Canadian Journal of Physiology and Pharmacology (Can J Physiol Pharmacol)

Publications in this journal

• Article: The long chain fatty acid oleate activates mouse intestinal afferent nerves in vitro.

  W Andrew Webster, Michael J Beyak
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  ABSTRACT: Vagal afferents innervating the gastrointestinal tract serve an important nutrient-sensing function, and these signals contribute to satiety. Detection of nutrients occurs largely through the release of mediators from specialized enteroendocrine cells within the mucosa of the gastrointestinal tract. The signaling pathways leading to vagal afferent activation are not clear; however, previous in-vivo studies have implicated a role for cholecystokinin (CCK). We used an in vitro intestinal afferent extracellular recording preparation to study the effect of luminal perfusion of the long chain fatty acid oleate on mouse intestinal afferent activity. Oleate activated intestinal afferents in a concentration-dependent fashion, with an EC50 value of approximately 25 mmol/L. The L-type calcium channel blocker nicardipine attenuated the effect of oleate. Vagotomy resulted in a significant (>60%) reduction of the responses to both oleate and CCK. The CCK-1 receptor antagonist lorglumide nearly abolished responses to CCK and oleate. Our experiments therefore suggest that oleate activates intestinal afferents, with vagal afferents primarily involved; however, nonvagal fibres also contribute. The activation is dependent on CCK release, likely via activation of L-type channels on mucosal enteroendocrine cells, finally resulting in activation of CCK-1 receptors on the afferent terminals.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):375-9.
• Article: Chronic intermittent hypobaric hypoxia prevents cardiac dysfunction through enhancing antioxidation in fructose-fed rats.

  Jing-Jing Zhou, Yan Wei, Li Zhang, Jiao Zhang, Lan-Ying Guo, Chao Gao, De-Pei Li, Yi Zhang
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  ABSTRACT: High-fructose intake induces metabolic syndrome and cardiac dysfunction. Chronic intermittent hypobaric hypoxia (CIHH) preserves cardiac function during ischemia. We hypothesized that CIHH restores the impaired cardiac function in fructose-fed rats. Sprague-Dawley rats were randomly subject to treatment with fructose (10% fructose in drinking water for 6 weeks), CIHH (simulated 5000 m altitude, 6 h/day for 6 weeks in a hypobaric chamber), and CIHH plus fructose groups. In addition to an increase in blood pressure, fructose feeding caused elevated serum levels of glucose, fasting insulin and insulin C peptide, triglyceride, cholesterol, and mass ratio of heart to body. CIHH treatment decreased the arterial blood pressure, serum levels of biochemical markers, and cardiac hypertrophy in fructose-fed rats. Furthermore, CIHH treatment improved the recovery of left ventricular function after ischemia-reperfusion procedure (30 min global no-flow ischemia followed by 60 min of reperfusion) in rats with or without fructose feeding. In addition, CIHH treatment caused a significant increase in superoxide dismutase (SOD) activity and decrease in malondialdehyde level in cardiac myocardium experiencing ischemia-reperfusion in control and fructose-fed rats. Collectively, these data suggest that CIHH improve impaired cardiac function in fructose-fed rats through enhancing antioxidation in the myocardium.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):332-7.
• Article: Investigating the autonomic nervous system and cognitive functions as potential mediators of an association between cardiovascular disease and driving performance.

  Jeffrey Gaudet, Mathieu F Bélanger, Hélène Corriveau, Said Mekary, Dean Hay, Michel J Johnson
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  ABSTRACT: Cardiovascular disease (CVD) impacts the autonomic nervous system and cognitive functions related to activities of daily living, including driving an automobile. Although CVD has been linked to unsafe driving, mechanisms underlying this relationship remain elusive. The aim of this study was to examine the role of cognitive functions and the autonomic nervous system as potential mediators of driving performance. Nineteen individuals having recently suffered a cardiac event and 16 individuals with no history of CVD completed a simulated drive using a STISIM simulator to assess driving performance. Heart rate was recorded throughout testing using a Polar RS800CX heart rate monitor, and measures of executive, orienting, and alerting functions were obtained through the Attention Network Test. We used the Baron and Kenny analysis method to assess potential mediating effects of the relationship between CVD and driving performance. Executive function was the only potential mediator investigated to be associated with driving (p < 0.01) and CVD (p < 0.05); however, it did not appear to play a mediating role (p = 0.28). These results suggest that individuals with CVD exhibit decrements in complex cognitive tasks such as driving and that further research is needed to better understand the mechanisms underlying this relationship.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):346-52.
• Article: Physiological focus on the erythropoietin-hepcidin-ferroportin axis.

  María Cecilia D'Anna, Marta Elena Roque
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  ABSTRACT: To analyze the interconnection between erythropoiesis and iron metabolism, one of the issues raised in this study was to know iron bioavailability under physiopathological conditions. Our aim was to understand the functional axis response composed of erythropoietin (Epo)-hepcidin-ferroportin (FPN), when 2 dysfunctional states coexist, using an animal model of iron overload followed by hypoxia. FPN and prohepcidin were assessed by immunohistochemistry using rabbit anti-mouse FPN polyclonal and prohepcidin monoclonal antibodies. Goat-labeled polymer - horseradish peroxidase anti-rabbit EnVision + System (DAB) was used as the secondary antibody. Epo levels were measured by ELISA. Tissue iron was studied by Prussian blue iron staining. Erythropoietic response was assessed using conventional hematological tests. Iron overload increased prohepcidin that remained high in hypoxia, coexisting with high levels of Epo in hypoxia, with or without iron overload. In hypoxia, FPN was clearly evident in reticuloendothelial macrophages, more than in hypoxia with iron overload. Interestingly, duodenal FPN was clearly identified on the basolateral membrane in hypoxia, with or without iron overload. Our data indicate that 2 signals could induce the cell-specific response as follows: (i) iron signal, induced prohepcidin, which reduced reticuloendothelial FPN and reduced iron availability; and (ii) hypoxia signal, stimulated Epo, which affected iron absorption by stabilizing duodenal FPN and allowed iron supply to erythropoiesis independently of store size.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):338-45.
• Article: The effect of portacaval anastomosis on the expression of glutamine synthetase and ornithine aminotransferase in perivenous hepatocytes.

  Robin da Silva, Oliver Levillain, John T Brosnan, Silvia Araneda, Margaret E Brosnan
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  ABSTRACT: There is functional zonation of metabolism across the liver acinus, with glutamine synthetase restricted to a narrow band of cells around the terminal hepatic venules. Portacaval anastomosis, where there is a major rerouting of portal blood flow from the portal vein directly to the vena cava bypassing the liver, has been reported to result in a marked decrease in the activity of glutamine synthetase. It is not known whether this represents a loss of perivenous hepatocytes or whether there is a specific loss of glutamine synthetase. To answer this question, we have determined the activity of glutamine synthetase and another enzyme from the perivenous compartment, ornithine aminotransferase, as well as the immunochemical localization of both glutamine synthetase and ornithine aminotransferase in rats with a portacaval shunt. The portacaval shunt caused a marked decrease in glutamine synthetase activity and an increase in ornithine aminotransferase activity. Immunohistochemical analysis showed that the glutamine synthetase and ornithine aminotransferase proteins maintained their location in the perivenous cells. These results indicate that there is no generalized loss of perivenous hepatocytes, but rather, there is a significant alteration in the expression of these proteins and hence metabolism in this cell population.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):362-8.
• Article: Beneficial effect of flax seeds in streptozotocin (STZ) induced diabetic mice: isolation of active fraction having islet regenerative and glucosidase inhibitory properties.

  Menakshi Bhat Dusane, Bimba N Joshi
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  ABSTRACT: Diabetes mellitus is a metabolic disorder that affects millions of people worldwide. Present study highlights the antidiabetogenic property of Linum usitassimum active fraction (LU6) in streptozotocin (STZ) induced diabetic Swiss mice. Treatment with LU6 fraction showed improved glucose utilization with increase in liver glucose-6-phosphate dehydrogenase enzyme activity and normal glycogenesis in hepatic and muscle tissues. Reduction in pancreatic and intestinal glucosidase inhibitory activity was observed with LU6 treatment, indicating beneficial effects in reducing postprandial hyperglycemia (PPHG). Normalization of plasma insulin and C-peptide levels were observed in diabetic mice, indicating endogenous insulin secretion after the treatment with LU6. The histochemical and immunohistochemical analysis on pancreatic islets suggests the role of LU6 fraction in islet regeneration and insulin secretion as evident in increase functional pancreatic islets producing insulin. Furthermore, significant insulin producing islet formation was also observed in in vitro PANC-1 cells after LU6 treatment, indicating the cellular aggregates to be newly formed islets. This suggests the potential of LU6 fraction in the formation of new islets in vitro, as well as in vivo. Thus, LU6 can be used as a neutraceutical-based first-line treatment for diabetes.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):325-31.
• Article: Quercetin prevents experimental glucocorticoid-induced osteoporosis: a comparative study with alendronate.

  Hoda Derakhshanian, Mahmoud Djalali, Abolghassem Djazayery, Keramat Nourijelyani, Sajad Ghadbeigi, Hamideh Pishva, Ahmad Saedisomeolia, Arash Bahremand, Ahmad Reza Dehpour
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  ABSTRACT: Glucocorticoid-induced osteoporosis (GIO) is the most common type of secondary osteoporosis. The aim of this study was to compare the efficacy of quercetin, a plant-derived flavonoid, with alendronate in the prevention of GIO. Fifty-six Sprague-Dawley rats were randomly distributed among 7 groups (8 rats per group) and treated for 6 weeks with one of the following: (i) normal saline; (ii) 40 mg methylprednisolone sodium succinate (MP)/kg body mass; (iii) MP + 40 μg alendronate/kg; (iv) MP + 50 mg quercetin/kg; (v) MP + 40 μg alendronate/kg + 50 mg quercetin/kg; (vi) MP + 150 mg quercetin/kg; and (vii) MP + 40 μg alendronate/kg + 150 mg quercetin/kg. MP and alendronate were injected subcutaneously and quercetin was administered by oral gavage 3 days a week. At the end of the study, femur breaking strength was significantly decreased as a consequence of MP injection. This decrease was completely compensated for in groups receiving 50 mg quercetin/kg plus alendronate, and 150 mg quercetin/kg with or without alendronate. Quercetin noticeably elevated osteocalcin as a bone formation marker, while alendronate did not show such an effect. In addition, administration of 150 mg quercetin/kg increased femoral trabecular and cortical thickness by 36% and 22%, respectively, compared with the MP-treated group. These data suggest that 150 mg quercetin/kg, alone or in combination with alendronate, can completely prevent GIO through its bone formation stimulatory effect.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):380-5.
• Article: NCS 613 exhibits anti-inflammatory effects on PBMCs from lupus patients by inhibiting p38 MAPK and NF-κB signalling pathways while reducing proinflammatory cytokine production.

  Issaka Yougbaré, Gilles Boire, Michelle Roy, Claire Lugnier, Eric Rouseau
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  ABSTRACT: Systemic lupus erythematosus (SLE) is a polymorphic and multigenic autoimmune disease that evolves into progressive and chronic inflammation of multiple joints and organs. Phosphorylation and activation of p38 MAPK, along with the resulting overproduction of interleukin (IL)-1β, IL-6, and tumour necrosis factor (TNF)-α is a hallmark of inflammatory disorders. Here, we investigated the anti-inflammatory pathway modulated by NCS 613, a specific PDE4 inhibitor, on human peripheral blood mononuclear cells (PBMCs) from 5 healthy donors and 12 SLE patients. PDE4 subtypes, p38 MAPK, and IκBα protein levels were analyzed by Western blot, while NF-κB and PDE4B immunostaining was assessed in control and lipopolysaccharide (LPS) -pretreated PBMCs. Proinflammatory cytokines were quantified by ELISA, while IL-1β mRNA was resolved by RT-qPCR. NCS 613 treatment decreased PDE4B and upregulated PDE4C in human PBMCs from healthy donors and SLE patients. LPS stimulation increased p38 MAPK phosphorylation and NF-κB translocation to the nucleus, which was abolished by NCS 613 treatment. Concomitantly, NCS 613 restored IκBα detection levels in human PBMCs from both healthy donors and SLE patients. This compound also abolished LPS-induced inflammation in PBMCs by reducing IL-6, IL-8, and TNF-α cytokines. NCS 613 is a small molecule displaying anti-inflammatory properties that may provide an alternative or complementary strategy for SLE management.
  Canadian Journal of Physiology and Pharmacology 05/2013; 91(5):353-61.
• Article: Triton X-100 inhibits L-type voltage-operated calcium channels.

  Deepak Narang, Paul M Kerr, Jason Baserman, Raymond Tam, Wei Yang, Gavin Searle, Jocelyn E Manning-Fox, Isabelle M Paulsen, Janna L Kozuska, Patrick E Macdonald, Peter E Light, Andrew Holt, Frances Plane
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  ABSTRACT: Triton X-100 (TX-100) is a nonionic detergent frequently used at millimolar concentrations to disrupt cell membranes and solubilize proteins. At low micromolar concentrations, TX-100 has been reported to inhibit the function of potassium channels. Here, we have used electrophysiological and functional techniques to examine the effects of TX-100 on another class of ion channels, L-type voltage-operated calcium channels (VOCCs). TX-100 (30 nmol·L(-1) to 3 μmol·L(-1)) caused reversible concentration-dependent inhibition of recombinant L-type VOCC (CaV 1.2) currents and of native L-type VOCC currents recorded from rat vascular smooth muscle cells and cardiac myocytes, and murine and human pancreatic β-cells. In functional studies, TX-100 (165 nmol·L(-1) to 3.4 μmol·L(-1)) caused concentration-dependent relaxation of rat isolated mesenteric resistance arteries prestimulated with phenylephrine or KCl. This effect was independent of the endothelium. TX-100 (1.6 μmol·L(-1)) inhibited depolarization-induced exocytosis in both murine and human isolated pancreatic β-cells. These data indicate that at concentrations within the nanomolar to low micromolar range, TX-100 significantly inhibits L-type VOCC activity in a number of cell types, an effect paralleled by inhibition of cell functions dependent upon activation of these channels. This inhibition occurs at concentrations below those used to solubilize proteins and may compromise the use of solutions containing TX-100 in bioassays.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):316-24.
• Article: Involvement of mixed lineage kinase 3 in cancer.

  Deborah N Chadee
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  ABSTRACT: Mitogen-activated protein kinase (MAPK) signaling pathways are composed of a phosphorelay signaling module where an activated MAP kinase kinase kinase (MAP3K) phosphorylates and activates a MAPK kinase (MAP2K) that in turn phosphorylates and activates a MAPK. The biological outcome of MAPK signaling is the regulation of cellular responses such as proliferation, differentiation, migration, and apoptosis. The MAP3K mixed lineage kinase 3 (MLK3) phosphorylates MAP2Ks to activate multiple MAPK signaling pathways, and MLK3 also has functions in cell signaling that are independent of its kinase activity. The recent elucidation of essential functions for MLK3 in tumour cell proliferation, migration, and invasion has drawn attention to the MLKs as potential therapeutic targets for cancer treatments. The mounting evidence that suggests a role for MLK3 in tumourigenesis and establishment of the malignant phenotype is the focus of this review.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):268-74.
• Article: The evolution of nutrition research.

  Cara K Isaak, Yaw L Siow
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  ABSTRACT: "The doctor of the future will no longer treat the human frame with drugs, but will rather cure and prevent disease with nutrition". Thomas Edison's contemplation may come to fruition if the nutritional revolution continues in its current course. Two realizations have propelled the world into a new age of personalized nutrition: (i) food can provide benefits beyond its intrinsic nutrient content, and (ii) we are not all created equal in our ability to realize to these benefits. Nutrigenomics is concerned with delineating genomic propensities to respond to various nutritional stimuli and the resulting impact on individual health. This review will examine the current technologies utilized by nutrigeneticists, the available literature regarding nutrient-gene interactions, and the translation of this new awareness into public health.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):257-67.
• Article: Inflammatory cytokine TNF-α inhibits Na(+)-glutamine cotransport in intestinal epithelial cells.

  Jamilur R Talukder, Brittney Boyd, Ashley Griffin, Antara Jaima, Vazhaikkurichi M Rajendran
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  ABSTRACT: Glutamine (Gln), a preferred fuel source for enterocytes, is critical for intestinal epithelial cell integrity and barrier function. Chronic enteritis inhibits apical Na(+)-Gln cotransport. It is not known whether inflammatory cytokines that are secreted during inflammation inhibit Na(+)-Gln cotransport. Thus, this study aimed to examine whether TNF-α would affect apical Na(+)-Gln cotransport in intestinal epithelial cells. In this study, the presence of Na(+)-Gln cotransport was established by measuring Gln uptake in 10 days postconfluent IEC-6 cells grown on transwell plates. Cation, amino acid specificity, and siRNA transfection studies established that Na(+)-Gln cotransport is mediated via B(0)AT1. Immunoblotting and immunofluorescence studies established the apical membrane localization of B(0)AT1 in IEC-6 cells. Tumour necrosis factor α (TNF-α) inhibited Na(+)-Gln cotransport in a concentration- and time-dependent manner with an inhibitory concentration of 1.53 nmol·L(-1). Quantitative real-time PCR and Western blot analyses indicated that TNF-α did not alter B(0)AT1-specific transcripts or protein expression level. Kinetic studies revealed that TNF-α inhibited Na(+)-Gln cotransport by reducing the affinity of the cotransporters for Gln, and this effect was antagonized by genistein. Thus, we conclude that the TNF-α inhibition of Na(+)-Gln cotransport occurs at the post-translational level, and that the IEC-6 cell line is an excellent system to study the role of cytokines in Na(+)-Gln cotransport.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):275-84.
• Article: Mepivacaine-induced contraction involves phosphorylation of extracellular signal-regulated kinase through activation of the lipoxygenase pathway in isolated rat aortic smooth muscle.

  Hyo Min Lee, Seong-Ho Ok, Hui-Jin Sung, So Young Eun, Hye Jung Kim, Soo Hee Lee, Sebin Kang, Il-Woo Shin, Heon Keun Lee, Young-Kyun Chung, Mun-Jeoung Choi, Sung Il Bae, Ju-Tae Sohn
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  ABSTRACT: Mepivacaine is an aminoamide local anesthetic with an intermediate duration that intrinsically produces vasoconstriction both in vivo and in vitro. This study investigated the arachidonic acid metabolic pathways involved in mepivacaine-induced contraction, and elucidated the associated cellular mechanism with a particular focus on extracellular signal-regulated kinase (ERK) in endothelium-denuded rat aorta. Isolated rat thoracic aortic rings were suspended for isometric tension recording. Cumulative mepivacaine concentration-response curves were generated in the presence or absence of the following inhibitors: quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, indomethacin, NS-398, SC-560, fluconazole, PD 98059, and verapamil. Mepivacaine-induced ERK phosphorylation, 5-lipoxygenase (5-LOX) expression, and cyclooxygenase (COX)-2 expression in rat aortic smooth muscle cells were detected by Western blot analysis in the presence or absence of inhibitors. Mepivacaine produced tonic contraction in isolated endothelium-denuded rat aorta. Quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, NS-398, PD 98059, and verapamil attenuated mepivacaine-induced contraction in a concentration-dependent manner. However, fluconazole had no effect on mepivacaine-induced contraction. PD 98059, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA-861, phenidone, and indomethacin attenuated mepivacaine-induced ERK phosphorylation. Mepivacaine upregulated 5-LOX and COX-2 expression. These results suggest that mepivacaine-induced contraction involves ERK activation, which is primarily mediated by the 5-LOX pathway and in part by the COX-2 pathway.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):285-94.
• Article: Quinidine elicits proarrhythmic changes in ventricular repolarization and refractoriness in guinea-pig.

  Oleg E Osadchii
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  ABSTRACT: Quinidine is a class Ia Na(+) channel blocker that prolongs cardiac repolarization owing to the inhibition of IKr, the rapid component of the delayed rectifier current. Although quinidine may induce proarrhythmia, the contributing mechanisms remain incompletely understood. This study examined whether quinidine may set proarrhythmic substrate by inducing spatiotemporal abnormalities in repolarization and refractoriness. The monophasic action potential duration (APD), effective refractory periods (ERPs), and volume-conducted electrocardiograms (ECGs) were assessed in perfused guinea-pig hearts. Quinidine was found to produce the reverse rate-dependent prolongation of ventricular repolarization, which contributed to increased steepness of APD restitution. Throughout the epicardium, quinidine elicited a greater APD increase in the left ventricular chamber compared with the right ventricle, thereby enhancing spatial repolarization heterogeneities. Quinidine prolonged APD to a greater extent than ERP, thus extending the vulnerable window for ventricular re-excitation. This change was attributed to increased triangulation of epicardial action potential because of greater APD lengthening at 90% repolarization than at 30% repolarization. Over the transmural plane, quinidine evoked a greater ERP prolongation at endocardium than epicardium and increased dispersion of refractoriness. Premature ectopic beats and monomorphic ventricular tachycardia were observed in 50% of quinidine-treated heart preparations. In summary, abnormal changes in repolarization and refractoriness contribute greatly to proarrhythmic substrate upon quinidine infusion.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):306-15.
• Article: Effects of chronic in-vivo treatments with protease-activated receptor 2 agonist on endothelium function and blood pressures in mice.

  Keon H Hughes, Enoka P Wijekoon, James E Valcour, Elizabeth W Chia, John J McGuire
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  ABSTRACT: Short-term treatments with protease-activated receptor 2-activating peptides (PAR2-AP) induce endothelium-dependent vasodilation and decrease blood pressure. In this study, we tested the effect of chronic in-vivo treatment with PAR2-AP on the blood pressure and endothelium function of mice. Male PAR2 wild-type (WT) and par2-deficient (KO) mice received subcutaneous infusions of either saline, low (PAR2-LD), or high (PAR2-HD) doses of 2-furoyl-LIGRLO-amide for 1 or 2 weeks. In each treatment group, endothelium function was assessed in isolated arteries. Blood pressure, heart rate, and locomotor activity were recorded by radiotelemetry, and levels of tumour nercrosis factor α (TNF-α) and interkeukin 1β (IL-1β) were measured in plasma samples by ELISA. The relaxation of WT aortas and mesenteric arteries induced by PAR2-AP was decreased by PAR2-LD and PAR2-HD. In mesenteric arteries, PAR2-LD and PAR2-HD decreased the relaxation induced by acetylcholine, but not by nitroprusside; in aortas, PAR2-LD and PAR2-HD caused differential decreases in the relaxations induced by acetylcholine and nitroprusside. Only PAR2-HD lowered systolic arterial pressures in WT, when compared with all of the other groups. TNF-α and IL-1β plasma concentrations were not different among the groups. We conclude that the systolic blood pressure of unrestrained mice can be lowered by chronic in-vivo activation of PAR2; however, this effect is countered by receptor desensitization and the concomitant development of endothelium and vascular dysfunction.
  Canadian Journal of Physiology and Pharmacology 04/2013; 91(4):295-305.
• Article: The effect of 25-hydroxyvitamin D on insulin sensitivity in obesity: is it mediated via adiponectin?

  Olivia R.L Wright, Ingrid J Hickman, William Petchey, Clair Sullivan, Cynthia Ong, Felicity J. Rose, Johannes B. Prins, Jonathan P Whitehead, Trisha M. O'Moore-Sullivan
  Canadian Journal of Physiology and Pharmacology 03/2013;
• Article: Insulin-like growth-factor-1-induced PKB signaling and Egr-1 expression is inhibited by curcumin in A-10 vascular smooth muscle cells.

  Viktoria Youreva, Georgia Kapakos, Ashok K Srivastava
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  ABSTRACT: Insulin-like growth factor 1 (IGF-1) is a mitogenic factor that stimulates the signaling pathways responsible for inducing hypertrophic and proliferative responses in vascular smooth muscle cells (VSMC). We have previously demonstrated that IGF-1 receptor (IGF-1R) plays a key role in transducing the hypertrophic and proliferative responses of angiotensin II (Ang-II) and endothelin-1 (ET-1). Curcumin, a polyphenolic compound derived from the spice turmeric is known to possess antiproliferative properties and exerts vasculoprotective effects. However, the ability of curcumin to modulate IGF-1-induced signaling responses in VSMC remains to be investigated. In this study, we determined the effect of curcumin on IGF-1-induced phosphorylation of protein kinase B (PKB), glycogen synthase kinase-3β (GSK-3β), and IGF-1R in VSMC. Curcumin inhibited IGF-1-induced phosphorylation of PKB and GSK-3β as well as the IGF-1R β subunit in a dose-dependent fashion. In addition, IGF-1-induced expression of early growth response protein 1 (Egr-1) which plays a pathogenic role in vascular dysfunctions, was also attenuated by curcumin. In conclusion, these results indicate that curcumin is a potent inhibitor of key components of the IGF-1-induced mitogenic and proliferative signaling system in VSMC, and suggest that curcumin-induced attenuation of these signaling components may constitute a potential mechanism for its vasculoprotective effects.
  Canadian Journal of Physiology and Pharmacology 03/2013; 91(3):241-7.
• Article: Modeling xenobiotic susceptibility to hepatotoxicity using an in vitro oxidative stress inflammation model.

  Stephanie L Macallister, Abdullah A Maruf, Luke Wan, Erin Chung, Peter O'Brien
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  ABSTRACT: Evidence suggests xenobiotic exposure during periods of inflammation can increase an individual's susceptibility to toxicity. The present study aimed to validate an in-vitro inflammatory model to identify compounds that increase hepatotoxicity during inflammation. Using freshly isolated hepatocytes exposed to a low nontoxic flow of H2O2 using glucose (G) and glucose oxidase (GO) and supplementing it with either peroxidase or Fe(II), the effects of inflammation on 2 classes of drugs known to cause hepatotoxicity were examined: nitroaromatics (nimesulide, nilutamide, flutamide) and aromatic amines (clozapine, thioridazine). Co-incubation with G/GO and the nitroaromatics increased toxicity that was further increased when peroxidase was present. While the aromatic amines did not increase cytotoxicity with G/GO alone, they demonstrated significant increases in cytotoxicity when incubated with peroxidase+G/GO. Liver injury is commonly observed with alcohol abusers; therefore, the effects of inflammation on ethanol, and its metabolite acetaldehyde, were observed. Both ethanol and acetaldehyde increased cytotoxicity, which was further increased when Fe(II) was present. These results implicate H2O2, a cellular mediator of inflammation, as a potential risk factor for hepatotoxicity. A H2O2-enhanced hepatocyte-system in the presence of peroxidase or Fe(II) may prove useful for a more robust screening of xenobiotics for assessing potential toxicity associated with inflammation.
  Canadian Journal of Physiology and Pharmacology 03/2013; 91(3):236-40.
• Article: The antioxidant resveratrol down-regulates inflammation in an in-vitro model of Pseudomonas aeruginosa infection of lung epithelial cells.

  Ashley M Cerqueira, Neelam Khaper, Simon J Lees, Marina Ulanova
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  ABSTRACT: Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that can cause severe pulmonary infection in immunocompromized individuals. During the infectious process, P. aeruginosa provokes a potent inflammatory response and induces the release of reactive oxygen species (ROS). Cells undergo oxidative stress when cellular antioxidants are unable to effectively scavenge and detoxify ROS, resulting in lung damage. Resveratrol (3,5,4'-trihydroxystilbene) is a natural polyphenolic compound with recognized antioxidant effects. We hypothesized that owing to its antioxidant activities, resveratrol can attenuate an inflammatory response in P. aeruginosa-infected cells. Lung epithelial A549 cells were pre-treated with 100 μmol/L of resveratrol for 5 h, followed by infection with P. aeruginosa. Intracellular ROS generation was used as an indicator of P. aeruginosa-induced oxidative stress, and cell surface expression of Fas receptor and activation of caspases-3 and -7 as indicators of apoptosis. We also measured the surface expression of intercellular adhesion molecule (ICAM)-1 and enzymes related to inflammation and redox signaling. Resveratrol significantly reduced ROS generation, ICAM-1, and human beta-defensin-2 expression, as well as the markers of apoptosis in A549 cells infected with P. aeruginosa, and up-regulated glutathione peroxidase, suggesting its potential therapeutic role in protecting the lungs against the deleterious effects of P. aeruginosa infection.
  Canadian Journal of Physiology and Pharmacology 03/2013; 91(3):248-55.