[The functional heterogeneity of the synapses of the frog sartorius muscle]

Three main types of neuro-muscular junctions were revealed by means of the e.p.p. quantum content and the e.p.p. dynamics during high-frequency stimulation. Heterogeneity of synaptic apparatus seems to be mainly due to different intensities of quantum release. Subctances facilitating neuro-muscular transmission (Ca2+ ions, imidazol) were more effective in myoneural junctions with low e.p.p. quantum content, while depressing chemical agents (acetylcholine, tubocurarine) exerted a more potent effect in junctions with high quantum content.