Platelet and erythrocyte-membrane adenosine triphosphatase activity in depressive and manic-depressive illness

An investigation of Mg2+ and (Na+ + K+)-dependent adenosine triphosphatase (ATPase) activities in the platelet and erythrocyte membrane of 44 depressive and 44 manic-depressive patients was carried out before and during (for 3 weeks to less than 1 year) drug treatment. When compared with normal controls (n = 43), the patients showed significantly elevated enzyme activities during both the drug-free and drug treatment periods. No remarkable changes in enzyme activities were observed between the drug-free and drug treatment (even long-term drug treatment) periods. Results suggest an alteration of cell-membrane activity, which may reflect changes in (1) ATP level, (2) cationic balance, (3) membrane phospholipid, or some combination thereof.