Potassium Induced Release of Transmitter at the Human Neuromuscular Junction

Elmqvist, D. Potassium induced release of transmitter at the human neuromuscular junction. Acta physiol. scand. 1965. 64. 340–344. – When the release of ACh quanta from the human intercostal motor nerve terminals, recorded as miniature end‐plate potentials (m. e. p. p. s), was enhanced by raising the potassium ion concentration, the increased rates were only sustained if release rates were limited to not more than 150 m. e. p. p. s/sec either by not using higher concentrations of KCl than 30 mM, or by reducing release with increased magnesium and lowered calcium concentrations when higher potassium ion concentrations were used. If higher rates of release were allowed to occur in the presence of 40 or 50 mM KCl, the release rates subsequently declined to very low levels. The total number of quanta released by 40 or 50 mM KCl corresponded to the amount of ACh estimated to be present in the motor nerve terminals.