Non-adrenergic, non-cholinergic inhibitory mechanisms

Many smooth muscles possess an autonomic innervation that cannot be classified as cholinergic or adrenergic — the nerves are often termed non-adrenergic, non-cholinergic (nanc). One of the first clues to their existence came from the work of Langley & Anderson (1895) who described atropine-resistant responses to stimulation of the sacral parasympathetic outflow. In recent years the number of organs found to possess an autonomic nanc innervation, usually in addition to the more familiar adrenergic and/or cholinergic innervation, has increased greatly, as has the number of suggested putative transmitters, which include amino acids, amines and a range of polypeptides, as well as purine nucleotides. To date, no nanc transmitter has been identified with certainty, but it has become clear that we are dealing not with a single extra transmitter substance, but with a variety of different ones in different organs and species. Some may act as cotransmitters, supporting or modulating the function of the main transmitter. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.