• YAKHAK HOEJI
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• v.41 no.3
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• pp.370-380
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• 1997

The role of nitric oxide (NO) on the non-adrenergic non-cholinergic (NANC) relaxations induced by the short and prolonged electrical field stimulation (EFS) has been studied in the rabbit corpus cavernosum. In the presence of atropine and guanethidine the prolonged EFS (2-16 Hz) of corpus cavernosal strips precontracted with phenylephrine produced frequency-dependent relaxations, which were abolished by tetrodotoxin as shown in the relaxations induced gy the short EFS, indicating that their orgin is NANC nerve stimulation. $N^G$-nitro-L-arginine (L-NNA), inhibitor of nitirc oxide synthase, caused a concentration-dependent inhibition to the NANC relaxation, and at 100 M L-NNA the relaxation were virtually abolished. The inhibitory effect of L-NNA was reversed by L-arginine. Hemoglobin abolished the relaxations to NO and also caused a concentration-dependent inhibition of the NANC relaxation. The hemoglobin-resistant relaxation induced by EFS was eliminated by L-NNA. Methylene blue significantly reduced the NANC relaxation in a conentration-dependent manner. The NANC relaxation was not affected by a VIP-inactivating pepridase, alpha0chymotrypsin, whereas VIP-induced relaxation was completely abolished. NO- and VIP-induced relaxation were not affected by L-NNA. These results indicate that the NANC relaxation induced by prolonged EFS of the rabbit corpus cavernosum is mediated by NO-guanosine 3',5'-cyclic monophosphate pathway as shown in the relaxation induced by the short EFS, and that VIP release is not essential for the NANC relaxation of the rabbit corpus cavernosum and VIP is not involved the generation fo NO.

• YAKHAK HOEJI
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• v.41 no.4
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• pp.399-406
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• 1997

The effects of different $K^+$ channel blockers were investigated on the non-adrenergic non-cholinergic (NANC) relaxations in the circular muscle of the rabbit proximal stomach. Non-selective blockers of $K^+$ channels, 4-aminopyridine (4-AP, 3~30${\mu}M$) and tetraethylammonium (TEA, 100~1000${\mu}M$) significantly enhanced the NANC relaxations in a concentration-dependent manner. The enhancement was more prominent for the NANC relaxations induced by the electric field stimulation (EFS) with lower frequencies. Blockers of large conductance $Ca^{2+}$-activated $K^+$ channels, charybdotoxin and iberiotoxin, a blocker of small conduntance $Ca^{2+}$-activated $K^+$ channels, apamin and a blocker of ATP-sensitive $K^+$ channels, glibenclamide had no effect on the NANC relaxations, respectively. Exogeneous administration of nitric oxide (NO, 1~30${\mu}M$) caused concentration-dependent relaxations which showed a similarity to those obtained with EFS. None of the $K^+$ channel blockers had an effect on the concentration-dependent relaxation in response to NO. These results suggest that prejunctional $K^+$ channels regulate the release of NO from the NANC nerve in the rabbit proximal stomach as the inhibition of prejunctional $K^+$ channels increases the NANC relaxation induced by the EFS.

• Korean Journal of Veterinary Research
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• v.35 no.2
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• pp.279-285
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• 1995

To characterize non-adrenergic non-cholinergic(NANC) nerve mediated contractile responses in circular smooth muscle of bovine reticular groove, we investigated NANC relaxation and contraction induced by electric field stimulation to enteric nerves. In the presence of atropine($1{\mu}M$) and guanethidine($50{\mu}M$), electric field stimulation at frequency of 1 to 16Hz(square pulses, 0.5ms duration, 70V) evoked clear-cut relaxations through stimulations. Transient 'rebound contraction' was occured when the stimulus was switched off. All of the responses (relaxation and rebound contraction) were dose-dependently blocked by Nw-nitro-$_{\small{L}}$-arginine methyl ester(L-NAME), an inhibitor of nitric oxide synthesis, and methylene blue, and inhibitor of soluble guanylate cyclase. Tetraethyl ammonium(TEA), a potassium channel blocker, did not block the NANC relaxations.

• 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.

• 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.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.217-217
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• 1996

The putative role of vasoactive intestinal polypeptide (VIP) as non-adrenergic non-cholinergic (NANC) neurotransmitter has been studied in rabbit corpus cavernosum. In the presence of atropine and guanethidine the short and prolonged electrical field stimulation (EFS, 2～16 ㎐) induced a frequency-dependent relaxation which was abolished by tetrodotoxin (0.3 ${\mu}$M), a nerve conductance blocker. The neurogenic relaxant reponses were not affected in the presence of VIP-inactivating peptidase, ${\alpha}$-chymotrypsin (2 units/$m\ell$), whereas VIP-induced relaxation were completely abolished. Inhibition of nitric oxide synthase by N$\^$G/-nitro-L-arginine (10～100 ${\mu}$M) caused concentration-dependent inhibition to the neurogenic relaxant responses and at 100 ${\mu}$M the relaxations were virtually abolished. In contrast NO (3～30 ${\mu}$M) and VIP (0.001～l ${\mu}$M)-induced relaxation were unaffected. The inhibitory effect of L-NNA was reversed in the presence of L-arginine (5 mM), the precursor of the NO biosynthesis. Hemog1obin (20～60 ${\mu}$M), sequestering NO in the extracellular space, abolished the NO-evoked relaxation and also caused a concentration-dependent inhibition to the neurogenic relaxation. These observation indicate that NANC relaxation induced by prolonged EFS of rabbit corpus cavernosum is also mediated mainly by nitric oxide as same as that of short EFS, and suggest that VIP is not involved in NANC relaxation of rabbit corpus cavernosum and NO would not be produced by VIP in this tissue.

• 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.

• YAKHAK HOEJI
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• v.41 no.3
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• pp.389-398
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• 1997

Non-adenergic non-cholinergic (NANC) innervation on the circular muscle of the rabbit gastric body was investigated by observing the magnitudy of relaxations induced by the elec trical field stimulation (EFS). Strips were cut from the greater curvature of the gastric body and stimulated with 5s trains of 0.5 ms pulses at 1-20 Hz, 40 V. The EFS induced transient frequency-dependent contractons, followed by a slowly recovering relaxation ewpecially at higher frequency of the EFS. In the presence of atropine and guanethidine, the contractions were virtually abolished, while the frequency-dependent relaxations by the EFS remained unaffected. The magnitude of relaxations progressively decreased as the location of the strips gets closer to the bottom of the gastric body. The relaxations were ablished by tetrodotoxin, indicating that their orgin is the NANC nerve stimulation. NG-nitro-L-arginine (L-NNA, 10-$100{\mu}M$), the inhibitor of nitric oxide (NO)-synthase, caused a concentration-dependent inhibition of the NANC relaxations. The inhibitory effects of L-NNA were not affected gy the location of the strips and were reversed by L-arginine, the precursor of NO-biosynthesis. Hemoglobin (20-$60{\mu}M$), a NO scavenger, inhibited the NANC relaxation s in a concentration-dependent manner. This inhibition was more prominent in the NANC relaxations observed in the lower portion of the gastric body and the relaxations induced ly lower frequencies of the EFS. Methyelne blue (10-$100{\mu}M$), an inhibitor of cytosolic guanylate cyclase, markedly inhibited the NANC relaxations, almost abolishing the response at a higher dose ($100{\mu}M$). These results suggest that NANX innervation of the rabbit gastric body progeressively decrease as he location of the strips gets closer to the bottom of the gastric body, and that the NANC relaxation is primarily mediated by NO-guanosine 3',5'-cyclic monophophate (cyclic GMP).

• 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.