Sodium-potassium, magnesium, and calcium ATPase activities in erythrocyte membranes from manic-depressive patients responding to lithium.

ABSTRACT

Erythrocyte membrane Na+-K+ adenosine triphosphatase (ATPase), Mg2+ ATPase, and Ca2+ ATPase activities were compared among 23 euthymic manic-depressive patients responding to lithium therapy and 24 healthy controls. The two groups were similar in age, sex composition, body mass index, and community background. No significant differences were noted in mean ATPase activities between the two groups. However, plasma lithium concentration correlated positively with Na+-K+ ATPase and Mg2+ ATPase activities within the patient group, and six patients with plasma lithium levels in the range of 0.85-1.2 mM had Na+-K+ ATPase activities 62% greater than the control group mean. Possible biochemical mechanisms for the effects of lithium therapy on erythrocyte membrane functions are discussed.