Neurons presynaptic

P/Q-type Cav2.1 t lA Neuron presynaptic terminals, heart, brain... 

Mechanism of Action An antidepressant that appears to inhibit serotonin and norepinephrine reuptake at CNS neuronal presynaptic membranes is a less potent inhibitor of dopamine reuptake. Therapeutic Effect Relieves depression. Pharmacokinetics Well absorbed from the G1 tract. Protein binding greater than 90%. Extensively metabolized to active metabolites. Excreted primarily in urine and, to a lesser extent, in feces. Half-life 8-17 hr. 

Mechanism of Action A tricyclic antidepressant that blocks reuptake of the neu-retransmitters norepinephrine and serotonin at neuronal presynaptic membranes, increasing their availability at postsynaptic receptor sites. Therapeutic Effect Relieves depression. 

Figure 11.3 Diagram of autonomic and somatic motor neurons. Presynaptic neurons are depicted with solid cell bodies. Postsynaptic neurons are speckled. The neurotransmitter released by the presynaptic neuron and the type of receptor it activates are listed below each synapse.

Secretory cells often release vesicles spontaneously at a low rate whereas release rates increase when a stimulus arrives at the release site. For example, miniature synaptic potentials represent spontaneous release from the neuronal presynaptic terminal (Katz, 1966 Stevens, 1993). In contrast, sperm have only one secretory vesicle and, as discussed previously, cells that complete the acrosome reaction prior to egg contact are infertile. This problem may be circumvented, in part, by the fact that large numbers of sperm are produced by mammals, thereby minimizing the consequences of premature acrosome reactions in large populations. However,... 

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