Expression of nitric oxide synthase immunoreactivity by interstitial cells of the XXXX proximal colon.

@entity6708 @entity35 @entity2337 @entity235 @entity141 @entity121 @entity5612
A subpopulation of interstitial cells (ICs) are interposed between nerve terminals and smooth muscle cells in the gastrointestinal tract and may participate in neuromuscular transmission. These cells appear to be targets for NO released from enteric inhibitory nerves and respond to exogenous NO with: (i) an elevation in @entity6708 levels; (ii) an increase in intracellular @entity141 ; (iii) and release of a diffusible substance that has tentatively been identified as NO. For the latter to be possible, ICs must express a constitutive isoform of NOS. This study characterized the expression of NOS-like immunoreactivity (NOS-LI) in ICs of the @entity235 colon using 3 antibodies raised against the 2 known constitutive forms of NOS (i.e., neural ( @entity5612 ) and endothelial (eNOS) isoforms). Antibodies raised against cNOS and an antibody raised against @entity35 cerebellar @entity5612 labeled ICs along the submucosal surface of the circular muscle layer ( @entity2337 -SM), along the surface of septa that separate the circular muscle into fiber bundles ( @entity2337 -SM), and in the myenteric region between the circular and @entity121 ( @entity2337 -MY). Another antibody raised against @entity35 cerebellar @entity5612 failed to label ICs. Cultured @entity2337 -SM also expressed NOS-LI, suggesting that this feature of the @entity2337 phenotype survives culture conditions. Arteriolar endothelial cells in the @entity235 colon were labeled with the same 2 antibodies that labeled ICs, suggesting there are significant structural similarities between NO synthases in ICs and endothelial cells. The data suggest that @entity2337 -SM and @entity2337 -MY express a constitutive form of NOS. Synthesis of NO by ICs may influence electrical rhythmicity and may serve to amplify and even propagate enteric inhibitory neurotransmission.
