Purines and peptides

The Purine transmitters are ATP and adenosine. The ATP acts on ionotropic receptors and is excitatory on smooth muscle and neurons. It is occupied in transmission in hippocampus, by the autonomic neurons, sensory neurons and is occupied in pain signaling. It is inactivated enzymically. The Adenosine is not accumulated in vesicles or released in a calcium dependent way. It is produced from ATP and ADP and acts on metabotropic receptors. It is most likely the molecule responsible for physiological execution of seizure activity. And it is inactivated by the re-uptake.

There are more than 50 peptides transmitters. They are assembled by amino acid homology and by derivation from a general precursor. The Peptides are packaged into vesicles, subject to the posttranslational procedure and moved by axoplasmic transport to nerve terminals for the secretion.