2-(4-phenylpiperidino) cyclohexanol (AH5183) decreases quantal size at the frog neuromuscular junction

AH5183 was studied because it inhibits acetylcholine transport into synaptic vesicles. The drug apparently is a slow-acting anti-cholinesterase, so further experiments were performed with this enzyme inhibited. Soaking for hours in AH5183 in Ringer does not decrease quantal size. However, a few minutes of tetanic nerve stimulation results in a marked decrease in quantal size. Quantal size also decreased after hours in a hypertonic Ringer containing the drug.