The Effect of Muscarine on the Sodium Calcium Exchanger and Excitatory Postsynaptic Potentials in the Neuromuscular Junction of Crayfish Neurons

Abstract

Muscarine is a chemical that has been found to continually activate the sodium calcium exchanger of neurons. This experiment tested whether muscarine affected the mechanisms of the sodium calcium exchanger in the neuromuscular junction of crayfish. Using paired pulse facilitation, EPSPs were recorded from crayfish muscles after stimulation at 15 and 20ms delays. Concentrations of 10 and 20M muscarine solutions were added to the crayfish bath to see if muscarine had an affect on the amplitude of the second EPSP of the paired pulse set relative to the first EPSP. Muscarine was known to continually activate the sodium calcium exchanger in rat brain cells and frog muscle cells, reducing the overall amount of residual calcium in the cell, and therefore reducing the amount of neurotransmitters released affecting the size of the second EPSP of the paired pulse facilitation (less is known about muscarine in crayfish muscle cells). After inconsistent results were obtained, we concluded that the muscarine had a minimal affect on the sodium calcium exchanger, as the amplitude differences were not as drastic as hypothesized. However, muscarine did alter the shape and overall amplitude of the EPSPs, revealing that on some level muscarine does affect the manifestation of EPSPs.