• Molecules and Cells
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• 제22권1호
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• pp.44-50
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• 2006

We investigated the possible role of p38 MAPK and $ET_B$ receptors in ET-1 induction of cyclooxygenase-2 (COX-2) and prostaglandin $E_2$ ($PGE_2$) in cultured feline esophageal smooth muscle cells (ESMC). Confluent layers of ESMC were stimulated with 10 nM ET-1 and expression of COX-1 and COX-2, involvement of receptors, and activation of p38 MAPK, were examined by Western blot analysis. Levels of $PGE_2$ induced by ET-1 were measured by Elisa. Using $ET_A$and $ET_B$ antagonists (BQ-123 and BQ-788, respectively), the contribution of the ET receptors to COX-1 and COX-2 expression induced by ET-1 was determined. Western blot analysis revealed that treatment of ESMC with ET-1 resulted in transient expression of COX-2 and activation of p38 MAPK. Activation of p38 MAPK was maximal after 1 h. SB202190, a p38 MAPK inhibitor, reduced expression of COX-2, but not COX-1. ET-1-induced release of $PGE_2$ was also blocked by SB202190. COX-2 expression was upregulated only via the $ET_B$ receptor, and COX-1 expression was not affected by either antagonist. Taken together, our data suggest that ET-1 causes p38 MAPK-dependent expression of COX-2 by interacting with $ET_B$ receptors on ESMC.

• The Korean Journal of Physiology and Pharmacology
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• 제10권6호
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• pp.343-347
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• 2006

The present study was designed to investigate the effects renin-angiotensin-aldosterone system (RAAS), endothelin (ET) and local natriuretic peptide (NP) system for glomerulopathy induced in the experimental bilateral ureteral obstructive rats. Sprague-Dawley male rats ($200{\sim}220g$ body weight) were bilaterally obstructed by ligation of the proximal ureters for 24 hours. Control rats were treated in the same ways, except that no ligature was made. The glomeruli were isolated from cortex by graded sieve methods, and the mRNA expressions of local renin-angiotensin system (RAS), aldosterone synthase (CYP11B2), endothelin-1 (ET-1) and NP system were determined by real-time polymerase chain reaction. Following the bilateral ureteral obstruction, the mRNA expressions of renin, angiotensin converting enzyme 1 as well as ET-1 were increased, while that of angiotensin converting enzyme 2 was not changed. The expressions of CYP11B2 and angiotensin II receptors were not changed. C-type natriuretic peptide (CNP) expression was increased, while its receptors (natriuretic peptide receptor-B) were not changed. We suggest that the upregulation of local RAS and ET playa role in the progressive glomerular injury, and that the enhanced CNP activity also plays a compensatory role in obstructive uropathy in the glomerulus.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.192-192
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• 1996

Endothelin has $ET_{A}$ type and $ET_{B}$ type receptors, and it has been thought that ET-1 proves vasoconstriction effect via $ET_{A}$ receptor and vasodilation via $ET_{B}$ receptor. Recently, it has been reported that $ET_{B}$ receptor is also related to the vaso-constriction. Bosentan is a $ET_{A+B}$ receptor antagonist, and proves it's effect on trauma and ischemia. We already announced that the level of Endothelin-1 increase in the brain and spinal cord of EAE-induced lewis rat and showed the origin of ET-1 is activated macrophages. Intracisternal injection of Bosentan, $ET_{A+B}$ receptor antagonist, (300nmol/body) was done for observing the role of endothelin-1 on the pathogenesis of EAE. Bosentan ameliorated the severity of clinical score of EAE and decreased the histologically observed inflammatory region. The blocking effect on the progression of EAE model suggests that Bosentan is a physiological antagonist in terms of development of the sign of multiple sclerosis.

• Animal cells and systems
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• 제4권1호
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• pp.63-70
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• 2000

The distribution of receptor subtypes for endothelin (ET) in the kidney of the freshwater turtle, Amyda japonica, was examined by quantitative in vitro receptor autoradiography using iodinatd mammalian type ET-1 ($^125$/I-ET-1)as a radiolabeled ligand. Specific $^125$/I-ET-1 bindings were localized to renal tubules, renal arteries and ureter with binding densities of 111.21 $\pm$ 19.14, 182.13$\pm$10.57 and 219.46$\pm$12.83 amol/$mm^2$. respectively. Binding dissociation constants in renal tubules, renal arteries and ureter were 1.05 $\pm$ 0.63, 2.03 $\pm$0.56 and 1.70$\pm$0.47nM, respectively. Receptor subtypes for ET in the kidney were characterized by competition with BQ 123 and BQ 788 as specific antagonists for ET receptors, type A (ET$_A$ ), and type B (ET$_B$) subtypes, respectively. Specific $^125$/I-ET-1 bindings in renal arteries and ureter were potently inhibited by BQ 123 in a dose-dependent manner, whereas BQ 788 was not in competing for specific $^125$/I-ET-1 bindings in this structure. However, specific $^125$/I-ET-1 bindings in renal tubules were inhibited more potently by BQ 788. Therefore, these results indicate that specific ET receptors are localized in renal tubules, renal arteries and the ureter of the freshwater turtle. Results also suggest that the predominant ET receptor subtypes are like the ETA receptor in renal arteries and ureter, and like the ET/$_A$ receptor in the renal tubule.

• Archives of Pharmacal Research
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• 제27권1호
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• pp.111-117
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• 2004

Hepatic microcirculatory failure is a major component of reperfusion injury in the liver. Recent data provided some evidence that endothelium-derived vasoconstrictors and vasodilators may be functionally important to the control of the total hepatic blood flow under these conditions of circulatory failure. Since Kupffer cells provide signals that regulate the hepatic response in ischemia/reperfusion (I/R), the aim of this study was to investigate the role of Kupffer cells in the I/R-induced imbalance of vasoregulatory gene expression. Rats were subjected to 60 min hepatic ischemia, followed by 5 h of reperfusion. The Kupffer cells were inactivated by gadolinium chloride ($GdCl_3$, 7.5 mg/kg body weight, intravenously) 1 day prior to ischemia. Liver samples were obtained 5 hrs after reperfusion for RT-PCR analysis of the mRNA for genes of interest: endothelin-1 (ET-1), its receptors $ET_A and ET_B$, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1). ET-1 mRNA expression was increased by I/R. mRNA levels for $ET_A$ receptors showed no change, whereas $ET_B$ receptor transcripts increased in the I/R group. The increases in ET-1 and $ET_B$ mRNA were not prevented by the $GdCI_3$ pretreatment. The mRNA levels for iNOS and eNOS significantly increased within the I/R group with no significant difference between the I/R group and the $GdCl_3$-treated I/R group. HO-1 mRNA expression significantly increased in the I/R group and this increase was attenuated by $GdCI_3$. In conclusion, we have demonstrated that an imbalance in hepatic vasoregulatory gene expression occurs during I/R. Our findings suggest that the activation of Kupffer cells is not required for I/R-induced hepatic microvascular dysfunction.

• Molecules and Cells
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• 제23권3호
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• pp.331-339
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• 2007

It has been suggested that the structure and function of nuclear receptors are evolutionally conserved. Here, we compare the molecular functions of the nile tilapia (Oreochromis niloticus) small heterodimer partner (nSHP/NR0B2) and the Dosage-sensitive sex reversal AHC critical region on X chromosome gene 1 (nDAX-1/NR0B1) with those of human SHP and DAX-1 (hSHP and hDAX-1, respectively). We found that, upon transient cotransfection of human cells, nDAX-1 repressed the activity of tilapia SF-1 (nSF-1) but not that of human SF-1, although the physical interaction with human SF-1 was retained. Similarly, nSHP repressed the activity of nSF-1, whereas hSHP did not, pointing to divergent evolution of SHP/SF-1 in fish and human. We thus propose that the repressive functions of SHP and DAX-1 have been conserved in fish and mammals although with different transcriptional targets and mechanisms. These differences provide new insights into the physiological diversification of atypical orphan nuclear receptors during vertebrate evolution.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.73-86
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• 2003

Endothelins secreted from keratinocytes are intrinsic madiators for human melanocytes in UVB-induced pigmentation. Antimelanogenic ingredient, 1,2-Ο-diferulylglycerol(SM709) isolated from bamboo extract inhibited the melanin synthesis of Bl6F10 melanoma cells by 62%. To understand the cellular mechanism of antimelanogenic activity of SM709 in human melanocytes, the effects of SM709 on the ET-l-induced $Ca^{2+}$ mobilization were investigated. ET-l receptors in human melanocytes were characterized by using specific antagonist and found that ET-l increased intracellular $Ca^{2+}$ by activating ET-B receptor. SM709 completely blocked the ET-l-induced intracellular $Ca^{2+}$ increase and its inhibitory effect showed dose- and time- dependent manners. To investigate the role of SM709 on intracellular $Ca^{2+}$ store, when the $Ca^{2+}$ store was partially depleted by thapsigargin; a specific inhibitor of ER-type $Ca^{2+}$-ATPase, caffeine-induced $Ca^{2+}$ mobilization did not changed in the presence or absence of SM709, suggesting that SM709 has no effect on the $Ca^{2+}$ store. It is known that LPA receptor and P$_2$ receptor are linked to InsP$_3$ second messenger system. When these receptors in melanocytes were activated by LPA and ATP, the intracellular $Ca^{2+}$ signaling was observed even in the presence of SM709. From the above results, it can be suggested that SM709 has an antimelanogenic activity by antagonizing the ET-B receptor, resulting in subsequent intracellular $Ca^{2+}$ signaling, in UV induced pigmentation.nduced pigmentation.

• Biomolecules & Therapeutics
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• 제12권2호
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• pp.62-67
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• 2004

Trauma remains one of the important sources leading to systemic inflammatory response anti sub-sequent multiple organ failure. Although hepatic microvascular dysfunction occurs during trauma, the mechanism responsible remains unclear. The aim of this study was to investigate the effect of trauma on hepatic vascular stress gene expression. Femur fracture (EFx) was induced by torsion to the femur at midshaft. Liver samples were taken for RT-PCR analysis of mRNA for gtenes of interest: endothelin-1 (ET-1), its receptors $ET_A$ and $ET_B$, nitric oxide synthases (iNOS and eNOS), cyclooxygenase-2 (COX-2), heme oxygenase-1 (HO-1), and tumor necrosis tactor-${\alpha}$ (TNF-${\alpha}$). The expression of ET-1 mRNA was significantly increased by FFx. Expression of mRNA in FFx group showed no change in $ET_A$, $ET_B$, iNOS and HO-1 and showed a slight increase of 2.2-fold and 2.7-fold for eNOS tll1d COX-2, respectively. The level of TNF-${\alpha}$ mRNA significantly increased in FFx group. In conclusion, mild trauma alone causes little change in expression of vasoactive mediators.

• The Korean Journal of Physiology and Pharmacology
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• 제9권5호
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• pp.305-314
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• 2005

Diabetes mellitus is associated with vascular complications, including an impairment of vascular function and alterations in the reactivity of blood vessels to vasoactive substances in various vasculature. In the present study, the authors have observed endothelin-B ($ET_B$) receptor agonist-induced relaxation in precontracted mesenteric arterial segments from streptozotocin (STZ)-induced diabetic rats, which was not shown from control rats or in other arterial segments from diabetic rats. Accordingly, the goal of this study was to investigate in what way STZ-induced diabetes altered reactivity of the mesenteric arterial bed and to examine the causal relaxation, if any, between this $ET_B$ receptor-mediated relaxation and endothelial paracrine function, especially nitric oxide (NO) production. The relaxation induced by $ET_B$ agonists was not observed in mesenteric arteries without endothelium. The relaxation to $ET_B$ agonists was completely abolished by pretreatment with BQ788, but not by BQ610. $N_{\omega}-nitro-L-arginine$ methyl ester and soluble guanylate cyclase inhibitors, methylene blue or LY83583 significantly attenuated the relaxant responses to $ET_B$ agonists, respectively. When the expression of eNOS and iNOS was evaluated on agarose gel stained with ethidium bromide, the expression of eNOS mRNA in diabetic rats was significantly decreased, but the expression of iNOS was increased compared with control rats. Furthermore, the iNOS-like immunostaining was densely detected in the endothelium and slightly in the arterial smooth muscle of diabetic rats, but not in control rats. These observations suggest that $ET_B$ receptor may not play a role in maintaining mesenteric vascular tone in normal situation. However, the alterations in $ET_B$ receptor sensitivity were found in diabetic rats and lead to the $ET_B$ agonist-induced vasorelaxation, which is closely related to NO production. In the state of increased vascular resistance of diabetic mesenteric vascular bed, enhanced NO production by activation of iNOS could lead to compensatory vasorelaxation to modulate adequate perfusion pressure to splanchnic area.

• Biomolecules & Therapeutics
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• 제16권4호
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• pp.306-311
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• 2008

Although hepatic microcirculatory dysfunction occurs during endotoxemia, the mechanism responsible for this remains unclear. Since Kupffer cells provide signals that regulate hepatic response in inflammation, this study was designed to investigate the role of Kupffer cells in the imbalance in the expression of vasoactive mediators. Endotoxemia was induced by intraperitoneal E. coli endotoxin (LPS, 1 mg/kg body weight). Kupffer cells were inactivated with gadolinium chloride ($GdCl_3$, 7.5 mg/kg body weight, intravenously) 2 days prior to LPS exposure. Liver samples were taken 6 h following LPS exposure for RT-PCR analysis of mRNA for genes of interest: endothelin (ET-1), its receptors $ET_A$ and $ET_B$, inducible nitric oxide synthase (iNOS), heme oxygenase (HO-1), and tumor necrosis factor-$\alpha$ (TNF-$\alpha$). mRNA levels for iNOS and TNF-$\alpha$ were significantly increased 31.8-fold and 26.7-fold in LPS-treated animals, respectively. This increase was markedly attenuated by $GdCl_3$, HO-1 expression significantly increased in LPS-treated animals, with no significant difference between saline and $GdCl_3$ groups. ET-1 was increased by LPS. mRNA levels for $ET_A$ receptor showed no change, whereas $ET_B$ transcripts increased in LPS-treated animals. The increase in $ET_B$ transcripts was potentiated by $GdCl_3$. We conclude that activation of Kupffer cells plays an important role in the imbalanced hepatic vasoregulatory gene expression induced by endotoxin.