• 대한약리학회지
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• 제28권1호
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• pp.61-74
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• 1992

마취가토에서 혈압유지에 중요한 역할을 하고 있는 교감신경계, renin-angiotensin계, vasopressin계를 차단하였을때의 혈압자체의 변동과 norepinephrine (NE), angiotensin II (AII) 및 vasopressin (VP)의 승압효과의 변동을 조사하였다. 교감신경계와 renin-angiotensin계의 차단에는 각각 교감신경절 차단약인 chlorisondamine (CS)과 pirenzepine (PZ), angiotensin 변환효소억제약인 enalapril (ENAL)를 사용하였다. VP계의 차단에는 혈장 VP농도를 하강시킴이 알려져 있는 kappa opioid 수용체의 작용약인 bremazocine (BREM)을 사용하였다. CS (0.4mg/kg), ENAL (2mg/kg), BREM (0.25mg/kg)은 각각 비슷한 정도의 저혈압상태를 일으켰다. BREM에 의한 저혈압은 VP와 같은 효과를 가진 합성약인 desmopressin으로 유의하게 길항되었으며 BREM에 의한 저혈압이 적어도 일부 혈장 VP농도의 하강과 관계있음을 시사하였다. CS는 ENAL 또는 BREM으로 하강된 혈압을, ENAL은 CS 또는 BREM으로 하강된 혈압을, BREM은 CS 또는 ENAL로 하강된 혈압을, 더욱 하강시켰다. CS, PZ 그리고 ENAL 또는 CS, PZ 그리고 BREM에 의한 저혈압은 CS이외의 세약물에 의한 저혈압보다 심하였다. CS는 NE에 의한 승압효과 뿐만아니라 AII와 VP의 승압효과도 강화시켰다. AII의 승압효과는 또 ENAL과 BREM으로도 증대되었다. VP의 승압효과는 BREM으로도 강화되었다. ${\alpha}$-수용체의 길항약인 phentolamine과 phenoxybenzamine은 AII와 VP승압효과를 강화시켰다. 3승압계 차단이 혈압자체에 미치는 실험결과는 3계가 모두 혈압조절에 관여하고 그 중에서도 교감신경계가 가장 큰 역할을 하고 있음을 가리키고 있다. 한 승압계의 차단하에서, 그 계의 승압 hormone 뿐만아니라 다른 계의 승압 hormone의 승압효과도 증대됨은 이 3승압계가 긴밀한 상호작용을 하고 있는 증거이다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권5호
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• pp.565-572
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• 1997

In the freshly isolated rat nephron, the effect of endothelin-1, -2 and -3 (ET-1, -2 and -3) on cytosolic free calcium concentration ($[Ca^{2+}]_i$) was determined using the fluorescent indicator Fura-2/AM. $[Ca^{2+}]_i$ increase was investigated in 9 parts of the single nephron including glomerulus (Glm), $S_1,\;S_2,\;S_3$, cortical and medullary thick ascending limb and cortical (CCT) and outer medullary collecting tubule (OMCT). Endothelins increased $[Ca^{2+}]_i$ in Glm (ET-1; $127{\pm}17%$, ET-2; $93{\pm}5%$, ET-3; $169{\pm}17%$), CCT (ET-1; $30{\pm}6%$, ET-2; $38{\pm}19%$, ET-3; $158{\pm}18%$) and OMCT (ET-1; $197{\pm}11%$, ET-2; $195{\pm}11%$, ET-3; $215{\pm}37%$) at 10-7 M. In OMCT, ET-1 and ET-2 increased $[Ca^{2+}]_i$ in a dose-dependent manner ($10^{-10}{\sim}10^{-6}$ M). To the contrary, ET-3-induced $[Ca^{2+}]_i$ rise was begun from $10^{-12}$ M. BQ-123Na, an antagonist of ETA receptor, at $10^{-4}$ M inhibited about 30% of $[Ca^{2+}]_i$ rise induced by ET-1 and -3. Binding experiments using $[^{125}I]ET-3$ showed the existence of $ET_B$ receptor in OMCT. This binding was replaced by ET-1, ET-2 or ET-3 by the almost same degree but not by angiotensin II or vasopressin.

• The Korean Journal of Physiology and Pharmacology
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• 제17권1호
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• pp.99-109
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• 2013

The aim of this study was to determine whether fimasartan, a newly developed $AT_1$ receptor blocker, can affect the CA release in the isolated perfused model of the adrenal medulla of spontaneously hypertensive rats (SHRs). Fimasartan (5~50 ${\mu}M$) perfused into an adrenal vein for 90 min produced dose- and time-dependently inhibited the CA secretory responses evoked by ACh (5.32 mM), high $K^+$ (56 mM, a direct membrane depolarizer), DMPP (100 ${\mu}M$) and McN-A-343 (100 ${\mu}M$). Fimasartan failed to affect basal CA output. Furthermore, in adrenal glands loaded with fimasartan (15 ${\mu}M$), the CA secretory responses evoked by Bay-K-8644 (10 ${\mu}M$, an activator of L-type $Ca^{2+}$ channels), cyclopiazonic acid (10 ${\mu}M$, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase), and veratridine (100 ${\mu}M$, an activator of $Na^+$ channels) as well as by angiotensin II (Ang II, 100 nM), were markedly inhibited. In simultaneous presence of fimasartan (15 ${\mu}M$) and L-NAME (30 ${\mu}M$, an inhibitor of NO synthase), the CA secretory responses evoked by ACh, high $K^+$, DMPP, Ang II, Bay-K-8644, and veratridine was not affected in comparison of data obtained from treatment with fimasartan (15 ${\mu}M$) alone. Also there was no difference in NO release between before and after treatment with fimasartan (15 ${\mu}M$). Collectively, these experimental results suggest that fimasartan inhibits the CA secretion evoked by Ang II, and cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by membrane depolarization from the rat adrenal medulla. It seems that this inhibitory effect of fimasartan may be mediated by blocking the influx of both $Na^+$ and $Ca^{2+}$ through their ion channels into the rat adrenomedullary chromaffin cells as well as by inhibiting the $Ca^{2+}$ release from the cytoplasmic calcium store, which is relevant to $AT_1$ receptor blockade without NO release.

• Journal of Yeungnam Medical Science
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• 제36권1호
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• pp.26-35
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• 2019

Background: Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice. Methods: Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase ${\alpha}$ ($G6Pase-{\alpha}$), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ${\zeta}$ ($PKC{\zeta}$) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice. Results: Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a $40{\mu}M$ concentration without a change in $G6Pase-{\alpha}$ expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 ($p-IRS-1-Ser^{302}$) and decreased $p-IRS-1-Tyr^{632}$ dose-dependently. Telmisartan dose-dependently increased $p-PKC{\zeta}-Thr^{410}$ which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative $PKC{\zeta}$ significantly attenuated telmisartan-induced HGP and $p-IRS-1-Ser^{302}$ and -inhibited $p-IRS-1-Tyr^{632}$. Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor ${\gamma}$ ($PPAR{\gamma}$) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased $p-IRS-1-Ser^{302}$ and decreased $p-IRS-1-Tyr^{632}$, which was accompanied by an increase in $p-PKC{\zeta}-Thr^{410}$. Conclusion: These results suggest that telmisartan increases HGP by inducing $p-PKC{\zeta}-Thr^{410}$ that increases $p-IRS-1-Ser^{302}$ and decreases $p-IRS-1-Tyr^{632}$ in a $PPAR{\gamma}$-independent manner

• The Korean Journal of Physiology and Pharmacology
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• 제14권4호
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• pp.241-248
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• 2010

The present sutdy aimed to determine whether olmesartan, an angiotensin II (Ang II) type 1 ($AT_1$) receptor blocker, can influence the CA release from the isolated perfused model of the rat adrenal medulla. Olmesartan ($5{\sim}50{\mu}M$) perfused into an adrenal vein for 90 min produced dose- and time-dependent inhibition of the CA secretory responses evoked by ACh (5.32 mM), high $K^+$ (56 mM, a direct membrane-depolarizer), DMPP (100 ${\mu}M$) and McN-A-343 (100 ${\mu}M$). Olmesartan did not affect basal CA secretion. Also, in adrenal glands loaded with olmesartan (15 ${\mu}M$), the CA secretory responses evoked by Bay-K-8644 (10 ${\mu}M$, an activator of voltage-dependent L-type $Ca^{2+}$ channels), cyclopiazonic acid (10 ${\mu}M$, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase), veratridine (100 ${\mu}M$, an activator of voltage-dependent $Na^+$ channels), and Ang II (100 nM) were markedly inhibited. However, at high concentrations ($150{\sim}300{\mu}M$), olmesartan rather enhanced the ACh-evoked CA secretion. Taken together, these results show that olmesartan at low concentrations inhibits the CA secretion evoked by cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by direct membrane depolarization from the rat adrenal medulla, but at high concentrations it rather potentiates the ACh-evoked CA secretion. It seems that olmesartan has a dual action, acting as both agonist and antagonist at nicotinic receptors of the isolated perfused rat adrenal medulla, which might be dependent on the concentration. It is also thought that this inhibitory effect of olmesartan may be mediated by blocking the influx of both $Na^+$ and $Ca^{2+}$ into the rat adrenomedullary chromaffin cells as well as by inhibiting the $Ca^{2+}$ release from the cytoplasmic calcium store, which is thought to be relevant to the $AT_1$ receptor blockade, in addition to its enhancement on the CA secreton.

• 대한한방내과학회지
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• 제29권4호
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• pp.1100-1114
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• 2008

The aim of the study was to investigate recovery effects of Rehmannia, which has been used clinically for chronic renal failure therapy. Mice had 5/6 nephrectomy to induce chronic renal failure. The results were as follows: 1. The protein amount in urine per 24hrs of the Rehmannia-treated group was significantly reduced compared to the control. 2. The albumin amount in the blood of the Rehmannia-treated group significantly increased compared to the control. The creatinine. total-cholesterol, LDL-cholesterol and triglyceride levels in serum of the Rehmannia-treated group as compared to the control were significantly inhibited. 3. The structural change in kidney of the Rehrnannia-treated group was significantly inhibited compared to the control. 4. The factor (macrophage/monocyte antigen (ED-1), type IV collagen and angiotensin II type 1 ($AT_1$) receptor) of the Rehmanala-treated group was significantly inhibited compared to the control, which induced the structural change in kidneys. The above results suggest that Rehmannia partially improved kidney function.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1995년도 춘계학술대회
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• pp.90-90
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• 1995

The Influence of age on the endothelial modulation of angiotensin II (AII)-induced contractile response was investigated in isolated aortic rings of rats ranging in age from 0.7 to 20 months. Hemoglobin and L-NAME were used to examine whether age-related changes in the EDRF-releasing system were involved in endothelial modulation of All-induced contraction in rat aorta. In all five age groups (0.7, 1.5, 3, 6, 20 months), hemoglobin (10 ${\mu}$M) significantly enhanced All-induced contractile response only in aorta with endothelium intact. L-NAME (10 ${\mu}$M) Produced a significant enhancement in All responses in endothelium-intact aortas from rats aged 0.7 and 1.5 months, but it had no effect in aortas from older rats aged 6 and 20 months. Indomethacin (10 ${\mu}$M) did not affect All-induced contractile responses in both endothelium intact and removed aortas from rats at the age of 0.7 to 20 months. Hemoglobin (10 ${\mu}$M) abolished acetylcholine-induced relaxation response in aortas from young and old rats. L-NAME completely abolished the relaxation in aortas from young (0.7 and 1.5 months), but incompletely in aortas from older (6 and 20 months) rats. The sensitivity of endothelium-dependent relaxation to A23187 increased with age between ages of 0.7 and 6 months, with no further increase noted up to 20 months of age. These results suggest that endothelial modulation of AII-induced contraction in rat aorta might involve age-related alteration in EDRF-releasing system, probably via post-receptor mechanism.

• 대한한방내과학회지
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• 제35권4호
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• pp.519-531
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• 2014

Objectives: Diabetic nephropathy is the most common cause of end stage renal disease. Transforming growth factor (TGF)-${\beta}1$, type IV collagen, advanced glycation end-products (AGEs), and angiotensin II type 1 receptor (AT1) are the main factors of diabetic nephropathy. We investigated the effects of Prunus on renal function and histopathological changes of diabetic nephropathy rat model induced by unilateral nephrectomy and streptozotocin. Methods: Diabetes was induced in male Sprague-Dawley rats ($290{\pm}10g$) by injecting streptozotocin (55 mg/kg) into the tail vein after unilateral nephrectomy. Rats were divided into 3 groups (n=6): normal, control, and Prunus. After 8 weeks of oral administration of Prunus extract on the Prunus group from 3 days after streptozotocin injection, we checked weight, 24 hrs urine, blood biochemistry and renal tissue to evaluate renal function and histopathological changes by examining parameters including albuminuria, BUN, creatinine, cholesterol, low density lipoprotein (LDL), triglyceride, TGF-${\beta}1$, type IV collagen, AGEs, and AT1. We also measured mRNA expression of TGF-${\beta}1$, type IV collagen, AGEs, and AT1 by Real Time polymerase chain reaction (RT-PCR). Results: Prunus decreased the amount of 24 hrs proteinuria, and inhibited histopathological changes of diabetic nephropathy including the expression and accumulation of TGF-${\beta}1$, type IV collagen and AGEs which could promote development of diabetic nephropathy. Prunus also inhibited mRNA expression of TGF-${\beta}1$, type IV collagen. Conclusions: These findings suggest that Prunus might protect the renal function and inhibit the development of renal injury by regulating factors including TGF-${\beta}1$, type IV collagen, AGEs, except AT1, so Prunus can be used for diabetic patients to prevent the progression of diabetic nephropathy.

• Clinical and Experimental Pediatrics
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• 제62권3호
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• pp.95-101
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• 2019

Purpose: Increased apoptosis was recently found in the hypertrophied left ventricle of spontaneously hypertensive rats (SHRs). Although the available evidence suggests that apoptosis can be induced in cardiac cells by various insults including pressure overload, cardiac apoptosis appears to result from an exaggerated local production of angiotensin in adult SHRs. Altered expressions of Bcl associated X (Bax), Bcl-2, chemokine receptor (CCR)-2, monocyte chemoattractant protein (MCP)-1, transforming growth factor $(TGF)-{\beta}1$, phosphorylated extracellular signal-regulated kinases (PERK), and connexin 43 proteins, and kallikrein mRNA were investigated to explore the effects of losartan on the SHR model. Methods: Twelve-week-old male rats were grouped as follows: control (C), SHR (hypertension: H), and losartan (L; SHRs were treated with losartan [10 mg/kg/day] for 5 weeks). Western blot and reverse transcription polymerase chain reaction assays were performed. Results: Expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, PERK, and connexin 43 proteins, and kallikrein mRNA was significantly increased in the H group compared to that in the C group at weeks 3 and 5. Expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, and connexin 43 proteins and kallikrein mRNA was significantly decreased after losartan treatment at week 5. PERK protein expression was significantly decreased after losartan treatment at weeks 3 and 5. Bcl-2 protein expression was significantly decreased in the H group compared to that in the C group at weeks 3 and 5. Conclusion: Losartan treatment reduced expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, PERK, and connexin 43 proteins, and kallikrein mRNA in SHRs, along with decreased inflammation and apoptosis.

• Mass Spectrometry Letters
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• 제12권2호
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• pp.31-40
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• 2021

Probable human carcinogenic compounds nitrosamines, have been detected as by-product impurities in sartan pharmaceuticals in recent years which has drawn worries for medication safety. To provide a sensitive and effective method for the quality control of sartan pharmaceuticals, this study established a feasible gas chromatography-tandem mass spectrometry (GC-MS/MS) method for simultaneous determination of 13 nitrosamines. The target analytes were separated on a DB-WAX Ultra Inert column (30 m × 0.25 mm; i.d., 0.25 ㎛) and were then subjected to electron impact ionization in multiple reaction monitoring mode. The established method was validated and further employed to analyze authentic samples. Limits of detection (LODs) and limits of quantification (LOQs) of the 13 nitrosamines were 15-250 ng/g and 50-250 ng/g, respectively, which also exhibited intra-day and inter-day accuracies of 91.4-104.8%, thereby satisfying validation criteria. Five nitrosamines, viz., N-nitrosodiethylamine, N-nitrosodimethylamine, N-nitrosodiphenylamine, N-nitrosomorpholine, and N-nitrosopiperidine were detected at concentrations above their LODs in 68 positive samples out of 594 authentic samples from seven sartans.