Biomembrane cooperative enzymes. In vivo modulation of rat erythrocyte acetylcholinesterase by insulin in normal and diabetic conditions.

The present study investigated the effect of insulin in vivo on the changes in the cooperativity of a membrane-bound enzyme. The allosteric inhibition by F- of the erythrocyte membrane acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) was studied during intravenous glucose tolerance tests in control and alloxan-induced diabetic rats. In the former group, the value of n decreased from 1.6 to 1.0 whereas it remained about 1.6 in the latter groups. Intravenous injection of insulin (30 U/kg) decreased the values of n in both groups. It is suggested that the in vivo insulin action on membrane cooperative enzymes could also take place in insulin target cells.