The Ionic Mechanism Generating the Inhibitory Postsynaptic Potential

Abstract

The effects produced in the size and direction of the IPSP by varying the initial membrane potential (Figs. 60, 65 and 66A, B) correspond precisely to the changes that would be expected if the currents generating the IPSP were due to ions moving down their electrochemical gradients. These currents would be caused to flow by increases in the ionic permeability that are produced in the specific inhibitory zones of the subsynaptic membrane under the influence of the inhibitory transmitter substance. The outwardly directed current across the inhibitory subsynaptic membrane (Fig. 58B) could be due to the outward movement of a cation such as potassium or the inward movement of an anion like chloride or to such a combination of anionic and cationic movements that there is a net outward flow of current.