The effect of poneratoxin on neuromuscular transmission in the rat diaphragm.

The effect of the ant venom neuropeptide--poneratoxin (PoTX)--on neuromuscular transmission in rat diaphragm tissue was studied by means of intracellular recordings of spontaneous miniature endplate potentials (MEPPs) and of nerve evoked endplate potentials (EPPs). A 2 microM concentration of PoTX caused a pronounced but transient increase in MEPPs frequency. Moreover, within the first few minutes of PoTX administration, the area, rise time and half decay time of MEPPs gradually decreased, reaching steady values after 15-20 min.