Action of barbiturates on activity of acetylcholinesterase from synaptosomal membranes

The acetylcholinesterase from synaptosomal membranes is inhibited by anesthetics: Nembutal, brietal, and thiopental. Nembutal and brietal decrease theK_m for acetylthiocholine, without changes inV_max. A noncompetitive type of inhibition is produced by thiopental. This anesthetic decreases Arrhenius plot discontinuity by about 4°C and increases activation energies. Nembutal and brietal do not change Arrhenius plot discontinuities, but they increase activation energies. These results suggest that barbiturates change lipid-protein interactions in synaptosomal membranes.