• Archives of Pharmacal Research
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• v.18 no.2
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• pp.121-128
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• 1995

The role of nitric oxide (NO) in non-adrenegic non-cholinergic (NANC) neurotransmission was studied on circular muscle strips of the dorsal part of the fuinea-pig gastric fundus. In the presence of atropine and guanethidine, a low frequency-dependent relaxsations which were not affected by adrenergic and cholinergic blockage but abolished by tetrodotoxin. $N^G$-nitro-L-arginine (L-NNA), a stereospecific inhibitor of NO-biosynthesis, inhibited the relaxations induced by electrical stiumulations but not the relaxations to exogenous nitric oxide. The effect of L-NNA was prevented by L-arginine, the precursor of the NO biosynthesis but not by its enantiomer, D-arginine. Exgenous administration of No caused concentration -dependent relaxations which showed a similarity to those obtained with electrical simultaion. Hemoglobin, a NOscavenger, abolished the NO-induced relaxations and also markedly reduced those induced by electrical simultaion. The inhibitory effect os hemoglobin was similar to that of L-NNA. Application of ATP caused weak relaxations compared with those to electrical stimultaion, which were unaffected by L-NNA. Exogenously applied vasoactive intestinal polypeptide (VIP) induced concentration-dependent relaxation which was not affected by L-NNA. These results suggest that NO is produced and released mainly as a neurotransmitter from enteric neurons during NANC relaxation induced by low frequencies and short trains of electrical simulation and has a main role in NANC neurotransmission at relaxation induced by these electrical simultaions in the guinea-pig gastric fundus.

• Archives of Pharmacal Research
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• v.29 no.5
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• pp.400-404
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• 2006

This study examined the effect of Gamma-Amino butyric acid (GABA) and selective GABA receptor related drugs on the electrically stimulated relaxation in the lower esophageal sphincter muscle (LES) of a cat. Tetrodotoxin $(10^{-6}\;M)$ suppressed the electrically stimulated (0.5-5 Hz) relaxation of the LES. However, guanethidine $(10^{-6}\;M)$ and atropine $(10^{-6}\;M)$ had no effect indicating that the relaxations were neurally mediated via the nonadrenergic and noncholinergic (NANC) pathways. NG-nitro-L-arginine methyl ester ($10^{-4}M$, L-NAME) also inhibited the relaxant response but did not completely abolish the electrically stimulated relaxation with 60% inhibition, which suggests the involvement of nitric oxide as an inhibitory transmitter. This study examined the role of GABA, an inhibitory neurotransmitter, on neurally mediated LES relaxation. GABA ($10^{-3}-10^{-5}M$, non selective receptor agonist), muscimol ($10^{-3}-10^{-5}M$, GABA-A agonist), and baclofen ($10^{-3}-10^{-5}M$, GABA-B agonist) had no significant effect on the electrically stimulated relaxation. Moreover, bicuculline ($10^{-5}M$, GABA-A antagonist) and phaclofen ($10^{-5}M$, GABA-B antagonist) had no inhibitory effect on the electrically stimulated relaxation. This suggests that GABA and the GABA receptor are not involved in the electrically stimulated NANC relaxation in the cat LES.

• YAKHAK HOEJI
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• v.38 no.2
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• pp.149-157
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• 1994

The role of nitric oxide(NO) as neurotransmitter in non-adrenergic non-cholinergic (NANC) relaxation induced by electrical stimulation has been studied in circular muscle strips of the rabbit gastric fundus. In the presence of atropine and guanethidine, low frequency$(1{\sim}20\;Hz)$ and short trains (5s) of electrical stimulation induced the frequency-dependent relaxations which were not affected by adrenergic and cholinergic blockage, but abolished by tetrodotoxin, a nerve conductance blocker. L-NNA, a stereospecific inhibitor of NO biosynthesis, inhibited the relaxations induced by electrical stimulation but not affected the relaxation to exogenous NO. The effect of L-NNA was prevented by L-arginine, the precursor of the NO biosynthesis, but not by its enantiomer, D-arginine. Exogenous administration of NO$(10{\sim}100\;{\mu}M)$ caused the concentration-dependent relaxation which showed a similarity to those obtained with electrical stimulation. Hemoglobin, a NO scavenger, abolished the NO-induced relaxations and also markedly inhibited those evoked by electrical stimulation. Application of adenosine triphosphate$(1{\sim}10\;{\mu}M)$ induced concentration-independent contractions, but in high dose caused temporary contraction followed by relaxation which was not affected by L-NNA. Exogenous vasoactive intestinal polypeptide$(10{\sim}100\;nM)$ induced the concentration-dependent relaxation, while its effects were slower in onset and more persistent than those induced by short trains and low frequencies of electrical stimulation. Based on above results, it is suggested that NO is the principal neurotransmitter of NANC nerve at relaxation induced by short trains and low frequencies of electrical stimulation in the rabbit gastric fundus.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.783-796
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• 1997

The relaxation induced by stimulation of the inhibitory non-adrenergic, non-cholinergic (iNANC) nerve is mediated by the release of iNANC neurotransmitters such as nitric oxide (NO), vasoactive intestinal peptide (VIP) and adenosine triphosphate (ATP). The mechanisms of NO, VIP or ATP-induced relaxation have been partly determined in previous studies, but the detailed mechanism remains unknown. We tried to identify the nature of iNANC neurotransmitters in the smooth muscle of guinea pig ileum and to determine the mechanism of the inhibitory effect of nitric oxide. We measured the effect of NO-donors VIP and ATP on the intracellular $Ca^{2+}$ concentration$([Ca^{2+}]_i)$, by means of a fluorescence dye(fura 2) and tension simultaneously in the isolated guinea pig ileal smooth muscle. Following are the results obtained. 1. Sodium nitroprusside $(SNP:10^{-5}\;M)$ or S -nitro-N-acetyl-penicillamine $(SNP:10^{-5}\;M)$ decreased resting $[Ca^{2+}]_i$ I and tension of muscle. SNP or SNAP also inhibited rhythmic oscillation of $[Ca^{2+}]_i$ and tension. In 40mM $K^+$ solution or carbachol ($(CCh:10^{-6}\;M)$-induced precontracted muscle, SNP decreased muscle tension. VIP did not change $[Ca^{2+}]_i$ and tension in the resting or precontracted muscle, but ATP increased resting $[Ca^{2+}]_i$ and tension in the resting muscle. 2. 1H-[1,2,4]oxadiazol(4,3-a)quinoxalin-1-one $(ODQ:1\;{\mu}M)$, a specific inhibitor of soluble guanylate cyclase, limited the inhibitory effect of SNP 3. Glibenclamide $(10\;{\mu}M)$, a blocker of $K_{ATP}$ channel, and 4-aminopyridine (4-AP:5 mM), a blocker of delayed rectifier K channel, apamin $(0.1\;{\mu}M)$, a blocker of small conductance $K_{Ca}$ channel had no effect on the inhibitory effect of SNP. Iberiotoxin $(0.1\;{\mu}M)$, a blocker of large conductance $K_{Ca}$ channel, significantly increased the resting $[Ca^{2+}]_i$, and tension, and limited the inhibitory effect of SNP. 4. Nifedipine $(1\;{\mu}M)$ or elimination of external $Ca^{2+}$ decreased not only resting $[Ca^{2+}]_i$ and tension but also oscillation of $[Ca^{2+}]_i$ and tension. Ryanodine $(5\;{\mu}M)$ and cyclopiazonic acid $(10\;{\mu}M)$ decreased oscillation of $[Ca^{2+}]_i$ and tension. 5. SNP decreased $Ca^{2+}$ sensitivity of contractile protein. In conclusion, these results suggest that 1) NO is an inhibitory neurotransmitter in the guinea pig ileum, 2) the inhibitory effect of SNP on the $[Ca^{2+}]_i$ and tension of the muscle is due to a decrease in $[Ca^{2+}]_i$ by activation of the large conductance $K_{Ca}$ channel and a decrease in the sensitivity of contractile elements to $Ca^{2+}$ through activation of G-kinase.

• Advances in pediatric surgery
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• v.11 no.1
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• pp.9-18
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• 2005

Abnormal distribution of enteric nerves such as adrenergic, cholinergic and non-adrenergic non-cholinergic nerves (NANC) may cause the failure of relaxation at the involved bowel segment in Hirschsprung's disease (HD). Nitric oxide (NO) is a major inhibitory NANC neurotransmitter in the gastrointestinal tract. NO is synthesized by activation of nNOS (neuronal nitric oxide synthase) in the intramural ganglion cells and regulates bowel movement. To assess the distribution of nNOS in HD, immunohistochemical staining to nNOS was utilized on paraffin embedded specimens. Ten control colon specimens were tested for feasibility of staining. Immunohistochemisrty was done on ganglionic colon as well as aganglionic segment of 15 patients with HD. nNOS immunoreactivity was observed in the neuronal cells, small cells and nerve fibers in the muscle layer and submucosal neuronal cells of control specimens. This finding was also observed in the ganglionic segments of HD. But, there was no nNOS immunoreactivity in aganglionic segments of HD. In conclusion nNOS immunohistochemical staining of paraffin embedded specimen is feasible and reliable. And the results suggest that the relaxation failure of the aganglionic bowel in HD is related to the absence of nNOS containing cells and nerve fibers.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.3
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• pp.303-313
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• 1997

The role of the lower esophageal sphincter(LES) is characterized by the ability to maintain tone and to relax allowing the passage of a bolus. It is known that LES relaxation during swallowing may be induced by the cessation of the tonic neural excitation and the activation of non-adrenergic, non-cholinergic(NANC) inhibitory neurons. Furthermore, it is generally accepted that the relaxation of the smooth muscle is mediated primarily by the elaboration of adenosine 3',5'-cyclic monophosphate(cyclic AMP) and guanosine 3',5'-cyclic mono-phosphate(cyclic GMP) via activation of adenylate cyclase and guanylate cyclase, respectively. It is thus possible that cyclic nucleotides might be a second messenger involved in neural stimulation-induced relaxation of LES, although a relationship between relaxation and changes in cyclic nucleotides after neural stimulation has not been established. The present study was performed to define the participation of cyclic nucleotides in the relaxation of LES of dog in response to neural stimulation. Electrical field stimulation(EFS) caused relaxation of the canine isolated LES strips in a frequency-dependent manner, which was eliminated by pretreatment with tetrodotoxin$(1{\mu}M)$, but not by atropine$(100{\mu}M)$, guanethidine$(100{\mu}M)$ and indomethacin$(10{\mu}M)$. The nitric oxide synthase inhibitors, $N^G-nitro-L-arginine$, $N^G-nitro-L-arginine$ methyl ester and $N^G-monomethyl-L-arginine$ inhibited EFS-induced relaxation. Additions of sodium nitroprusside, a nitrovasodilator and forskolin, a direct adenylate cyclase stimulant, caused a dose-dependent relaxation of LES smooth muscle. Effects of sodium nitroprusside and forskolin were selectively blocked by the corresponding inhibitors, methylene blue for guanylate cyclase and N-ethylmaleimide(NEM) for adenylate cyclase, respectively. Dibutyryl cyclic AMP and dibutyryl cyclic GMP caused a concentration-dependent relaxation of the LES smooth muscle tone, which was not blocked by NEM or methylene blue, respectively. However, both NEM and methylene blue caused significant antagonism of the relaxation in LES tone in response to EFS. EFS increased the tissue cyclic GMP content by 124%, whereas it did not affect the tissue level of cyclic AMP. Based on these results, it is suggested that one of the components of canine LES smooth muscle relaxation in response to neural stimulation is mediated by an increase of cyclic GMP via the activation of guanylate cyclase. Additionally, an activation of cyclic AMP generation system was, in part, involved in the EFS-induced relaxation.

• Journal of Chest Surgery
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• v.29 no.5
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• pp.487-494
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• 1996

The neurogenic responses of tracheal smooth muscles to electrical field stimulation (EFS) is biphasic, consisting firstly of cholinergic contraction followed by a slow and sustained relaxation. It is well known that a sustained relaxation involves the inhibitory non-adrenergic non-cholinergic systems. This study was done to Investigate the relaxing agents and their action mechanisms by use of an organ bath with plati- ilum . The tracheal smooth muscle relaxation due to EFS was suppressed by L-NAME, the WO (Nitric Oxide) synthase inhibitor, and these effects were reversed by L-arginine, the precursor of NO. Also, L-WAME (HG-nitro-L-arginine methyl ester) increased the basal tension. Nitroprusside, the NO-donor, suppressed the tracheal basal tension greatly. Methylene blue, the inhibitor of guanylate cyclase, decreased EFS-induced relaxations and increa ed basal tension. Forskolin and isoprenaline, which are activators of adenylate cyclase, suppressed tracheal basal tension in the same way as nitroprusside. TEA (tetraethylammonium), the non-specific K'channel blocker, and apamin, the Ca"-activated K'channel blocker, increased tracheal basal tension and EFS-induced relaxations. Our results indicate that Pr3 Is released upon stimulation of the NANC (Won Adrenergic Won Cholinergic) nerves in guinea-pig tracheal smooth muscle and that the release of NO related with the K+ channel, as well as the release of other inhibitory agents< e. g.)VIP (Vasoactive Intestinal Polypeptide), PHI (Peptide Histidine Isoleusine) > mediated via CAMP (cyclic Adenosine Monophosphate) may be Involved In sustained relaxation.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.415-421
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• 2003

It is now generally accepted that acupuncture is effective in diarrhea caused by bacterial infection. However, its effect on the intestinal smooth muscle dysfunction is not clear. Therefore, we investigated the effect of acupuncture therapy at Jiao-chao (GV-1) on the intestinal muscle dysfunction in weaning piglets orally infected by Escherichia coli. The animals are divided into four groups; 1) E. coli + no-treatment, 2) E. coli + antibiotic, 3) E. coli + acupuncture, 4) normal group. In the three E. coli infected groups, low frequency electrical field stimulation (EFS, 1 Hz) provoked triphasic responses composed of initial relaxation followed by on-contraction and off-contraction. While in the normal group, EFS (1Hz) induced biphasic responses composed of relaxation during the stimulation and off-contraction. At the high frequency (16Hz) EFS, both on-contraction and off-contraction of the E. coli + antibiotic, E. coli + acupuncture and the normal group were larger than those of the E. coli + no-treatment group. In the non-adrenergic non-cholinergic (NANC) condition, only biphasic responses occurred to EFS in all experimental groups and the off-contraction of E. coli + antibiotic, E. coli + acupuncture and the normal group were larger than those of the E. coli + no-treatment group. The response to carbachol of those three groups was also significantly greater than that of the E. coli + no-treatment group. These results suggest that acupuncture is as effective as antibiotic in the dysfunction of colonic circular muscle caused by E. coli infection. The maintenance of contractile neuromuscular transmission seems to be involved in the mechanism of the acupuncture effects on diarrhea.