Lack of effects of thyroid hormones on human erythrocyte acetylcholine esterase.

Effects of thyroid hormones and their metabolites such as L-T1, L-T2, L-T3 and L-T4 on human erythrocyte acetylcholine esterase were studied. The activity of the enzyme of intact erythrocytes was not affected by these hormones, though studied under various conditions. The physiological significance of the binding of these hormones to erythrocyte membranes remains unclear. Our results indicate that the acetylcholine esterase is not a suitable enzyme for cytochemical bioassay for thyroid hormones.