Ruthenium red does not affect paired-pulse facilitation at the crayfish neuromuscular junction

Abstract

Paired-pulse facilitation (PPF) of neurotransmitter release occurs when synapses in crayfish and rat hippocampi undergo paired stimuli separated by approximately 50ms. The activation of ryanodine receptors (RyRs) on the endoplasmicreticulum is believed to facilitate PPF by releasing calcium from intracellular stores in response to calcium influx. In order to better understand the role of internal calcium levels in synaptic plasticity, we inhibited the ryanodine receptors with ruthenium red and induced PPF. Our results did not support our dual hypotheses that ruthenium red would decreaseexcitatory postsynaptic potential (EPSP) amplitude and would increase PPF.