[Effect of chromium ions on the function of neuromuscular junctions]

It has been shown on neuro-muscular preparations of frog sartorius muscle that chromium ions in the concentrations 1-4 x 10(-6) g/ml strengthen spontaneous and evoked transmitter release. Cr3+ ions in the concentrations above 4 x 10(-6) g/ml decrease the membrane potential of muscle fibres, decrease the quantum content of the end plate potentials. Experiments on a single Ranvier node have shown that Cr3+ ions decrease the amplitude, increase the rate and duration of the action potential of a nerve fibre. It is concluded that chromium ions produce a pronounced effect on synaptic transmission, which differs significantly from the action of manganese, cobalt and nickel ions.