Mechanism of potentiation of tyramine effects by monoamine oxidase (MAO) inhibition. In the control situation (above) tyramine is transported into axon terminal by the noradrenaline transporter (NET) and noradrenaline (NA) is transported out, but few Na molecules are available in the soluble cytoplasmatic pool because of the activity of intraneuronal MAO-A. Following MAO inhibition (below) the size of the soluble NA pool increases resulting in a much greater chance for reverse transport. Note that some NA is also displaced from the granular storage pool by tyramine.