• Title/Summary/Keyword: NO-cyclic GMP pathway

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Ethanol Extract of Cynanchum wilfordii Produces Endothelium-Dependent Relaxation in Rat Aorta and Anti-inflammatory Activity in Human Aortic Smooth Muscle Cells

  • Choi, Deok-Ho;Lee, Yun-Jung;Kim, Eun-Joo;Li, Xiang;Kim, Hye-Yoom;Hwang, Sun-Mi;Yoon, Jung-Joo;Lee, So-Min;Min, Eun-Kyeong;Kang, Dae-Gill;Lee, Ho-Sub
    • The Journal of Korean Medicine
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    • v.31 no.6
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    • pp.47-57
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    • 2010
  • Objective: The present study investigated the effect of ethanol extract of Cynanchum wilfordii (ECW) on vascular relaxation and vascular inflammation in rat artery isolated from rats and anti-inflammatory activity in human aortic smooth muscle cells (HASMC). Methods: Vascular tone and guanosine 3',5'-cyclic monophosphate (cGMP) production were examined in rat artery isolated from Sprague Dawley rats, in the presence of ECW. HASMC were incubated with tumor necrosis factor-alpha (TNF-${\alpha}$) or Angiotensin II for 24 h. Matrix metalloproteinase (MMP)-2 and anti-oxidant activity of ECW was investigated by pretreatment with ECW in HASMC. Results: Cumulative treatment of ECW relaxed aortic smooth muscles of rats in a dose-dependent manner. ECW-induced vasorelaxation was significantly decreased by pretreatment of L-arginine methyl ester (L-NAME) or oxadiazolo-quinoxalinone (ODQ). Furthermore, ECW treatment of thoracic aorta significantly increased cGMP production. Incubation of ECW with ODQ or L-NAME markedly decreased ECW-induced cGMP production. ECW treatment dose-dependently suppressed TNF-${\alpha}$- or Angiotensin II-induced increase in matrix metalloproteinase-2 expression in HASMC. Also, ECW exhibited 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity in vitro and reduced TNF-${\alpha}$-induced increase in reactive oxygen species production in a dose-dependent manner. Conclusions: Taken together, the results suggest that ECW exerts vascular relaxation via NO/cGMP signaling pathway and decreases MMP-2 expression via anti-oxidant activity.

Vascular Relaxation Induced by the Water Soluble Fraction of the Seeds from Oenothera Odorata (월견자 물 분획층을 이용한 혈관이완 기전에 관한 연구)

  • Kim, Hye Yoom;Lee, Yun Jung;Yoon, Jung Joo;Kho, Min Chol;Han, Byung Hyuk;Choi, Eun Sik;Park, Ji Hun;Kang, Dae Gill;Lee, Ho Sub
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.29 no.6
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    • pp.492-497
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    • 2015
  • In the present study, vasorelaxant effect of the extract of seeds of Oenothera odorata (SOO) and its possible mechanism responsible for this effect were examined in vascular tissues isolated from rats. Changes in vascular tension, 3',5'-cyclic monophosphate (cGMP) levels were measured in thoracic aorta rings from rats. Methanol extract of seeds of Oenothera odorata relaxed endothelium-intact thoracic aorta in a dose-dependent manner. A dose-dependent vascular relaxation was also revealed by treatment of ethylacetate, n-butanol, and H2O (aqua extract of seeds of Oenothera odorata , ASOO) extracts partitioned from methanol, but not by hexane extract. However, the vascular relaxation induced by ASOO were abolished by removal of endothelium of aortic tissues. Pretreatment of the endothelium-intact vascular tissues with NG-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1- one (ODQ) significantly inhibited vascular relaxation induced by ASOO. Moreover, incubation of endothelium-intact aortic rings with ASOO increased the production of cGMP. However, ASOO-induced increases in cGMP production were blocked by pretreatment with L-NAME or ODQ. The vasorelaxant effect of ASOO was attenuated by tetraethylammonium (TEA), 4-aminopyridine, and glibenclamide attenuated. On the other hand, the ASOO-induced vasorelaxation was not blocked by verapamil, and diltiazem. Taken together, the present study demonstrates that ASOO dilate vascular smooth muscle via endothelium-dependent NO-cGMP signaling pathway, which may be closely related with the function of K+ channels.

Nitric Oxide-Induced Apoptosis of Human Dental Pulp Cells Is Mediated by the Mitochondria-Dependent Pathway

  • Park, Min Young;Jeong, Yeon Jin;Kang, Gi Chang;Kim, Mi-Hwa;Kim, Sun Hun;Chung, Hyun-Ju;Jung, Ji Yeon;Kim, Won Jae
    • The Korean Journal of Physiology and Pharmacology
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    • v.18 no.1
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    • pp.25-32
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    • 2014
  • Nitric oxide (NO) is recognized as a mediator and regulator of inflammatory responses. NO is produced by nitric oxide synthase (NOS), and NOS is abundantly expressed in the human dental pulp cells (HDPCs). NO produced by NOS can be cytotoxic at higher concentrations to HDPCs. However, the mechanism by which this cytotoxic pathway is activated in cells exposed to NO is not known. The purpose of this study was to elucidate the NO-induced cytotoxic mechanism in HDPCs. Sodium nitroprusside (SNP), a NO donor, reduced the viability of HDPCs in a dose- and time-dependent manner. We investigated the in vitro effects of nitric oxide on apoptosis of cultured HDPCs. Cells showed typical apoptotic morphology after exposure to SNP. Besides, the number of Annexin V positive cells was increased among the SNP-treated HDPCs. SNP enhanced the production of reactive oxygen species (ROS), and N-acetylcysteine (NAC) ameliorated the decrement of cell viability induced by SNP. However, a soluble guanylate cyclase inhibitor (ODQ) did not inhibited the decrement of cell viability induced by SNP. SNP increased cytochrome c release from the mitochondria to the cytosol and the ratio of Bax/Bcl-2 expression levels. Moreover, SNP-treated HDPCs elevated activities of caspase-3 and caspase-9. While pretreatment with inhibitors of caspase (z-VAD-fmk, z-DEVD-fmk) reversed the NO-induced apoptosis of HDPCs. From these results, it can be suggested that NO induces apoptosis of HDPCs through the mitochondria-dependent pathway mediated by ROS and Bcl-2 family, but not by the cyclic GMP pathway.

Effects of Schisandra chinensis fruit extract and gomisin A on the contractility of penile corpus cavernosum smooth muscle: a potential mechanism through the nitric oxide - cyclic guanosine monophosphate pathway

  • Choi, Bo Ram;Kim, Hye Kyung;Park, Jong Kwan
    • Nutrition Research and Practice
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    • v.12 no.4
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    • pp.291-297
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    • 2018
  • BACKGROUND/OBJECTIVES: This study evaluated the effects and molecular mechanisms of the Schisandra chinensis fruit extract (SC) and its major compound gomisin A (GA), on the contractility of rabbit penile corpus cavernosum smooth muscle (PCCSM). MATERIALS/METHODS: PCCSM was exposed to SC or GA after appropriate pretreatment with nitric oxide synthase (NOS) blocker, guanylate cyclase blocker, adenylyl cyclase blocker or protein kinase A blocker. Subsequently, we evaluated the cyclic nucleotide in the perfusate by radioimmunoassay, protein expression level of neuronal NOS (nNOS) and endothelial NOS (eNOS) by western blot, and the interaction of SC or GA with udenafil and rolipram. RESULTS: Both SC and GA induce PCCSM relaxations in a concentration-dependent manner. Pretreatment with NOS blocker, guanylate cyclase blocker, adenylyl cyclase blocker or protein kinase A blocker result in significantly decreased relaxation. SC and GA also induce the levels of cyclic nucleotide in the perfusate in a concentration-dependent manner. Perfusion with GA also showed significantly higher levels of eNOS protein. Furthermore, the udenafil and rolipram induced relaxations of PCCSM were enhanced after exposure to SC and GA. Our results indicate that SC and GA induce the relaxation of PCCSM via the nitric oxide (NO)-cGMP and cAMP signaling pathways. CONCLUSIONS: The SC and GA are potential alternative treatments for men who want to consume natural products to ameliorate erectile function, or who do not respond to the commercially available medicines.

Inhibitory effects of xylamine on the arterial contraction in rats (흰쥐 대동맥 수축에 대한 xylamine의 억제효과)

  • Kim, Sang-Jin;Kang, Hyung-sub;Kim, Jin-shang
    • Korean Journal of Veterinary Research
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    • v.44 no.3
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    • pp.389-397
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    • 2004
  • The therapeutic efficacy of xylamine in the field of psychological medicine has been recognized for years and the drug is used to treat depression and some other conditions, but little is known about its mechanism of action on vascular system. Therefore, the present study was designed to investigate the influence of xylamine on the contractile responses of isolated rat thoracic arteries to phenylephrine(PE) and potassium chloride(KCl). Xylamine produced a concentration-dependent relaxation in PE-precontracted endothelium intact(+E) rat aortic rings, but not in a KCl-precontracted aortic rings. Also, xylamine inhibited the PE-induced contraction in concentration-dependent manner, but not in the high KCl-induced contraction in +E rings. This concentration-dependent inhibition was suppressed by the removal of the endothelium (-E). The inhibitory effects of xylamine($0.3{\mu}M$) on the PE-induced contractions were suppressed by N(G)-nitro-L-arginine(L-NNA), N(omega)-nitro-L-arginine methyl ester(L-NAME), aminoguanidine, dexamethasone, methylene blue, 1H-[1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one(ODQ), indomethacin, ryanodine, tetrabutylammonium(TBA), lidocaine, procaine and 0 mM extracellular $Na^+$, but not by 2-nitro-4-carboxyphenyl-n,n-diphenylcarbamate(NCDC), lithium, nifedipine, verapamil, 0 mM extracellular $Ca^{2+}$, glibenclamide and clotrimazole. These findings suggest that xylamine could act as a vasorelaxant and direct inhibitor of arterial contraction. This vasorelaxation involves an endothelial nitric oxide (NO)/cGMP (guanosine 3',5'-cyclic monophosphate) pathway or cyclooxygenase system, and an interference with $Ca^{2+}$ release, TBA-sensitive $Ca^{2+}$-activated $K^+$ channels and $Na^+$$ channels.

Mechanism underlying NO-induced apoptosis in human gingival fibroblasts

  • Hwang, In-Nam;Jeong, Yeon-Jin;Jung, Ji-Yeon;Lee, Jin-Ha;Kim, Kang-Moon;Kim, Won-Jae
    • International Journal of Oral Biology
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    • v.34 no.1
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    • pp.7-14
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    • 2009
  • Nitric oxide (NO) acts as an intracellular messenger at the physiological level but can be cytotoxic at high concentrations. The cells within periodontal tissues, such as gingival and periodontal fibroblasts, contain nitric oxide syntheses and produce high concentrations of NO when exposed to bacterial lipopolysaccharides and cytokines. However, the cellular mechanisms underlying NO-induced cytotoxicity in periodontal tissues are unclear at present. In our current study, we examined the NO-induced cytotoxic mechanisms in human gingival fibroblasts (HGF). Cell viability and the levels of reactive oxygen species (ROS) were determined using a MTT assay and a fluorescent spectrometer, respectively. The morphological changes in the cells were examined by Diff-Quick staining. Expression of the Bcl-2 family and Fas was determined by RT-PCR or western blotting. The activity of caspase-3, -8 and -9 was assessed using a spectrophotometer. Sodium nitroprusside (SNP), a NO donor, decreased the cell viability of the HGF cells in a dose- and time-dependent manner. SNP enhanced the production of ROS, which was ameliorated by NAC, a free radical scavenger. ODQ, a soluble guanylate cyclase inhibitor, did not block the SNP-induced decrease in cell viability. SNP also caused apoptotic morphological changes, including cell shrinkage, chromatin condensation, and DNA fragmentation. The expression of Bax, a member of the proapoptotic Bcl-2 family, was upregulated in the SNP-treated HGF cells, whereas the expression of Bcl-2, a member of the anti-apoptotic Bcl-2 family, was downregulated. SNP augmented the release of cytochrome c from the mitochondria into the cytosol and enhanced the activity of caspase-8, -9, and -3. SNP also upregulated Fas, a component of the death receptor assembly. These results suggest that NO induces apoptosis in human gingival fibroblast via ROS and the Bcl-2 family through both mitochondrial- and death receptor-mediated pathways. Our data also indicate that the cyclic GMP pathway is not involved in NO-induced apoptosis.

[$PGE_2$ Regulates Pacemaker Currents through $EP_2-Receptor$ in Cultured Interstitial Cells of Cajal from Murine Small Intestine

  • Choi, Seok;Cho, Kyung-Won;Reu, Jong-Hyun;Kim, Jun-Soo;Mun, Hyun-Sik;Kim, Myung-Young;Park, Kwang-Chul;Heo, Gwang-Sik;Chang, Sung-Jong;Yeum, Cheol-Ho;Yoon, Pyung-Jin;Jun, Jae-Yeoul
    • The Korean Journal of Physiology and Pharmacology
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    • v.8 no.3
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    • pp.153-159
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    • 2004
  • The interstitial cells of Cajal (ICCs) are the pacemaker cells in gastrointestinal tract and generate electrical rhythmicity in gastrointestinal muscles. Therefore, ICC may be modulated by endogenous agents such as neurotransmitter, hormones, and prostaglandins (PGs). In the present study, we investigated the effects of prostaglandins, especially $PGE_2$, on pacemaker currents in cultured ICCs from murine small intestine by using whole-cell patch clamp techniques. ICCs generated spontaneous slow waves under voltage-clamp conditions and showed a mean amplitude of $-452{\pm}39\;pA$ and frequency of $18{\pm}2$ cycles/min (n=6). Treatments of the cells with $PGE_2$ $(1\;{\mu}M)$ decreased both the frequency and amplitude of the pacemaker currents and increased the resting currents in the outward direction. $PGE_2$ had only inhibitory effects on pacemaker currents and this inhibitory effect was dose-dependent. For characterization of specific membrane EP receptor subtypes, involved in the effects of $PGE_2$ on pacemaker currents in ICCs, EP receptor agonists were used: Butaprost $(1\;{\mu}M)$, $EP_2$ receptor agonist, reduced the spontaneous inward current frequency and amplitude in cultured ICCs (n=5). However sulprostone $(1\;{\mu}M)$, a mixed $EP_1$ and $EP_3$ agonist, had no effects on the frequency, amplitude and resting currents of pacemaker currents (n=5). SQ-22536 (an inhibitor of adenylate cyclase; $100\;{\mu}M$) and ODQ (an inhibitor of guanylate cyclase; $100\;{\mu}M$) had no effects on $PGE_2$ actions of pacemaker currents. These observations indicate that $PGE_2$ alter directly the pacemaker currents in ICCs, and that the $PGE_2$ receptor subtypes involved are the $EP_2$ receptor, independent of cyclic AMP- and GMP-dependent pathway.