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

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 cGMP levels; (ii) an increase in intracellular Ca2+; (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 canine colon using 3 antibodies raised against the 2 known constitutive forms of NOS (i.e., neural (nNOS) and endothelial (eNOS) isoforms). Antibodies raised against cNOS and an antibody raised against rat cerebellar nNOS labeled ICs along the submucosal surface of the circular muscle layer (IC-SM), along the surface of septa that separate the circular muscle into fiber bundles (IC-SM), and in the myenteric region between the circular and longitudinal muscle layers (IC-MY). Another antibody raised against rat cerebellar nNOS failed to label ICs. Cultured IC-SM also expressed NOS-LI, suggesting that this feature of the IC phenotype survives culture conditions. Arteriolar endothelial cells in the canine 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 IC-SM and IC-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.

Immunochemical detection of inducible NO synthase in human lung

Type II (inducible) nitric oxide synthase (NOS) may play an important role in pulmonary pathophysiology, yet it remains controversial whether human tissues are capable of expressing this protein. Therefore, a polyclonal antibody (8196) was raised against type II NOS from induced RAW 264.7 macrophages and used to investigate the expression of this enzyme in human lung tissue. Anti-type II NOS antibody did not cross-react with either neuronal (type I) or endothelial (type III) constitutive NOS, whereas a 130-kDa protein was detected in cytosol from induced macrophages or liver removed from lipopolysaccharide (25 mg/kg)-treated rats. Cells or tissues that lacked NOS activity did not express immunoreactive proteins. Similarly, in grossly normal human lung tissue, no immunoreactivity was detected with the anti-type II NOS antibody. In contrast, strong immunoreactivity was detected in alveolar macrophages present in lung tissue from a patient with bronchiectasis and acute bronchopneumonia. These data demonstrate that human alveolar macrophages are able to express type II NOS and support a role for this enzyme in pulmonary inflammatory pathophysiology.

Localization of nitric oxide synthase in canine ileocolonic and pyloric sphincters

The distribution of neurons containing NAD-PH-diaphorase (NADPH-d) activity and nitric oxide synthase-like immunoreactivity (NOS-LI) in the canine pyloric and ileocolonic sphincters was studied. Cells within the myenteric and submucosal ganglia were positive for NADPH-d. These cells generally had the morphology of Dogiel type-I enteric neurons, however, there was some diversity in the morphology of NADPH-d-positive neurons in the myenteric plexus of the pylorus. Intramuscular ganglia were observed in both sphincters, and NADPH-d was found in a sub-population of neurons within these ganglia. Dual staining with an antiserum raised against nitric oxide synthase (NOS) demonstrated that almost all cells with NOS-LI were also NADPH-d positive. Varicose fibers within ganglia and within the circular and longitudinal muscle layers also possed NOS-LI and NADPH-d activity. Dual staining with anti-VIP antibodies showed that some of the NADPH-d-positive cells in the myenteric and submucosal ganglia also contained VIP-LI, but all VIP-LI-positive cells did not express NADPH-d activity. These data are consistent with recent physiological studies suggesting that nitric oxide serves as an inhibitory neurotransmitter in the pyloric and ileocolonic sphincters. The data also suggest that VIP is expressed in a sub-population of NADPH-d-positive neurons and may therefore act as a co-transmitter in enteric inhibitory neurotransmission to these specialized muscular regions.

Immunohistochemical localization of 3',5'-cyclic guanosine monophosphate in the canine proximal colon: responses to nitric oxide and electrical stimulation of enteric inhibitory neurons

There is growing evidence that nitric oxide serves as a neurotransmitter released from enteric inhibitory nerves in the gastrointestinal tract. The distribution of nitric oxide synthase suggests that nitric oxide may also be a neurotransmitter within enteric ganglia. Since many actions of nitric oxide are mediated by stimulation of soluble guanylate cyclase and a subsequent increase in 3',5'-cyclic guanosine monophosphate (cGMP) concentration, targets for nitric oxide in the canine proximal colon were investigated by immunohistochemical localization of cGMP. In the presence of phosphodiesterase inhibitors (M&B 22948, 100 microM and 3-isobutyl-1-methyl-xanthine, 1 mM), exogenous nitric oxide and electrical field stimulation caused an accumulation of cGMP-like immunoreactivity in several cell-types including colonic smooth muscle cells. cGMP-like immunoreactivity was also observed in a subpopulation of neurons in both myenteric and submucosal ganglia. Sequential labeling with the NADPH diaphorase technique showed that 94% of neurons that responded to exogenous nitric oxide with an increase in cGMP-like immunoreactivity were NADPH diaphorase negative. None of the myenteric neurons that responded to electrical field stimulation with an increase in cGMP-like immunoreactivity were NADPH diaphorase positive, and only one submucosal neuron with cGMP-like immunoreactivity was also NADPH diaphorase positive. The electrical field-stimulated increase in cGMP-like immunoreactivity was blocked by nitroarginine (100 microM). An increase in cGMP-like immunoreactivity also occurred in interstitial cells located at the submucosal surface of the circular muscle layer. These cells are interposed between nerve varicosities and smooth muscle cells and may partially mediate neuromuscular transmission. Sodium nitroprusside and nitric oxide also caused an accumulation of cGMP-like immunoreactivity in smooth muscle cells of intramural arterioles and venules. The results of this study further support the role of nitric oxide as a neurotransmitter in colonic muscles, and provide support for the hypothesis that interstitial cells are functionally innervated by enteric inhibitory neurons. The data also suggest that nitric oxide may serve as a neurotransmitter in enteric ganglia.

Identification of interstitial cells in canine proximal colon using NADH diaphorase histochemistry

In gastrointestinal muscles special cells, referred to an interstitial cells, may be involved in pacemaking and transduction of inputs from the enteric nervous system. We have used a modification of the NADH diaphorase method to characterize the distribution of interstitial cells in the muscularis externa of the canine colon. The staining product of the NADH diaphorase reaction is useful because it allows light and electron microscopic studies to be performed with the same marker. Therefore rigorous identification of the cells observed at the light microscopic level could be made by electron microscopy. We were able to label at least three classes of interstitial cells: (1) at the submucosal surface of the circular muscle layer; (2) within the thickness of the circular and longitudinal muscle layers; and (3) in the region of the myenteric plexus. This technique also labeled cell bodies and initial segments of processes of Dogiel type II neurones in enteric ganglia. Nerve fibres within the muscle layers did not exhibit NADH diaphorase activity. This study has identified the interstitial cells within the circular and longitudinal muscle layers and shows the arrangement of these cells in a three-dimensional network.

NADPH diaphorase and nitric oxide synthase colocalization in enteric neurons of canine proximal colon

Considerable evidence has recently been presented that suggests that nitric oxide (NO) is a nonadrenergic noncholinergic (NANC) neurotransmitter in gastrointestinal tissues. One of the criteria that must be satisfied before this hypothesis can be accepted is that enteric neurons must be shown to contain the enzymatic apparatus necessary to synthesize NO. Specific antibodies have been developed for NO synthase (NOS) isolated from rat cerebellum, and studies have shown that NOS copurifies and colocalizes with NADPH diaphorase activity, a commonly used neural marker. We used antibodies raised against the cerebellar NOS to determine the distribution of NOS-like immunoreactivity (NOS-LI) in enteric neurons of the canine proximal colon. We also tested whether NADPH diaphorase staining would label the population of neurons containing NOS-LI in this species. A subpopulation of neurons in myenteric and submucosal ganglia displayed NOS-LI and were colabeled with NADPH diaphorase. Labeled neurons had morphological characteristics similar to the Dogiel type I morphology. Cryostat sections showed NOS-positive nerve trunks throughout the circular and longitudinal muscle layers, but a high density of NOS-LI was observed within the submucosal pacemaker region, as predicted from physiological studies. These studies provide the first morphological support for the hypothesis that NO serves as a NANC neurotransmitter in the canine colon. The study also shows that the NADPH diaphorase reaction provides a useful method to label cells with NOS-LI.

Treatment of 910 cases of atrophic gastritis with wei you decoction

In treatment of 910 cases of chronic atrophic gastritis with Wei You Decoction, the overall effective rate was 96.9%. The disease was considered as due to deficiency of vital energy with stagnation of cold, and therefore treatment was to invigorate blood circulation. The Wei You Decoction had functions of replenishing vital energy, warming the middle burner, invigorating blood circulation, and resolving stasis, thus reversing the morbid process in the gastric mucosa. It was nontoxic, and the side-effects were minimal. The therapeutic effect was prompt and persistent. No malignant change was observed after taking the drug.