[Effect of colchicine on rat neuromuscular transmission]

The function of the microtubules (MTs) beneath the postsynaptic membrane was studied in the isolated non-uniform stretched muscle preparation of rat diaphragm with the use of colchicine. After exposure to this drug, the amplitude of miniature endplate potential (MEPP), the mean quantal contents and mean amplitude of endplate potentials (EPPs) elicited by 10 Hz and 50 Hz stimulation and the amplitude of acetylcholine potentials (AChP) were decreased significantly, but the frequency of MEPP, membrane potential and the time course of EPP and AChP remained unchanged. These results indicate that colchicine suppresses the responses of acetylcholine receptors (AChR). No such effects were observed with colchicine's isomer lumicolchicine. It is suggested that the MTs beneath the postsynaptic membrane may be involved in the responsive process of AChR.