number of membrane vesicles in erythrocytes from patients with a major depressive episode. We now report an increase in the number of membrane vesicles during a manic episode as well as a reduction during lithium treatment and we also present data suggesting that the number of erythrocyte membrane vesicles in the affective disorders is dependent on osmotic shrinkage due to the freezing for freeze-etch electron microscopy. Although caution is required since the interrater reliability of the measurement of osmotic strain was insufficient in the mid range where it was tested, we do not think this invalidates the differences in osmotic strain found in the low and high ranges during depressive and manic episodes respectively. These findings warrant the use of more precise techniques in studies of the osmotic behavior of erythrocytes from patients with a major affective disorder.