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Fender A.C.,Heinrich Heine University Dusseldorf | Pavic G.,Heinrich Heine University Dusseldorf | Drummond G.R.,Monash University | Dusting G.J.,University of Melbourne | Ritchie R.H.,Baker IDI Heart Research Institute
Naunyn-Schmiedeberg's Archives of Pharmacology | Year: 2014

Activators of protease-activated receptors PAR-1 and PAR-2 such as thrombin and synthetic hexapeptides promote hypertrophy of isolated neonatal cardiomyocytes at pathological concentrations. Since PAR-activating proteases often show dual actions at low vs. high concentrations, the potential hypertrophic effects of low-level PAR activation were examined. In H9c2 cardiomyoblasts, messenger RNA (mRNA) expression of the hypertrophic marker atrial natriuretic peptide (ANP) was significantly increased only by higher concentrations of thrombin, trypsin or the synthetic PAR-2 agonist SLIGRL. The dual PAR-1/PAR-2 agonist SFLLRN did not influence basal ANP mRNA expression in H9c2 cells. Low concentration of thrombin or trypsin (up to 0.1 U/mL) or of the synthetic ligands SFLLRN and SLIGRL (1 μM); however, all suppressed ANP mRNA expression stimulated by angiotensin II (Ang II). The PAR-1 selective ligand TFLLRN exerted a comparable effect as SFLLRN. In adult rat cardiomyocytes, protein synthesis determined by [3H]phenylalanine incorporation was not increased by various PAR agonists at concentrations tenfold lower than conventionally used to study PAR function in vitro (10 μM for SFLLRN or SLIGRL, 0.1 U/mL for thrombin or trypsin). The positive control endothelin-1 (ET-1, 60 nM) however significantly increased protein synthesis in adult rat cardiomyocytes. Addition of low concentrations of PAR agonists to cardiomyocytes treated with ET-1 or Ang II suppressed [3H]phenylalanine incorporation induced by the hypertrophic stimuli. The inhibitory effect of SFLLRN effect was partially reversed by the PAR-1 antagonist RWJ56110. These findings suggest that physiological concentrations of PAR activators may suppress hypertrophy, in contrast to the pro-hypertrophic effects evident at high concentrations. PAR-1 and PAR-2 may dynamically control cardiomyocyte growth, with the net effect critically dependent upon local agonist concentrations. The precise significance of proposed concept of bimodal PAR function in cardiomyocytes remains to be defined, particularly in vivo where hemodynamic and other regulatory factors may counteract or mask the direct cellular actions described here. © 2014 Springer-Verlag Berlin Heidelberg. Source

Lambers Heerspink H.J.,University of Sydney | Lambers Heerspink H.J.,University of Groningen | Ninomiya T.,University of Sydney | Perkovic V.,University of Sydney | And 10 more authors.
European Heart Journal | Year: 2010

AimsIndividuals with diabetes and chronic kidney disease (CKD) are at high risk for cardiovascular disease. In these analyses of the ADVANCE trial, we assessed the effects of a fixed combination of perindopril-indapamide on renal and cardiovascular outcomes in patients with type 2 diabetes according to baseline CKD stage. Methods and resultsPatients with type 2 diabetes were randomized to perindopril-indapamide (4 mg/1.25 mg) or placebo. Treatment effects on cardiovascular (cardiovascular death, myocardial infarction, or stroke) and renal outcomes were compared in subgroups defined by baseline Kidney Disease Outcome Quality Initiative CKD stage. Homogeneity in treatment effect was tested by adding interaction terms to the relevant Cox models. The study included 10 640 participants with known CKD status, of whom 6125 did not have CKD, 2482 were classified as CKD stage 1 or 2, and 2033 as CKD stage ≥3. The relative treatment effects on major cardiovascular events were similar across all stages of CKD, with no heterogeneity in the magnitude of the effects for any outcome. In contrast, the absolute treatment effects approximately doubled in those with CKD stage ≥3 when compared to those with no CKD. For every 1000 patients with CKD stage ≥3 treated for 5 years, active treatment prevented 12 cardiovascular events when compared with six events per 1000 patients with no CKD. ConclusionThe treatment benefits of a routine administration of a fixed combination of perindopril-indapamide to patients with type 2 diabetes on cardiovascular and renal outcomes, and death, are consistent across all stages of CKD at baseline. Absolute risk reductions are larger in patients with CKD highlighting the importance of blood pressure-lowering in this population. © 2010 The European Society of Cardiology . All rights reserved. Source

Marques F.Z.,University of Sydney | Campain A.E.,University of Sydney | Davern P.J.,Baker IDI Heart Research Institute | Yang Y.H.J.,University of Sydney | And 2 more authors.
PLoS ONE | Year: 2011

Essential hypertension is a common multifactorial heritable condition in which increased sympathetic outflow from the central nervous system is involved in the elevation in blood pressure (BP), as well as the exaggerated morning surge in BP that is a risk factor for myocardial infarction and stroke in hypertensive patients. The Schlager BPH/2J mouse is a genetic model of hypertension in which increased sympathetic outflow from the hypothalamus has an important etiological role in the elevation of BP. Schlager hypertensive mice exhibit a large variation in BP between the active and inactive periods of the day, and also show a morning surge in BP. To investigate the genes responsible for the circadian variation in BP in hypertension, hypothalamic tissue was collected from BPH/2J and normotensive BPN/3J mice at the 'peak' (n = 12) and 'trough' (n = 6) of diurnal BP. Using Affymetrix GeneChip® Mouse Gene 1.0 ST Arrays, validation by quantitative real-time PCR and a statistical method that adjusted for clock genes, we identified 212 hypothalamic genes whose expression differed between 'peak' and 'trough' BP in the hypertensive strain. These included genes with known roles in BP regulation, such as vasopressin, oxytocin and thyrotropin releasing hormone, as well as genes not recognized previously as regulators of BP, including chemokine (C-C motif) ligand 19, hypocretin and zinc finger and BTB domain containing 16. Gene ontology analysis showed an enrichment of terms for inflammatory response, mitochondrial proton-transporting ATP synthase complex, structural constituent of ribosome, amongst others. In conclusion, we have identified genes whose expression differs between the peak and trough of 24-hour circadian BP in BPH/2J mice, pointing to mechanisms responsible for diurnal variation in BP. The findings may assist in the elucidation of the mechanism for the morning surge in BP in essential hypertension. © 2011 Marques et al. Source

Marques F.Z.,Robert Bosch GmbH | Campain A.E.,University of Sydney | Davern P.J.,Baker IDI Heart Research Institute | Yang Y.H.J.,University of Sydney | And 2 more authors.
Physiological Genomics | Year: 2011

The hypothalamus has an important etiological role in the onset and maintenance of hypertension and stress responses in the Schlager high blood pressure (BP) (BPH/2J) mouse, a genetic model of neurogenic hypertension. Using Affymetrix GeneChip Mouse Gene 1.0 ST Arrays we identified 1,019 hypothalamic genes whose expression differed between 6 wk old BPH/2J and normal BP (BPN/3J) strains, and 466 for 26 wk old mice. Of these, 459 were in 21 mouse BP quantitative trait loci. We validated 46 genes by qPCR. Gene changes that would increase sympathetic outflow at both ages were: Dynll1 encoding dynein light chain LC8-type 1, which physically destabilizes neuronal nitric oxide synthase, decreasing neuronal nitric oxide, and Hcrt encoding hypocretin and Npsr1 encoding neuropeptide S receptor 1, each involved in sympathetic response to stress. At both ages we identified genes for inflammation, such as CC-chemokine ligand 19 (Ccl19), and oxidative stress. Via reactive oxygen species generation, these could contribute to oxidative damage. Other genes identified could be responding to such perturbations. Atp2b1, the major gene from genome-wide association studies of BP variation, was underexpressed in the early phase. Comparison of profiles of young and adult BPH/2J mice, after adjusting for maturation genes, pointed to the proopiomelanocortin-_ gene (Pomc) and neuropeptide Y gene (Npy), among others, as potentially causative. The present study has identified a diversity of genes and possible mechanisms involved in hypertension etiology and maintenance in the hypothalamus of BPH/2J mice, highlighting both common and divergent processes in each phase of the condition. © 2011 the American Physiological Society. Source

Sourris K.C.,Baker IDI Heart Research Institute | Sourris K.C.,Monash University | Harcourt B.E.,Baker IDI Heart Research Institute | Harcourt B.E.,Monash University | And 15 more authors.
Free Radical Biology and Medicine | Year: 2012

Cardiovascular benefits of ubiquinone have been previously demonstrated, and we administered it as a novel therapy in an experimental model of type 2 diabetic nephropathy. db/db and dbH mice were followed for 10 weeks, after randomization to receive either vehicle or ubiquinone (CoQ10; 10 mg/kg/day) orally. db/db mice had elevated urinary albumin excretion rates and albumin:creatinine ratio, not seen in db/db CoQ10-treated mice. Renal cortices from db/db mice had lower total and oxidized CoQ10 content, compared with dbH mice. Mitochondria from db/db mice also contained less oxidized CoQ10(ubiquinone) compared with dbH mice. Diabetes-induced increases in total renal collagen but not glomerulosclerosis were significantly decreased with CoQ10 therapy. Mitochondrial superoxide and ATP production via complex II in the renal cortex were increased in db/db mice, with ATP normalized by CoQ10. However, excess renal mitochondrial hydrogen peroxide production and increased mitochondrial membrane potential seen in db/db mice were attenuated with CoQ10. Renal superoxide dismutase activity was also lower in db/db mice compared with dbH mice. Our results suggest that a deficiency in mitochondrial oxidized CoQ10 (ubiquinone) may be a likely precipitating factor for diabetic nephropathy. Therefore CoQ10 supplementation may be renoprotective in type 2 diabetes, via preservation of mitochondrial function. © 2011 Elsevier Inc. © 2011 Elsevier Inc. All rights reserved. Source

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