Effect of sodium-deficiency on the membrane activity of the frog's heart

Abstract

It was shown in these experiments that the minimum sodium concentration for electrical activity of the frog heart is below 10% if at the same time potassium, calcium and chloride concentrations are reduced. Action potentials with nearly normal amplitude and duration were obtained in an isotonic sucrose solution containing only 4.8 mM. sodium (4.2% of the normal). The presence of potassium, calcium or chloride decreases the action potential and finally makes the tissus inexcitable. An increase in amplitude of the action potential was observed in the presence of 10⁻⁶ adrenaline. To explain this action stimulation of the cation transport mechanism is proposed.