Papers - OHTAKE Kazuo
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L-NAME誘発性高血圧ラットの内皮機能不全と心臓リモデリングに対する魚油摂取の効果 Reviewed
薗田邦博, 河野有華, 大竹一男, 竹之内康広, 柴祥子, 小林順, 加園恵三
金城学院大学消費生活科学研究所紀要 28 ( 1 ) 13 - 28 2024.03
Language：Japanese Publishing type：Research paper (bulletin of university, research institution)
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異なるジューサーを用いて作製した野菜果物ジュースの硝酸塩含有量と官能検査の比較 Reviewed
薗田 邦博、河野 有華、清水 彩子、大竹 一男、柴 祥子、加園 恵三、小林 順
金城学院大学消費生活科学研究所紀要 27 ( 1 ) 11 - 20 2023.03
Language：Japanese Publishing type：Research paper (bulletin of university, research institution)
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非アルコール性脂肪肝炎モデル動物の肝炎と肝線維化に対するSodium nitriteとCaptoprilの併用投与による影響 Reviewed
河野 有華、 薗田 邦博、大竹 一男、 柴 祥子、北森 一哉、小林 順
金城学院大学消費生活科学研究所紀要 27 ( 1 ) 1 - 10 2023.03
Language：Japanese
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Nitric oxide bioavailability for red blood cell deformability in the microcirculation: A review of recent progress. Reviewed International journal
Jun Kobayashi, Kazuo Ohtake, Isamu Murata, Kunihiro Sonoda
Nitric oxide : biology and chemistry 129 25 - 29 2022.12
Authorship：Second author Language：English Publishing type：Research paper (scientific journal)
The rheological properties of red blood cells (RBCs) play an important role in their microcirculation. RBCs can elastically deform in response to mechanical forces to pass through narrow vessels for effective gas exchange in peripheral tissues. Decreased RBC deformability is observed in lifestyle-related diseases such as diabetes mellitus, hypercholesterolemia, and hypertension, which are pathological conditions linked to increased oxidative stress and decreased nitric oxide (NO) bioavailability. Redox-sensitive cysteine residues on RBC cytoskeletal proteins, such as α- and β-spectrins, responsible for membrane flexibility, are affected by prolonged oxidative stress, leading to reversible and irreversible oxidative modifications and decreased RBC deformability. However, endogenously, and exogenously generated NO protects RBC membrane flexibility from further oxidative modification by shielding redox-sensitive cysteine residues with a glutathione cap. Recent studies have shown that nitrate-rich diets and moderate exercise can enhance NO production to increase RBC deformability by increasing the interplay between RBCs and vascular endothelium-mediated NO bioavailability for microcirculation. This review focuses on the molecular mechanism of RBC- and non-RBC-mediated NO generation, and how diet- and exercise-derived NO exert prophylactic effects against decreased RBC deformability in lifestyle-related diseases with vascular endothelial dysfunction.
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Effects of dietary palmitoleic acid on vascular function in aorta of diabetic mice. Reviewed International journal
Yasuhiro Takenouchi, Yoshie Seki, Sachiko Shiba, Kazuo Ohtake, Koji Nobe, Keizo Kasono
BMC endocrine disorders 22 ( 1 ) 103 - 103 2022.04
Language：English Publishing type：Research paper (scientific journal)
BACKGROUND: Chronic hyperglycemia in diabetes causes atherosclerosis and progresses to diabetic macroangiopathy, and can lead to coronary heart disease, myocardial infarction and cerebrovascular disease. Palmitoleic acid (POA) is a product of endogenous lipogenesis and is present in fish and vegetable oil. In human and animal studies, POA is reported as a beneficial fatty acid related to insulin sensitivity and glucose tolerance. However, few studies have reported its effects on aortic function in diabetes. Here, we investigated the effects of POA administration on vascular function in KKAy mice, a model of type 2 diabetes. METHODS: Male C57BL/6 J (control) and KKAy (experimental) mice at the age of 14 weeks were used in the present study. For each mouse strain, one group was fed with reference diet and a second group was fed POA-containing diet for 2 weeks. The vascular reactivities of prepared aortic rings were then measured in an organ bath to determine if POA administration changed vascular function in these mice. RESULTS: KKAy mice treated with POA exhibited decreased plasma glucose levels compared with mice treated with reference diet. However, endothelium-dependent vasorelaxant responses to acetylcholine and protease-activated receptor 2 activating protein, which are attenuated in the aorta of KKAy mice compared to C57BL/6 J mice under a reference diet, were not affected by a 2-week POA treatment. In addition, assessment of vasoconstriction revealed that the phenylephrine-induced vasoconstrictive response was enhanced in KKAy mice compared to C57BL/6 J mice under a reference diet, but no effect was observed in KKAy mice fed a POA-containing diet. In contrast, there was an increase in vasoconstriction in C57BL/6 J mice fed the POA-containing diet compared to mice fed a reference diet. Furthermore, the vasoconstriction in aorta in both C57BL/6 J and KKAy mice fed a POA-containing diet were further enhanced under hyperglycemic conditions compared to normal glucose conditions in vitro. In the hyperinsulinemic, and hyperinsulinemic combined with hyperglycemic conditions, vasoconstriction was increased in KKAy mice fed with POA. CONCLUSION: These results suggest that POA intake enhances vasoconstriction under hyperglycemic and hyperinsulinemic conditions, which are characteristics of type 2 diabetes, and may contribute to increased vascular complications in diabetes.
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Beneficial Effects of Dietary Nitrite on a Model of Nonalcoholic Steatohepatitis Induced by High-Fat/High-Cholesterol Diets in SHRSP5/Dmcr Rats: A Preliminary Study. Reviewed International journal
Kunihiro Sonoda, Yuka Kono, Kazuya Kitamori, Kazuo Ohtake, Sachiko Shiba, Keizo Kasono, Jun Kobayashi
International journal of molecular sciences 23 ( 6 ) 2022.03
Language：English Publishing type：Research paper (scientific journal)
Nonalcoholic steatohepatitis (NASH) is a chronic liver disease that leads to liver cirrhosis and hepatocellular carcinoma. Endothelial dysfunction caused by hepatic lipotoxicity is an underlying NASH pathology observed in the liver and the cardiovascular system. Here, we evaluated the effect of dietary nitrite on a rat NASH model. Stroke-prone, spontaneously hypertensive 5/Dmcr rats were fed a high-fat/high-cholesterol diet to develop the NASH model, with nitrite or captopril (100 mg/L, each) supplementation in drinking water for 8 weeks. The effects of nitrite and captopril were evaluated using immunohistochemical analyses of the liver and heart tissues. Dietary nitrite suppressed liver fibrosis in the rats by reducing oxidative stress, as measured using the protein levels of nicotinamide adenine dinucleotide phosphate oxidase components and inflammatory cell accumulation in the liver. Nitrite lowered the blood pressure in hypertensive NASH rats and suppressed left ventricular chamber enlargement. Similar therapeutic effects were observed in a captopril-treated rat NASH model, suggesting the possibility of a common signaling pathway through which nitrite and captopril improve NASH pathology. In conclusion, dietary nitrite attenuates the development of NASH with cardiovascular involvement in rats and provides an alternative NASH therapeutic strategy.
DOI： 10.3390/ijms23062931
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Contribution of Pyk2 pathway and reactive oxygen species (ROS) to the anti-cancer effects of eicosapentaenoic acid (EPA) in PC3 prostate cancer cells. Reviewed International journal
Keiichi Oono, Kazuo Ohtake, Chie Watanabe, Sachiko Shiba, Takashi Sekiya, Keizo Kasono
Lipids in health and disease 19 ( 1 ) 15 - 15 2020.01
Authorship：Second author Language：English Publishing type：Research paper (scientific journal)
BACKGROUND: n-3 polyunsaturated fatty acids (n-3 PUFAs), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are thought to exert protective effects in cardiovascular diseases. In addition, n-3 PUFAs have demonstrated anti-cancer effects in vitro and in vivo. OBJECTIVE: We investigated the anti-cancer effects and mechanism of action of EPA on PC3 prostate cancer cells in vitro. METHODS: PC3 cells were treated with various concentrations of EPA, and cell survival and the abilities of migration and invasion were evaluated. The time course of the growth inhibitory effect of EPA on PC3 cells was also assessed. The mechanism underlying the anti-cancer effects of EPA was investigated by human phosphokinase and human apoptosis antibody arrays, and confirmed by western blot analysis. We also examined the contribution of reactive oxygen species (ROS) to the effects of EPA using the ROS inhibitor N-acetyl cysteine. RESULTS: EPA decreased the survival of PC3 cells in a dose-dependent manner within 3 h of application, with an effective concentration of 500 μmol/L. EPA inhibited proline-rich tyrosine kinase (Pyk)2 and extracellular signal-regulated kinase 1/2 phosphorylation as determined by western blotting and the antibody arrays. The growth of PC3 cells was inhibited by EPA, which was dependent on ROS induction, while EPA inhibited Pyk2 phosphorylation independent of ROS production. CONCLUSIONS: Inhibition of Pyk2 phosphorylation and ROS production contribute to the anticancer effects of EPA on PC3 cells.
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食事性亜硝酸塩摂取の炎症および免疫機能への影響と心血管系の健康とのかかわり Invited Reviewed
大竹一男 薗田邦博 小林 順
栄養学レビュー 28 ( 3 ) 175 - 193 2020
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
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Chronic Treatment with α-Lipoic Acid Improves Endothelium-Dependent Vasorelaxation of Aortas in High-Fat Diet-Fed Mice. Reviewed
Yasuhiro Takenouchi, Kazuhito Tsuboi, Kenji Ohsuka, Koji Nobe, Kazuo Ohtake, Yasuo Okamoto, Keizo Kasono
Biological & pharmaceutical bulletin 42 ( 9 ) 1456 - 1463 2019
Language：English Publishing type：Research paper (scientific journal)
α-Lipoic acid (ALA) is used as a dietary supplement and known as an anti-oxidant. The present study aimed to examine whether ALA improves endothelial dysfunction in high-fat diet-fed obese mice. After feeding a high-fat diet to Institute of Cancer Research (ICR) mice for 4 weeks, the mice were maintained with a high-fat diet (group HF) or a high-fat diet containing ALA (25 mg/d, group HF + ALA) for an additional 20 weeks. Age-matched normal diet-fed mice were also used (group Normal). Chronic oral treatment with ALA did not affect various plasma parameters or body weights. As compared with the aortas of Normal mice, those from HF mice showed impaired endothelium-dependent relaxation in response to clonidine. However, such an impairment was not observed in the aortas from HF + ALA mice. The plasma levels of thiobarbituric acid reactive substances, an indicator of oxidative stress, were significantly decreased in HF + ALA mice compared with HF mice, confirming the anti-oxidative effects of ALA. In addition, when the impaired clonidine-induced vasorelaxation of aortas from normal mice under high glucose conditions was used as a model of acute oxidative stress, the vasorelaxation responses were improved in the presence of ALA at 100 µM. Our results suggested that the chronic oral administration of ALA improves endothelial dysfunction in high-fat diet-fed obese mice possibly through the reduction in oxidative stress in vivo.
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Eicosapentaenoic acid ethyl ester improves endothelial dysfunction in type 2 diabetic mice. Reviewed International journal
Yasuhiro Takenouchi, Kazuo Ohtake, Koji Nobe, Keizo Kasono
Lipids in health and disease 17 ( 1 ) 118 - 118 2018.05
Language：English Publishing type：Research paper (scientific journal)
BACKGROUND: Eicosapentaenoic acid (EPA) is thought to have many beneficial effects, such as anti-atherosclerogenic and anti-inflammatory properties. However, few studies have reported its effects of endothelial dysfunction in diabetes and its direct effects on the aorta. Here, we investigated the effects of EPA treatment on impaired endothelium-dependent relaxation of the aorta in KKAy mice, a model of type 2 diabetes. METHODS: Male KKAy mice were fed a high-fat (HF) diet for 8 weeks to induce diabetes, after which they were divided into two groups. One group was fed a HF diet, and the other group was fed a HF diet containing EPA ethyl ester (EPA-E, 10 mg/day) for 4 weeks. Then, the vascular reactivities of prepared aortic rings were measured in an organ bath to determine if EPA-E administration changed vascular function in these diabetic mice. In addition, we examined effect of EPA-E and its metabolites to vascular action using aorta separated from C57BL/6 J mice. RESULTS: Although EPA-E administration did not change the plasma glucose and insulin levels in diabetic mice, total cholesterol levels were significantly decreased. The aorta extracted from EPA-E untreated diabetic mice showed impaired endothelium-dependent relaxation in response to acetylcholine (ACh). However, EPA-E administration improved the relaxation response to ACh to the control levels observed in non-diabetic C57BL/6 J mice. On the other hand, endothelium-independent relaxation in response to sodium nitroprusside did not significantly differ among these three groups. The enhanced contractile response by phenylephrine in diabetic mice was not altered by the administration of EPA-E. In addition, the direct administration of EPA-E metabolites such as EPA, docosahexaenoic acid, and docosapentaenoic acid led to vasodilation in the aortic rings of C57BL/6 J mice. CONCLUSION: These results showed that chronic EPA-E administration prevented the development of endothelial dysfunction in KKAy mice, partly via the direct action of EPA-E metabolites on the aorta.
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L-NAME誘発性高血圧ラットの血圧に対する亜硝酸塩とニフェジピンの相互作用 Reviewed
金城学院大学消費生活科学研究所紀要 22 ( 1 ) 7 - 16 2018.03
Language：Japanese
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Dietary Nitrite Attenuates Elastase-Induced Pulmonary Emphysema in a Mouse Model. Reviewed
Kunihiro Sonoda, Kazuo Ohtake, Maya Tagiri, Miku Hirata, Hazuki Tamada, Hiroyuki Uchida, Junta Ito, Jun Kobayashi
Biological & pharmaceutical bulletin 41 ( 12 ) 1818 - 1823 2018
Authorship：Second author Language：English Publishing type：Research paper (scientific journal)
Pulmonary emphysema (PE) is a major pathological feature of chronic obstructive pulmonary disease (COPD) and is characterized by proteolytic destruction of the alveolar structure and subsequent inflammation of the respiratory tract. We hypothesized that nitrite attenuates the development of PE via anti-inflammatory actions. PE was induced by intratracheal instillation of porcine pancreas elastase (PPE) in mice. Dietary nitrite dose-dependently (50 and 150 mg/L in drinking water) attenuated emphysematous development and macrophage accumulation in the alveolar parenchyma 21 d after PPE treatment. The present study shows that dietary nitrite might be a possible nutritional strategy in preventing the development of PE in mice.
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Dietary nitrite supplementation attenuates cardiac remodeling in L-NAME-induced hypertensive rats Reviewed International journal
Kunihiro Sonoda, Kazuo Ohtake, Hiroyuki Uchida, Junta Ito, Masaki Uchida, Hideshi Natsume, Hazuki Tamada, Jun Kobayashi
NITRIC OXIDE-BIOLOGY AND CHEMISTRY 67 1 - 9 2017.07
Authorship：Second author Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE
Loss of nitric oxide (NO) bioavailability underlies the development of hypertensive heart disease. We investigated the effects of dietary nitrite on N-G-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Sprague-Dawley rats were divided into five groups: an untreated control group, an L-NAME-treated group, and three other L-NAME-treated groups supplemented with 10 mg/L or 100 mg/L of nitrite or 100 mg/L of captopril in drinking water. After the 8-week experimental period, mean arterial blood pressure was measured, followed by sampling of blood and heart tissue for assessment of nitrite/nitrate levels in the plasma and heart, the plasma level of angiotensin II (AT II), and the heart transcriptional levels of AT II type 1 receptor (AT(1)R), transforming growth factor-beta (TGF-beta 1), and connective tissue proteins such as type 1 collagen and fibronectin. Heart tissue was analyzed by histopathological morphomety, including assessments of ventricular and coronary vascular hypertrophy and fibrosis, as well as immunohistochemistry analyses of myocardial expression of AT(1)R. L-NAME treatment reduced the plasma nitrate level and led to the development of hypertension, with increased plasma levels of AT II and increased heart transcriptional levels of AT(1)R and TGF-beta 1-mediated connective tissue proteins, showing myocardial and coronary arteriolar hypertrophy and fibrosis. However, dietary nitrite supplementation inhibited TGF-beta 1-mediated cardiac remodeling by suppressing AT II and AT(1)R. These results suggest that dietary nitrite levels achievable via a daily high-vegetable diet could improve hypertensive heart disease by inhibiting AT II-AT(1)R-mediated cardiac remodeling. (C) 2017 Elsevier Inc. All rights reserved.
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Dietary nitrite reverses features of postmenopausal metabolic syndrome induced by high-fat diet and ovariectomy in mice. Reviewed International journal
Kazuo Ohtake, Nobuyuki Ehara, Hiroshige Chiba, Genya Nakano, Kunihiro Sonoda, Junta Ito, Hiroyuki Uchida, Jun Kobayashi
American journal of physiology. Endocrinology and metabolism 312 ( 4 ) E300-E308 2017.04
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
Menopausal women are at greater risk of developing metabolic syndrome with reduced endothelial nitric oxide synthase (eNOS) activity. Hormone replacement therapy increases eNOS activity and normalizes some characteristics of metabolic syndrome. We hypothesized that nitric oxide (NO) supplementation should have a therapeutic effect on this syndrome. We examined the effect of dietary nitrite in a mouse model with postmenopausal metabolic syndrome induced by ovariectomy (OVX) and a high fat diet (HF). C57BL/6 female mice were divided into five groups, sham+normal fat diet (NF), sham+ HF, OVX+HF with or without sodium nitrite (50 mg and 150 mg/l) in the drinking water. Daily food intake and weekly body weight were monitored for 18 wk. OVX and HF significantly reduced plasma levels of nitrate/nitrite (NOx), and mice developed obesity with visceral hypertrophic adipocytes and increased transcriptional levels of monocyte chemoattractant protein-1, TNF-α, and IL-6 in visceral fat tissues. The proinflammatory state in the adipocytes provoked severe hepatosteatosis and insulin resistance in OVX+HF group compared with sham+NF group. However, dietary nitrite significantly suppressed adipocyte hypertrophy and transcriptions of proinflammatory cytokines in visceral fat in a dose-dependent manner. The improvement of visceral inflammatory state consequently reversed the hepatosteatosis and insulin resistance observed in OVX+HF mice. These results suggest that an endogenous NO defect might underlie postmenopausal metabolic syndrome and that dietary nitrite provides an alternative source of NO, subsequently compensating for metabolic impairments of this syndrome.
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NO-Rich Diet for Lifestyle-Related Diseases. Reviewed International journal
Jun Kobayashi, Kazuo Ohtake, Hiroyuki Uchida
Nutrients 7 ( 6 ) 4911 - 37 2015.06
Authorship：Second author Language：English Publishing type：Research paper (scientific journal)
Decreased nitric oxide (NO) availability due to obesity and endothelial dysfunction might be causally related to the development of lifestyle-related diseases such as insulin resistance, ischemic heart disease, and hypertension. In such situations, instead of impaired NO synthase (NOS)-dependent NO generation, the entero-salivary nitrate-nitrite-NO pathway might serve as a backup system for NO generation by transmitting NO activities in the various molecular forms including NO and protein S-nitrosothiols. Recently accumulated evidence has demonstrated that dietary intake of fruits and vegetables rich in nitrate/nitrite is an inexpensive and easily-practicable way to prevent insulin resistance and vascular endothelial dysfunction by increasing the NO availability; a NO-rich diet may also prevent other lifestyle-related diseases, including osteoporosis, chronic obstructive pulmonary disease (COPD), and cancer. This review provides an overview of our current knowledge of NO generation through the entero-salivary pathway and discusses its safety and preventive effects on lifestyle-related diseases.
DOI： 10.3390/nu7064911
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Dietary nitrite supplementation improves insulin resistance in type 2 diabetic KKA(y) mice. Reviewed International journal
Ohtake K, Nakano G, Ehara N, Sonoda K, Ito J, Uchida H, Kobayashi J
Nitric oxide : biology and chemistry 44 31 - 38 2015.01
Language：English Publishing type：Research paper (scientific journal)
BACKGROUND: Because insulin signaling is essential for endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) production, the loss of bioavailable NO might be a common molecular mechanism underlying the development of insulin resistance and endothelial dysfunction. Although dietary nitrite acts as a substrate for systemic NO generation, thereby serving as a physiological alternative source of NO for signaling, it is not precisely known how dietary nitrite affects type 2 diabetes mellitus. Here we report the therapeutic effects of dietary nitrite on the metabolic and histological features of KKA(y) diabetic mice. METHODS: KKA(y) mice were divided into three groups (without nitrite, and with 50 mg/L and 150 mg/L nitrite in drinking water), and two groups of C57BL/6J mice served as controls (without nitrite and with 150 mg/L nitrite in drinking water). After 10 weeks, blood samples, visceral adipose tissues, and gastrocnemius muscles were collected after a 16-hour fast to assess the homeostasis model assessment of insulin resistance (HOMA-IR) levels, the histology of the adipose tissue, insulin-stimulated sequential signaling to glucose transporter 4 (GLUT4), and nitrite and nitrate contents in the muscle using an HPLC system. RESULTS: KKA(y) mice developed obesity with enhanced fasting plasma levels of glucose and insulin and exhibited increased HOMA-IR scores compared with the C57BL/6J control mice. Dietary nitrite dose-dependently reduced the size of the hypertrophic adipocytes and TNF-α transcription in the adipose tissue of KKA(y) diabetic mice, which also restored the insulin-mediated signal transduction, including p85 and Akt phosphorylation, and subsequently restored the GLUT4 expression in the skeletal muscles. CONCLUSIONS: These results suggest that dietary nitrite provides an alternative source of NO, and subsequently improves the insulin-mediated signaling and the metabolic and histological features in KKA(y) diabetic mice.
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A Mechanism Enhancing Macromolecule Transport Through Paracellular Spaces Induced by Poly-L-Arginine: Poly-L-Arginine Induces the Internalization of Tight Junction Proteins via Clathrin-Mediated Endocytosis Reviewed International journal
Tsutomu Yamaki, Yusuke Kamiya, Kazuo Ohtake, Masaki Uchida, Toshinobu Seki, Hideo Ueda, Jun Kobayashi, Yasunori Morimoto, Hideshi Natsume
PHARMACEUTICAL RESEARCH 31 ( 9 ) 2287 - 2296 2014.09
Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER/PLENUM PUBLISHERS
Poly-L-arginine (PLA) enhances the paracellular permeability of the Caco-2 cell monolayer to hydrophilic macromolecules by disappearance of tight junction (TJ) proteins from cell-cell junctions. However, the mechanism of the disappearance of TJ proteins in response to PLA has been unclear. In this study, we investigated the mechanism of disappearance of TJ proteins from cell-cell junctions after the application of PLA to Caco-2 cell monolayers.
The membrane conductance (G(t)), FITC-dextran (FD-4) permeability, and localization of TJ proteins were examined after the treatment of Caco-2 cell monolayers with PLA in the presence of various endocytosis inhibitors. In addition, the localization of endosome marker proteins was also observed.
Clathrin-mediated endocytosis inhibitors suppressed the increase in G(t) and P-app of FD-4 induced by PLA, and also significantly suppressed the disappearance of TJ proteins induced by PLA. Furthermore, occludin, one of the TJ proteins, colocalized with early endosome and recycling endosomes after the internalization of occludin induced by PLA, and then was recycled to the cell-cell junctions.
PLA induced the transient internalization of TJ proteins in cell-cell junctions via clathrin-mediated endocytosis, subsequently increasing the permeability of the Caco-2 cell monolayer to FD-4 via a paracellular route. -
Aldehyde dehydrogenase 2 partly mediates hypotensive effect of nitrite on L-NAME-induced hypertension in normoxic rat. Reviewed International journal
Kunihiro Sonoda, Kazuo Ohtake, Yoshinori Kubo, Hiroyuki Uchida, Masaki Uchida, Hideshi Natsume, Miya Kobayashi, Jun Kobayashi
Clinical and experimental hypertension (New York, N.Y. : 1993) 36 ( 6 ) 410 - 8 2014
Authorship：Second author Language：English Publishing type：Research paper (scientific journal)
Nitrite has become a topic of interest in the field of medical research because of its potential therapeutic role as an alternative source of nitric oxide (NO). While the bioconversion of nitrite to NO occurs via either nonenzymatic or enzymatic reduction under acidic or hypoxic conditions, little is known about its conversion to NO under normoxic conditions. Because of a recent report of aldehyde dehydrogenase 2 (ALDH2)-catalyzed glyceryl trinitrate (GTN) vasorelaxation by denitration of GTN to 1,2-glyceryl dinitrate (1,2-GDN) and nitrite, we therefore investigated a catalytic activity of ALDH2 for nitrite reduction and subsequent effect on N(ω)-nitro-l-arginine methyl ester (l-NAME)-induced hypertension in normoxic rat. Male Sprague-Dawley rats treated with l-NAME in drinking water for 3 weeks developed hypertension with significantly reduced plasma levels of nitrite and nitrate. The intravenous injection of sodium nitrite lowered the arterial pressure in a dose-dependent manner (17, 50 and 150 μmol/kg). Pretreatment with ALDH2 inhibitors (cyanamide and chloral hydrate) partially inhibited the hypotensive responses to sodium nitrite. In addition, cyanamide significantly delayed the nitrite clearance from plasma and most of the organs examined during the experimental period. These results suggest that ALDH2 may be at least in part involved in nitrite-mediated hypotensive effects and nitrite catalysis in many organs of normoxic rats.
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Tsutomu Yamaki, Kazuo Ohtake, Keiko Ichikawa, Masaki Uchida, Hiroyuki Uchida, Shinji Oshima, Kazuhiko Juni, Jun Kobayashi, Yasunori Morimoto, Hideshi Natsume
Biological and Pharmaceutical Bulletin 36 ( 3 ) 432 - 441 2013.03
Authorship：Second author Language：English Publishing type：Research paper (scientific journal)
We investigated whether poly-l-arginine (PLA) enhances the paracellular permeability of the Caco-2 monolayer to hydrophilic macromolecules and clarified the disposition of tight junction (TJ) proteins. The transepithelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC)-dextran (FD-4) permeation were determined after treatment with PLA. TJ proteins were visualized using immunofluorescence microscopy after PLA exposure and depletion, and their expression levels were determined. The barrier function of TJs was also evaluated by measuring the alterations in the TEER and in the localization of TJ proteins. PLA induced an increase in hydrophilic macromolecule, FD-4, permeation through Caco-2 cell monolayers and a decrease in the TEER in a concentration-dependent manner, without any significant impact on the cell viability. This increased paracellular permeability induced by PLA was found to be internalized of claudin-4, ZO-1, tricellulin and mainly occludin from cell-cell junction to the subcellular space. ZO-1 appeared to play an important role in the reconstitution of TJ strand structures following PLA depletion. These results indicate that the PLA led to the internalization of TJ proteins to the subcellular space, subsequently increasing the permeability of the Caco-2 cell monolayer to FD-4 via a paracellular route. © 2013 The Pharmaceutical Society of Japan.
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Effect of poly-L-arginine on intestinal absorption of hydrophilic macromolecules in rats. Reviewed
Tsutomu Yamaki, Masaki Uchida, Yusuke Kuwahara, Yohei Shimazaki, Kazuo Ohtake, Mitsutoshi Kimura, Hiroyuki Uchida, Jun Kobayashi, Masahiko Ogihara, Yasunori Morimoto, Hideshi Natsume
Biological & pharmaceutical bulletin 36 ( 3 ) 496 - 500 2013
Language：English Publishing type：Research paper (scientific journal)
We have already reported that poly-L-arginine (PLA) remarkably enhanced the in vivo nasal absorption of hydrophilic macromolecules without producing any significant epithelial damage in rats. In the present study, we examined whether PLA could enhance the absorption of a model hydrophilic macromolecule, fluorescein isothiocyanate-dextran (FD-4), across the intestinal mucosa, as well as the nasal mucosa, by an in situ closed-loop method using the rat intestine. PLA was found to enhance the intestinal absorption of FD-4 in a concentration-dependent manner within the concentrations investigated in this study, but segment-specific differences were found to be associated with this effect (ileum>jejunum>duodenum≧colon). The factors responsible for the segment-specific differences were also investigated by intestinal absorption studies using aprotinin, a trypsin inhibitor, and an analysis of the expression of occludin, a tight junction protein. In the small intestine, the differences in the effect of PLA on the absorption of FD-4 may be related to the enzymatic degradation of PLA. In the colon, the reduced effect of PLA on the absorption of FD-4 may be related to the smaller surface area for absorption and the higher expression of occludin compared with other segments.