Ruthenium Red Increases the Amplitude of EPSPs at the Crayfish Neuromuscular Junction

Abstract

Ruthenium red is an inhibitor of ryanodine receptors (RyRs). The inhibition of these receptors in the extensor cells of a crayfish was expected to result in the inhibition of Ca²⁺release from internal stores and a decrease of excitatory postsynaptic potential (EPSP) amplitude. Having a better understanding of this process is important because calcium influences many cell processes and is involved in many pathological states and diseases. In the experiment, the nerve was stimulated at different frequencies and the EPSP amplitudes were measured intracellularly before and after the addition of Ruthenium red. The results collected were contrary to our hypothesis and showed an increase in EPSP amplitude under high frequency stimulation. This indicates that the consequences of Ruthenium red binding with other proteins may play a more significant role in altering the amplitude of EPSPs than the inhibition of RyRs. Ruthenium red is in a non-selective ligand, meaning it interacts with many proteins other than ryanodine receptors. At this point, further follow-up experiments are required to understand the specific effects of the inhibition of ryanodine receptors per se