HOW DOES EPHEDRINE WORK?
Ephedrine acts at the norepinephrine synapse, the connection between a neuron that releases norepinephrine and a neighboring cell. Norepinephrine is stored in vesicles in the terminal of a neuron (shown in Figure 3). Normally norepinephrine (also called noradrenaline) is released in small quantities from the vesicles into the synaptic space. Then it binds to adrenergic receptors on the receiving cell, and depending on what type of receiving cell is present, e.g., a neuron or a cardiac cell, a specific response is produced. Neurons might fire, or a cardiac cell might fire to increase the heart rate. Ephedrines principal mechanism of action, like that of amphetamine, is to cause more norepinephrine to be released from its storage vesicles in the terminal of neurons (Figure 4). This increases the amount of norepineprhine in the synaptic space compared to normal conditions. More norepinephrine binds to adrenergic receptors, resulting in relaxation of the bronchioles, increased heart rate a
