• Journal of Ginseng Research
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• v.40 no.3
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• pp.285-291
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• 2016

Background: Ginsenosides have been shown to exert beneficial pharmacological effects on the central nervous, cardiovascular, and endocrine systems. We sought to determine whether total ginsenosides (TG) inhibit monocrotaline (MCT)-induced pulmonary hypertension and to elucidate the underlying mechanism. Methods: MCT-intoxicated rats were treated with gradient doses of TG, with or without $N^G$-nitro-$\small{L}$-arginine methyl ester. The levels of molecules involving the regulation of nitric oxide and mitogen-activated protein kinase pathways were determined. Results: TG ameliorated MCT-induced pulmonary hypertension in a dose-dependent manner, as assessed by the right ventricular systolic pressure, the right ventricular hypertrophy index, and pulmonary arterial remodeling. Furthermore, TG increased the levels of pulmonary nitric oxide, endothelial nitric oxide synthase, and cyclic guanosine monophosphate. Lastly, TG increased mitogen-activated protein kinase phosphatase-1 expression and promoted the dephosphorylation of extracellular signal-regulated protein kinases 1/2, p38 mitogen-activated protein kinase, and c-Jun NH2-terminal kinase 1/2. Conclusion: TG attenuates MCT-induced pulmonary hypertension, which may involve in part the regulation of nitric oxide and mitogen-activated protein kinase pathways.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.1
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• pp.29-35
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• 2010

We have shown that myosin light chain kinase (MLCK) was required for the off-contraction in response to the electrical field stimulation (EFS) of feline esophageal smooth muscle. In this study, we investigated whether protein kinase C (PKC) may require the on-contraction in response to EFS using feline esophageal smooth muscle. The contractions were recorded using an isometric force transducer. On-contraction occurred in the presence of $N^G$-nitro-L-arginine methyl ester (L-NAME), suggesting that nitric oxide acts as an inhibitory mediator in smooth muscle. The excitatory composition of both contractions was cholinergic dependent which was blocked by tetrodotoxin or atropine. The on-contraction was abolished in $Ca^{2+}$-free buffer but reappeared in normal $Ca^{2+}$-containing buffer indicating that the contraction was $Ca^{2+}$ dependent. 4-aminopyridine (4-AP), voltage-dependent $K^+$ channel blocker, significantly enhanced on-contraction. Aluminum fluoride (a G-protein activator) increased on-contraction. Pertussis toxin (a $G_i$ inactivator) and C3 exoenzyme (a rhoA inactivator) significantly decreased on-contraction suggesting that Gi or rhoA protein may be related with $Ca^{2+}$ and $K^+$ channel. ML-9, a MLCK inhibitor, significantly inhibited on-contraction, and chelerythrine (PKC inhibitor) affected on the contraction. These results suggest that endogenous cholinergic contractions activated directly by low-frequency EFS may be mediated by $Ca^{2+}$, and G proteins, such as Gi and rhoA, which resulted in the activation of MLCK, and PKC to produce the contraction in feline distal esophageal smooth muscle.

• Korean Journal of Veterinary Research
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• v.46 no.4
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• pp.323-326
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• 2006

Suaeda (S.) asparagoides $M_{IQ}$, one of the halophyte groups, has been used as a folk remedy for digestive disturbances in Korea. However, its pharmacological activity on gastrointestinal motility has not been reported yet. In this study, the effects of this halophyte extracts with various solvent fractions (ethanol, hexane, chloroform, ethyl acetate, butanol, and water) on mice ileal spontaneous motility was examined. All solvent fractions at the concentration of $100{\mu}g/ml$ showed inhibitory actions on spontaneous motility of ileum with the potency order of water > 70% ethanol > hexane ${\gg}$ chloroform ${\geq}$ butanol ${\geq}$ ethyl acetate, respectively. In addition, the water fraction of extracts from S. asparagoides $M_{IQ}$ (WFSA) dose-dependently ($1-100{\mu}g/ml$) inhibited the amplitude of spontaneous phasic contraction and area under the contractile curve (AUC). The inhibitory effect of water fraction at the concentration of $10{\mu}g/ml$ was not affected by tetrodotoxin (TTX), $Na^+$ channel blocker ($1{\mu}M$), and $N^w$-nitro-L-arginine Methyl Ester (L-NAME), nitric oxide synthase inhibitor ($100{\mu}M$). However, cyclopiazonic acid (CPA, $10{\mu}M$), inhibitor of sarcoplasmic reticulum $Ca^{2+}$-ATPase, almost blocked the inhibitory effects of WFSA ($10{\mu}g/ml$) on the spontaneous phasic contraction of mouse ileum. But, CPA did not inhibit the lowering basal tone effects of WFSA. The result of this study showed that various extracts of S. asparagoides $M_{IQ}$ induce inhibitory effects on spontaneous contraction of mice ileal segments. More over, the polar solvent fractions were shown to be more potent than non-polar solvent fractions. The effects of S. asparagoides $M_{IQ}$ extracts are not mediated by nerve or nitric oxide. The inhibitory effects of WFSA at least partially mediated by sarcoplasmic reticulum $Ca^{2+}$-ATPase. However, further study is required to determine the exact pharmacological mechanisms of this halophyte on its gastrointestinal motility inhibitory effects.

• Archives of Pharmacal Research
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• v.24 no.1
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• pp.64-68
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• 2001

Endothelin-1 (ET-1 ), a novel and potent vasoconstrictor in blood vessel, is known to have some functions in the rat central nervous system (CNS), In order to investigate the central functions of ET-1 , ET-1 was administered to the periaqueductal gray area (PAC) of anesthetized rats to induce barrel rolling and increase the arterial blood pressure (ABP). ET-1 had a modulatory effect on central cardiovascular and behavioral control. The selective N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (3${u}m/ol/kg$, i.p.) blocked the ET-1 induced responses, and both the nitric oxide synthase (NOS) inhibitor L-NAME (N-nitro-L-arginine mIThyl-ester 1 nmol/rat) and the nitric oxide (NO) scavenger hemoglobin (15 nmol/rat) had similar effects in redtAcing the IT-1 (10 pmol/rat)-induced behavioral changes and ABP elevation. However, NO donor sodium nitroprusside (SNP 10${u}g$, 1${u}g/rat$) decreased the ET-1 induced ABP elevation, and recovered the ET-1 -induced barrel rolling effect that was reduced by MK-801. These results suggest that ET-1 might have neuromodulatory functions such as ABP elevation and barrel rolling induction in the PAG of the rats via the NMDA receptor and NO.

• 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 N^G-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.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.5
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• pp.435-440
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• 2015

This study aimed to investigate the effect of pituitary adenylate cyclase-activating peptide (PACAP) on the pacemaker activity of interstitial cells of Cajal (ICC) in mouse colon and to identify the underlying mechanisms of PACAP action. Spontaneous pacemaker activity of colonic ICC and the effects of PACAP were studied using electrophysiological recordings. Exogenously applied PACAP induced hyperpolarization of the cell membrane and inhibited pacemaker frequency in a dose-dependent manner (from 0.1 nM to 100 nM). To investigate cyclic AMP (cAMP) involvement in the effects of PACAP on ICC, SQ-22536 (an inhibitor of adenylate cyclase) and cell-permeable 8-bromo-cAMP were used. SQ-22536 decreased the frequency of pacemaker potentials, and cell-permeable 8-bromo-cAMP increased the frequency of pacemaker potentials. The effects of SQ-22536 on pacemaker potential frequency and membrane hyperpolarization were rescued by co-treatment with glibenclamide (an ATP-sensitive $K^+$ channel blocker). However, neither $N^G$-nitro-L-arginine methyl ester (L-NAME, a competitive inhibitor of NO synthase) nor 1H-[1,2,4]oxadiazolo[4,3-${\alpha}$]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) had any effect on PACAP-induced activity. In conclusion, this study describes the effects of PACAP on ICC in the mouse colon. PACAP inhibited the pacemaker activity of ICC by acting through ATP-sensitive $K^+$ channels. These results provide evidence of a physiological role for PACAP in regulating gastrointestinal (GI) motility through the modulation of ICC activity.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.3
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• pp.177-183
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• 2010

Tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthase (NOS) activity, is known to play important roles in modulating both NO and superoxide production during vascular diseases such as atherosclerosis. However, the role of BH4 in functions of vascular smooth muscle cells is not fully known. In this study, we tested the effects of BH4 and dihydrobiopterin (BH2), a BH4 precursor, on migration and proliferation in response to platelet-derived growth factor-BB (PDGF-BB) in rat aortic smooth muscle cells (RASMCs). Cell migration and proliferation were measured using a Boyden chamber and a 5-bromo-2'-deoxyuridine incorporation assay, respectively, and these results were confirmed with an ex vivo aortic sprout assay. Cell viability was examined by 2,3-bis [2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide assays. BH4 and BH2 decreased PDGF-BBinduced cell migration and proliferation in a dose-dependent manner. The inhibition of cell migration and proliferation by BH4 and BH2 was not affected by pretreatment with $N^G$-nitro-L-arginine methyl ester, a NOS inhibitor. Moreover, the sprout outgrowth formation of aortic rings induced by PDGF-BB was inhibited by BH4 and BH2. Cell viability was not inhibited by BH4 and BH2 treatment. The present results suggest that BH4 and BH2 may inhibit PDGF-stimulated RASMC migration and proliferation via the NOS-independent pathway. Therefore, BH4 and its derivative could be useful for the development of a candidate molecule with an NO-independent anti-atherosclerotic function.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.5
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• pp.425-430
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• 2014

This study was designed to examine the effects of histamine on gastric motility and its specific receptor in the circular smooth muscle of the human gastric corpus. Histamine mainly produced tonic relaxation in a concentration-dependent and reversible manner, although histamine enhanced contractility in a minor portion of tissues tested. Histamine-induced tonic relaxation was nerve-insensitive because pretreatment with nerve blockers cocktail (NBC) did not inhibit relaxation. Additionally, $K^+$ channel blockers, such as tetraethylammonium (TEA), apamin (APA), and glibenclamide (Glib), had no effect. However, $N^G$-nitro-L-arginine methyl ester (L-NAME) and 1H-(1,2,4)oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), did inhibit histamine-induced tonic relaxation. In particular, histamine-induced tonic relaxation was converted to tonic contraction by pretreatment with L-NAME. Ranitidine, the $H_2$ receptor blocker, inhibited histamine-induced tonic relaxation. These findings suggest that histamine produced relaxation in circular smooth muscle of human gastric smooth muscle through $H_2$ receptor and NO/sGC pathways.

• Tuberculosis and Respiratory Diseases
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• v.47 no.2
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• pp.172-183
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• 1999

Background: Nitric oxide is a short-lived effector molecule derived from L-arginine by the nitric oxide synthase(NOS). Nitric oxide plays a role in a number of physiologic and pathophysiologic functions including host defense, edema formation, and regulation of smooth muscle tone. Some kinds of cells including macrophage are known to produce large quantities of nitric oxide in response to inflammatory stimuli such as interleukin-$1\beta$(IL-$1\beta$), tumor necrosis factor-$\alpha$(TNF-$\alpha$), interferon-$\gamma$(IFN-$\gamma$) and lipopolysaccharide(LPS). Reactive oxygen species are also known to be important in the pathogenesis of acute cell and tissue injury such as acute lung injury model Methods: Using the RA W264.7 cells, we have examined the ability of oxidant hydrogen peroxide($H_2O_2$) to stimulate nitric oxide production and inducible NOS mRNA expression. Also, we have examined the effects of NOS inhibitors and antioxidants on $H_2O_2$ induced nitric oxide production. Results: Stimulation of RAW264.7 cells with combinations of 100 ng/ml IL-$1\beta$, 100 ng/ml TNF-$\alpha$, and 100 U/ml IFN-$\gamma$ or 100 U/ml IFN-$\gamma$ and $1{\mu}g/ml$ LPS induced the synthesis of nitric oxide as measured by the oxidation products nitrite($NO_2^-$) and nitrate($NO_3^-$). Addition of $250 {\mu}M-2$ mM $H_2O_2$ to the cytokines significantly augmented the synthesis of $NO_2^-$ and $NO_3^-$(p<0.05). When cells were incubated with increasing concentrations of $H_2O_2$ in the presence of IL-$1\beta$, TNF-$\alpha$ and IFN-$\gamma$ at constant level, the synthesis of $NO_2^-$ and $NO_3^-$ was dose-dependently increased(p<0.05). $N^G$-nitro-L-arginine methyl ester(L-NAME), dose dependently, significantly inhibited the formation of $NO_2^-$ and $NO_3^-$ in cells stimulated with LPS, IFN-$\gamma$ and $H_2O_2$ at constant level(p<0.05). Catalase significantly inhibited the $H_2O_2$-induced augmentation of cytokine-induced $NO_2^-$ and $NO_3^-$ formation(p<0.05). But, boiled catalase did not produce a significant inhibition in comparison with the native enzyme. Another antioxidant 2-mercaptoethanol and orthophenanthroline dose-dependently suppressed $NO_2^-$ and $NO_3^-$ synthesis(p<0.05). Northern blotting demonstrated that H:02 synergistically stimulated the cytokine-induced iNOS mRNA expression in RA W264.7. Conclusion: These results suggest that $H_2O_2$ contributes to inflammatory process by augmenting the iNOS expression and nitric oxide synthesis induced by cytokines.

• The Journal of Internal Korean Medicine
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• v.27 no.1
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• pp.276-287
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• 2006

Background & Objective : The herbal medicine Sojukgunbihwan granule has been used for the treatment of functional dyspepsia, generally categorized as a gastric dysmotility disease. However, its mechanisms are not yet well known. Therefore, the effects of Sojukgunbihwan granules on gastric motility in rats was investigated. Methods : The myoelectrical activity of the gastric smooth muscle was recorded by a bipolar electrode placed at the gastric antrum of rats. The contractile waves were measured for 30 minutes before and after intragastric administration of each solution(normal saline, Pyungwisan 40mg/kg, Sojukgunbihwan granules 60mg/kg) and expressed as the motility index. Gastric emptying was measured by the number of glass beads expelled from the stomach(containing one hundred 1mm glass beads) within an hour after glass beads and test drugs(normal saline, Pyungwisan 40mg/kg, Pyungwisan 120mg/kg, Sojukgunbihwan granules 60mg/kg, Sojukgunbihwan granules 180mg/kg) were administered. In another series of experiments to evaluate the mechanisms of Sojukgunbihwan granules under delayed conditions, the rats were treated with atropine sulfate(1 mg/kg, s.c.), cisplatin(10mg/kg, i.p.), and NAME($N^G$-nitro-L-arginine methyl ester, 75mg/kg, s.c.) respectively. Results : Intragastric administration of Sojukgunbihwan granules increased the myoelectrical activity significantly, gastric motility index rose 25%, and gastric emptying of glass beads was significantly enhanced over a period of 60minutes. Under the delayed gastric emptying induced by atropine sulfate, cisplatin, and NAME, Sojukgunbihwan granules aggravated gastric emptying in the atropine sulfate($5.71{\pm}3.45\;vs\;3.71{\pm}4.42$) and cisplatin($13.86{\pm}3.53\;vs\;5.14{\pm}5.05$, p<0.01) treated groups, but enhanced gastric emptying in the NAME treated group($5.00{\pm}3.21\;vs\;11.71{\pm}5.65$, p<0.05). Conclusions : Results suggest that Sojukgunbihwan granules stimulate gastric motility through cholinergic and 5-hydroxytryptamine 3 receptors. Results are indicative of Sojukgunbihwan as an especially effective remedy in dysmotility-like functional dyspepsia with impaired reservoir functions such as gastric adaptive relaxation.