Nitrendipine and Cadmium Decrease Synaptic Transmission in the Crayfish Neuromuscular Junction While ?-conotoxin Does Not

Abstract

Calcium channels have proven to be essential in the optimal functioning of chemical neurotransmission. Previous researchers have found that different types of channels exist and are inhibited by various chemicals. We tested three different calcium channel blockers - cadmium, Nitrendipine, and ?-conotoxin and using intracellular recording techniques witnessed their effects on the excitatory post-synaptic potentials (EPSPs) in the crayfish neuromuscular junction. We hypothesized that all of the blockers would decrease the EPSP amplitudes, and that cadmium, the general blocker, and ?-conotoxin, the N-type channel blocker, would have similar effects in decreasing the amplitude more than would Nitrendipine, the L-type blocker. This hypothesis proved incorrect, as ?-conotoxin increased the average EPSP amplitude, suggesting perhaps compensation for the blocked channels or that the chemical we used was too old to be effective.