Inhibition of the reverse mode of the sodium/calcium exchanger reduces facilitation of paired excitatory postsynaptic potentials in the crayfish neuromuscular junction

Abstract

Changes in neurons account for various types of learning. One way this learning is accomplished on a cellular level is through facilitation of excitatory postsynaptic potentials (EPSPs). Calcium, the ion responsible for neurotransmitter release and the amplitude of EPSPs, is regulated through various cellular mechanisms including the sodium/calcium exchanger. By inhibiting the reverse mode of the sodium/calcium exchanger we examined the contributions of the exchanger to facilitation, measuring both the first EPSP and changes in facilitation. KB-R7943, the exchanger inhibitor, effectively decreased facilitation while leaving the first EPSPs unaffected. Our results suggest that further experiments should be directed towards measuring the effect of KB-R7943 on the first EPSP while inhibiting K channels and thereby increasing the duration of the action potential.