Tetraphenylphosphonium (TPP+) によるシナプトソームの膜電位の測定

The concentration of tetraphenylphosphonium (TPP+) was measured under various controlled conditions with a TPP-selective electrode. Assuming that membrane potential in synaptosomes is depolarized replacement of sodium with potassium in the physiological saline, we estimated the amount of TPP bound to plasma membranes and mitochondria in synaptosomes. About 50% of TPP+ was bound to plasma membranes and about 45% was mitochondria in synaptosomes. Membrane potentials in synaptosomes under various conditions were calculated by the Nernst equation using these values. The resting potential of synaptosomes was estimated to be-70 to-90mV.The propriety of these values obtained and of the method, for calculation were discussed.