NANC transmission

E. Nonadrenergic, Noncholinergic (NANC) Transmission Some nerve fibers in autonomic effector tissues do not show the histochemical characteristics of either cholinergic or adrenergic fibers. Some of these are motor fibers that cause the release of ATP and possibly other purines related to it. Purine-evoked responses have been identified in the bronchi, gastrointestinal tract, and urinary tract. Other motor fibers are peptidergic, ie, they release peptides as the primary transmitters (see list above under Cotransmitters). 

In the guinea-pig jejunum, co-conotoxin GVIA blocked only partially (33%) the inhibitory NANC transmission upon electrical stimulation. This was also the case at the taenia caecum (20% inhibition) [154]. In the proximal duodenum the NANC transmission was insensitive to co-conotoxin GVIA [155]. 

Therefore, cholinergic transmission at this level seems to be regulated by Ca entering through N-type Ca channels while NANC transmission is regulated by another Ca entry pathway besides N channels. 

Inhibitory NANC responses are mediated by both VIP and NO.. NO. partially mediates the airway smooth muscle relaxant effects of VIP in the isolated perfused guinea-pig lung, as NOS inhibitors prevent relaxation induced by VIP but not that induced by isoproterenol (Lilly et al., 1993b). A significant and appropriately timed increase in the NO. content of lung perfusion fluid can be measured in response to VIP (Fig. 7.4). These data support the conclusion that interactions of VIP with NO. products mediate a substantial component of iNANC transmission. In human airways, NOS stimulated as a result of iNANC neurotransmission accounts for a substantial proportion of this relaxant response. Bel-visi and co-workers have shown that the a-chymotrypsin-resistant component of the human iNANC response can be abolished by treatment with NOS inhibitors (Belvisi et al., 1992). 

I. Smova-Sloufova, F. Lednicky, A. Gemperle, and J. Gemperlova, Cote-shell (Ag)Au bimetallic nanc articles analysis of transmission electron microscopy images, Lae ynuir 16,9928-9935 (2000). 

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