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Singh P, Sharma B, Gupta S, Sharma BM. In vivo and in vitro attenuation of naloxone-precipitated experimental opioid withdrawal syndrome by insulin and selective KATP channel modulator. Psychopharmacology (Berl) 2015; 232:465-75. [PMID: 25059539 DOI: 10.1007/s00213-014-3680-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 07/02/2014] [Indexed: 12/01/2022]
Abstract
RATIONALE Opiate exposure for longer duration develops state of dependence in humans and animals, which is revealed by signs and symptoms of withdrawal precipitated by opioid receptor antagonists. The sudden withdrawal of opioids produces a withdrawal syndrome in opioid-dependent subjects. Insulin and ATP-sensitive potassium (KATP) channel-mediated glucose homeostasis have been shown to modulate morphine withdrawal. OBJECTIVE Present study has been structured to investigate the role of insulin and pharmacological modulator of KATP channel (gliclazide) in experimental morphine withdrawal syndrome, both invivo and invitro. METHODS In this study, naloxone-precipitated morphine withdrawal syndrome in mice (invivo) as well as in rat ileum (invitro) were utilized to assess opioid withdrawal phenomenon. Morphine withdrawal syndromes like jumping and rearing frequency, forepaw licking, circling, fore paw tremor, wet dog shake, sneezing, overall morphine withdrawal severity (OMWS), serum glucose, brain malondialdehyde (MDA), glutathione (GSH), nitrite/nitrate, and calcium (Ca(+2)) were assessed. RESULTS Naloxone has significantly increased morphine withdrawal syndrome, both invivo and invitro. Insulin and gliclazide have significantly attenuated, naloxone induced behavioral changes like jumping and rearing frequency, forepaw licking, wet dog shake, sneezing, straightening, circling, OMWS, and various biochemical impairments such as serum glucose, brain MDA, GSH, nitrite/nitrate, and Ca(+2) in morphine-dependent animals (invivo). In vitro, insulin and gliclazide have significantly reduced naloxone-induced contraction in morphine-withdrawn rat ileum preparation. CONCLUSIONS Insulin and gliclazide (KATP channel blocker) have attenuated naloxone-precipitated morphine withdrawal syndrome, both invivo and invitro. Thus, insulin and KATP channel modulation may provide new avenues for research in morphine withdrawal.
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Affiliation(s)
- Prabhat Singh
- Neuropharmacology Laboratory, Department of Pharmacology, School of Pharmacy, Bharat Institute of Technology, Partapur Bypass, Meerut, 250103, Uttar Pradesh, India
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Ng CF, Koon CM, Cheung DWS, Lam MY, Leung PC, Lau CBS, Fung KP. The anti-hypertensive effect of Danshen (Salvia miltiorrhiza) and Gegen (Pueraria lobata) formula in rats and its underlying mechanisms of vasorelaxation. JOURNAL OF ETHNOPHARMACOLOGY 2011; 137:1366-1372. [PMID: 21855622 DOI: 10.1016/j.jep.2011.08.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 08/01/2011] [Accepted: 08/02/2011] [Indexed: 05/31/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Radix Salviae miltiorrhizae (Danshen) and Radix Puerariae lobatae (Gegen) have long been used in traditional Chinese Medicine and serve as the principal herbs in treating cardiovascular disease. AIMS OF THE STUDY In the present study, an aqueous extract comprising Danshen and Gegen in the ratio of 7:3 (DG) was investigated for its anti-hypertension in vivo and vasodilative activities ex vivo. MATERIALS AND METHODS The anti-hypertensive effect of DG extract was investigated in spontaneously hypertensive rat (SHR) by measuring systolic blood pressure (SBP). Oral administration of DG extract was started at age of 6 weeks and 14 weeks for the preventive and therapeutic studies, respectively. Blood pressure was measured by tail-cuff method biweekly for 12 weeks. The ex vivo vasodilative activities of DG extract, its dependency on endothelium and the involvement of nitric oxide, prostacyclin and potassium channels were investigated using isolated rat aorta ring in organ bath. RESULTS For in vivo study, systolic blood pressure was significantly reduced in DG extract-treated groups (90.2 and 300 mg/kg) as compared with the SHR control in both preventive and therapeutic studies. However, DG extract was unable to suppress or delay the onset of hypertension in the preventive study. For ex vivo study, the results showed that DG extract induced a concentration-dependent relaxation in aorta and persisted response was observed with the removal of endothelium. Besides, pretreatment with a non-selective potassium channel inhibitor tetraethylammonium (TEA) also significantly inhibited DG extract-induced vasodilation. Further investigations on specific potassium channel blockers revealed that ATP-sensitive potassium (K(ATP)) channel inhibitor glibenclamide, inward rectifier potassium (Kir) inhibitor barium chloride and voltage-dependent potassium (K(v)) channel inhibitor 4-aminopyridine, but not BK(Ca) channel inhibitor iberiotoxin, exerted significant inhibition on DG extract-induced vasodilation. CONCLUSIONS The results of in vivo SHR animal model suggested that DG aqueous extract possessed blood pressure lowering effect on both pre- and post-hypertensive rats, which could be explained by its endothelium-independent vasodilation via the opening of K(ATP), Kir and K(v) channels.
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MESH Headings
- Administration, Oral
- Animals
- Antihypertensive Agents/administration & dosage
- Antihypertensive Agents/isolation & purification
- Antihypertensive Agents/pharmacology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/physiopathology
- Blood Pressure/drug effects
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drugs, Chinese Herbal/administration & dosage
- Drugs, Chinese Herbal/isolation & purification
- Drugs, Chinese Herbal/pharmacology
- Epoprostenol/metabolism
- Hypertension/drug therapy
- Hypertension/metabolism
- Hypertension/physiopathology
- Hypertension/prevention & control
- KATP Channels/drug effects
- KATP Channels/metabolism
- Male
- Nitric Oxide/metabolism
- Plants, Medicinal
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Inwardly Rectifying/drug effects
- Potassium Channels, Inwardly Rectifying/metabolism
- Potassium Channels, Voltage-Gated/drug effects
- Potassium Channels, Voltage-Gated/metabolism
- Pueraria/chemistry
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Rats, Sprague-Dawley
- Salvia miltiorrhiza/chemistry
- Time Factors
- Vasodilation/drug effects
- Vasodilator Agents/administration & dosage
- Vasodilator Agents/isolation & purification
- Vasodilator Agents/pharmacology
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Affiliation(s)
- C F Ng
- Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Li Z, Xu ZL, Liang J, Wu JC, Hu CW, Xie H, Ma WC, Jiang HC, Yang BF, Dong DL. Tetraethylammonium enhances the rectal and colonic motility in rats and human in vitro. Naunyn Schmiedebergs Arch Pharmacol 2011; 384:147-55. [PMID: 21630039 DOI: 10.1007/s00210-011-0658-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 05/15/2011] [Indexed: 12/20/2022]
Abstract
Hirschsprung's disease is the congenital absence of generating the peristaltic contractions transmitting from the proximal colon to rectum. We previously have found that tetraethylammonium (TEA), the nonselective Ca(2+)-activated K(+) channel blocker, increases the maximal contractile force and the amplitude of the contraction in rat duodenum. The present study is to test the effect of TEA on motility of colon and rectum from rats and Hirschsprung's disease patients in vitro, in order to find an alternative method to improve the syndrome of Hirschsprung's disease. The rectal and colonic motility was recorded by a tension transducer connected to a biology function experiment system. Histology was analyzed with standard hematoxylin and eosin staining. TEA (1, 3, and 5 mM) significantly increased the amplitude and frequency of contractility of colon and rectum from rats in longitudinal and circular direction. TEA at 5 and 15 mM concentrations showed no effect on histology of colon and rectum from rats that were administered locally with TEA into colon lumen from anus for 10 days. TEA at 15 mM increased the amplitude and frequency of contractions of the colon and rectum from Hirschsprung's disease patients. Our data showed that TEA increased the contractility of colon and rectum from rats and Hirschsprung's disease patients in vitro, suggesting that local administration of TEA in colon or rectum lumen might be an alternative method to ameliorate the syndrome of Hirschsprung's disease patients who are not cured completely by surgery or not suitable for surgery.
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Affiliation(s)
- Zhe Li
- Department of Pharmacology (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, People's Republic of China
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Lee HW, Baak CH, Lee MY, Kim YC. Spontaneous contractions augmented by cholinergic and adrenergic systems in the human ureter. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:37-41. [PMID: 21461239 DOI: 10.4196/kjpp.2011.15.1.37] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 02/10/2011] [Accepted: 02/14/2011] [Indexed: 11/15/2022]
Abstract
Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3~4 times within 5 minutes in the longitudinal group. ACh (10(-4) M) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of 10(-5) M glibenclamide. Receptor tyrosine kinase (c-kit) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.
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Affiliation(s)
- Hyun Woo Lee
- Department of Life and Leisure Sport/Sport Industry, College of Sports Science, Chung-Ang University, Seoul 156-756, Korea
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Tanaka K, Yamamoto Y, Ogino K, Tsujimoto S, Saito M, Uozumi N, Shimizu T, Hisatome I. Cytosolic phospholipase A2alpha contributes to blood pressure increases and endothelial dysfunction under chronic NO inhibition. Arterioscler Thromb Vasc Biol 2011; 31:1133-8. [PMID: 21350197 DOI: 10.1161/atvbaha.110.218370] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Nitric oxide (NO) is an important modulator of cardiovascular function. In this study, we examined whether cytosolic phospholipase A2α (cPLA2α), an initial enzyme in the arachidonic acid pathway, is involved in blood pressure (BP) elevation in a murine model of chronic NO inhibition. METHODS AND RESULTS cPLA2α gene-deficient mice (cPLA2α-/-) and wild-type mice (WT) were administered the NO synthesis inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) for 4 weeks. Before treatment, BP was comparable in both groups; it increased significantly in the WT but not in the cPLA2α-/- after treatment. Bone marrow transplantation experiments showed that cPLA2α in blood cells and plasma eicosanoid concentrations were not involved in BP elevation by L-NAME treatment. Activation of cPLA2α and subsequent production of eicosanoids in the aortic endothelium but not in aortic smooth muscle cell, heart, or kidney was observed after L-NAME treatment. Aortic ring assays revealed that endothelial function was comparable in both groups of mice before treatment. L-NAME treatment disturbed endothelial function in WT but not in cPLA2α-/-. CONCLUSIONS These results suggest that endothelial cPLA2α may play a principal role in L-NAME-induced hypertension and may be a target molecule for maintaining endothelial function under NO inhibition.
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Affiliation(s)
- Kohei Tanaka
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science, and Center for Clinical Residency Program, Tottori University Hospital, 36-1 Nishi-machi, Yonago 683-8504, Japan
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Ting HJ, Murray WJ, Khasawneh FT. Repurposing an old drug for a new use: glybenclamide exerts antiplatelet activity by interacting with the thromboxane A(2) receptor. Acta Pharmacol Sin 2010; 31:150-9. [PMID: 20139897 DOI: 10.1038/aps.2009.195] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
AIM To investigate the potential antagonistic activity of the antidiabetic agent glybenclamide for the human platelet thromboxane A(2) receptor (abbreviated as TPR). METHODS Platelets were obtained from healthy donors. Aggregation studies were performed in a model 700 aggregometry system. Radioactivity was counted in a Beckman LS 6000 liquid scintillation counter and calcium imaging was performed using an LS50B PerkinElmer Fluorescence Spectrometer. RESULTS It was found that glybenclamide: 1) inhibited aggregation induced by the TPR agonist U46619 (IC(50)=2.3+/-0.31 micromol/L) and by the thromboxane A(2) precursor arachidonic acid (IC(50)=2.6+/-0.24 micromol/L); 2) displaced SQ29,548 from its binding sites on platelets; 3) lacked any detectable effects on aggregation stimulated by ADP, or the thrombin receptor activating-peptide 4; 4) blocked calcium mobilization induced by U46619, but not by ADP; and 5) failed to raise cAMP levels. CONCLUSION The findings indicate that glybenclamide exerts inhibitory effects on platelets by interacting with TPR. Thus, glybenclamide or a rationally designed derivative has the potential to serve as an antithrombotic agent.
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Jones RL, Giembycz MA, Woodward DF. Prostanoid receptor antagonists: development strategies and therapeutic applications. Br J Pharmacol 2009; 158:104-45. [PMID: 19624532 PMCID: PMC2795261 DOI: 10.1111/j.1476-5381.2009.00317.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Accepted: 04/07/2009] [Indexed: 01/17/2023] Open
Abstract
Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP(1), EP(2) ...) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP(1), TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP(2)). While some antagonists are structurally related to the natural agonist, most recent compounds are 'non-prostanoid' (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD(2) (acting on DP(1) and DP(2) receptors) and PGE(2) (on EP(1) and EP(4) receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage.
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Affiliation(s)
- R L Jones
- Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, UK.
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Gok S, Izanli-Paksoy A, Vural K. Contribution of RhoA kinase and protein kinase C to weak relaxant effect of pinacidil on carbachol-induced contractions in sensitized guinea-pig trachealis. Arch Pharm Res 2009; 32:243-50. [DOI: 10.1007/s12272-009-1229-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2008] [Revised: 01/19/2009] [Accepted: 01/19/2009] [Indexed: 11/30/2022]
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Wareing M, Greenwood SL, Fyfe GK, Baker PN, Taggart MJ. Glibenclamide Inhibits Agonist-induced Vasoconstriction of Placental Chorionic Plate Arteries. Placenta 2006; 27:660-8. [PMID: 16026833 DOI: 10.1016/j.placenta.2005.05.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 05/16/2005] [Accepted: 05/16/2005] [Indexed: 11/26/2022]
Abstract
BACKGROUND Preliminary data suggest that K(ATP) channels may be expressed in placental arteries and veins [Wareing M, Turner C, Greenwood SL, Baker PN, Fyfe GK. Expression of mRNA encoding K+ channels in chorionic plate arteries and veins. J Soc Gynecol Investig 2004;11:353A]. However, no data exist on glibenclamide's effects in placental chorionic plate arteries. AIM To assess the effect of glibenclamide on placental chorionic plate arterial vasoconstriction. METHODS Arteries were dissected from placental chorionic plate biopsies obtained at term from uncomplicated pregnancies (N=63). Arteries were mounted onto a wire myograph in HCO3- -buffered physiological salt solution (PSS) at 37 degrees C (5% O2/5% CO2 bubbling) and normalised at 0.9 of L5.1 kPa. Constriction viability was assessed with 120 mmol l(-1) potassium solution (KPSS). Dose-response curves were produced with the thromboxane-mimetics U46619 and U44069 (10(-10)-2 x 10(-6)M), arginine vasopressin (10(-10)-5 x 10(-8)M) and endothelin-1 (10(-11)-3 x 10(-7)M) in the presence or absence of 50 micromol l(-1) glibenclamide. The effect of glibenclamide on arginine vasopressin- and U46619-induced constriction was also assessed in the presence of the cyclo-oxygenase inhibitor indomethacin (10 micromol l(-1)). RESULTS Pre-incubation with 50 micromol l(-1) glibenclamide significantly right-shifted dose-response curves to all vasoconstrictive agonists tested (repeated measures ANOVA). Indomethacin did not modify the inhibitory effect of glibenclamide. CONCLUSION Glibenclamide's effects on agonist-induced constrictions are unlikely to be via an inhibition of ATP-sensitive K+ channels, and with U46619- and U44069-induced constrictions, glibenclamide may be acting as a competitive antagonist of thromboxane receptors.
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Affiliation(s)
- M Wareing
- Maternal and Fetal Health Research Centre, University of Manchester, St. Mary's Hospital, Hathersage Road, Manchester, M13 0JH, UK.
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Nobe K, Miyatake M, Sone T, Honda K. High-Glucose-Altered Endothelial Cell Function Involves Both Disruption of Cell-to-Cell Connection and Enhancement of Force Development. J Pharmacol Exp Ther 2006; 318:530-9. [PMID: 16699065 DOI: 10.1124/jpet.106.105015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vascular endothelial cells (ECs), which regulate vascular tonus, serve as a barrier at the interface of vascular tissue. It is generally believed that alteration of this barrier is correlated with diabetic complications; however, a detailed mechanism has not been elucidated. This study examined alteration of bovine arterial EC functions stimulated by a thromboxane A2 analog (9,11-dideoxy-11 alpha,9 alpha-epoxymethano prostaglandin F(2 alpha); U46619) under normal and high-glucose (HG) conditions. U46619 treatment increased EC layer permeability in a time- and dose-dependent fashion. This response initially disrupted calcium-dependent EC-to-EC connections, namely, vascular endothelial cadherin (VE-CaD). Thereafter, EC force development in association with morphological changes was detected employing a reconstituted EC fiber technique, resulting in paracellular hole formation in the EC layer. Thus, we confirmed that U46619-induced enhancement of EC layer permeability involves these sequential steps. Similar trials were performed using a concentration twice that of normal glucose (22.2 mM glucose for 48 h). This treatment significantly enhanced U46619-induced EC layer permeability; furthermore, increases in both rate of VE-CaD disruption and EC fiber contraction were evident. Inhibition of calcium-independent protein kinase C and diacylglycerol kinase indicated that the glucose-dependent increase in VE-CaD disruption was mediated by a calcium-independent mechanism. Moreover, EC contraction was regulated by a typical calcium-independent pathway associated with rho kinase and actin stress fiber. Contraction was also enhanced under HG conditions. This investigation revealed that glucose-dependent enhancement of EC layer permeability is related to increases in VE-CaD disruption and EC contraction. Increases in both parameters were mediated by alteration of a calcium-independent pathway.
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Affiliation(s)
- Koji Nobe
- Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-0555, Japan.
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Kamata K, Makino A, Kanie N, Oda SI, Matsumoto T, Kobayashi T, Kikuchi T, Nishimura M, Honda T. Effects of anthocyanidin derivative (HK-008) on relaxation in rat perfused mesenterial bed. J Smooth Muscle Res 2006; 42:75-88. [PMID: 17001114 DOI: 10.1540/jsmr.42.75] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Anthocyanins, which are responsible for a variety of bright colors (including red, blue, and purple) in fruits, vegetables, and flowers, are consumed as dietary polyphenols. Anthocyanin-containing fruits are thought to decrease coronary heart disease and are used in anti-diabetic preparations. Diabetes is associated with a variety of cardiovascular complications that may be mediated by endothelial dysfunction, and so this study was designed mainly to characterize the influence of a synthesized anthocyanidin derivative (HK-008) over acetylcholine (ACh)-induced relaxation in mesenteric arterial beds isolated from rats. In a glucose-tolerance test in intact rats, HK-008 (30 mg/kg) reduced the glucose level as effectively as the same dose of glibenclamide. The aortic relaxation induced by pinacidil (an ATP-sensitive potassium channel opener) was greatly inhibited by glibenclamide (10 microM), and also significantly inhibited by HK-008 (10 microM). Interestingly, the ACh-induced relaxation in the perfused, preconstricted mesenteric arterial bed was significantly enhanced by HK-008 (10 microM), and this enhancement was significantly attenuated by indomethacin (10 microM). The ACh-induced mesenteric relaxation was impaired by an increase in oxidative stress, viz. superoxide-generating treatment [xanthine oxidase (XO; 0.1 U/ml) plus hypoxanthine (HX; 10 microM)]. However, this impairment was strongly suppressed by HK-008 (10 microM). These results suggest that HK-008 increases endothelium-induced relaxation by suppressing oxidative stress or modulating prostanoids signaling. This compound may therefore be useful against certain cardiovascular disorders.
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Affiliation(s)
- Katsuo Kamata
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Ebara 2-4-41, Shinagawa-ku, Tokyo 142-8501, Japan.
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