P/Q-type Calcium Channels Contribute to the Release of Neurotransmitters when N-type Calcium Channels are Inhibited in the Crayfish Neuromuscular Junction

Abstract

Neurotransmitter release is caused by an influx of calcium through voltage gated calcium channels in the presynaptic terminal. To learn more about voltage gated calcium channels, we applied Omega-Conotoxin GVIA solution to the crayfish neuromuscular junction. With this toxin, we were able to block one type of voltage-dependant calcium channel, the N-type calcium channel. We predicted that the excitatory post synaptic potential (EPSP) amplitude would decrease, but not disappear completely, because of the compensation of calcium ion influx by the P/Q-type calcium channels. We found that the EPSP amplitude decreased significantly, recovered slightly, and then gradually decreased again following the application of Omega-Conotoxin GVIA solution.