scholarly journals NOX Inhibition Improves β-Adrenergic Stimulated Contractility and Intracellular Calcium Handling in the Aged Rat Heart

2018 ◽  
Vol 19 (8) ◽  
pp. 2404 ◽  
Author(s):  
Álvaro Valdés ◽  
Adriana Treuer ◽  
Guillermo Barrios ◽  
Nikol Ponce ◽  
Roberto Fuentealba ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Intracellular Calcium ◽  
Negative Impact ◽  
Calcium Handling ◽  
Isolated Cardiomyocytes ◽  
Isolated Hearts ◽  
Nox Inhibitors ◽  
Isolated Cardiac Myocytes ◽  
Old Rats ◽  
Phospholamban Phosphorylation

Cardiac aging is characterized by alterations in contractility and intracellular calcium ([Ca2+]i) homeostasis. It has been suggested that oxidative stress may be involved in this process. We and others have reported that in cardiomyopathies the NADPH oxidase (NOX)-derived superoxide is increased, with a negative impact on [Ca2+]i and contractility. We tested the hypothesis that in the aged heart, [Ca2+]i handling and contractility are disturbed by NOX-derived superoxide. For this we used adults (≈5 month-old) and aged (20–24 month-old) rats. Contractility was evaluated in isolated hearts, challenged with isoproterenol. To assess [Ca2+]i, isolated cardiac myocytes were field-stimulated and [Ca2+]i was monitored with fura-2. Cardiac concentration-response to isoproterenol was depressed in aged compared to adults hearts (p < 0.005), but was restored by NOX inhibitors apocynin and VAS2870. In isolated cardiomyocytes, apocynin increased the amplitude of [Ca2+]i in aged myocytes (p < 0.05). Time-50 [Ca2+]i decay was increased in aged myocytes (p < 0.05) and reduced towards normal by NOX inhibition. In addition, we found that myofilaments Ca2+ sensitivity was reduced in aged myocytes (p < 0.05), and was further reduced by apocynin. NOX2 expression along with NADPH oxidase activity was increased in aged hearts. Phospholamban phosphorylation (Ser16/Thr17) after isoproterenol treatment was reduced in aged hearts compared to adults and was restored by apocynin treatment (p < 0.05). In conclusion, β-adrenergic-induced contractility was depressed in aged hearts, and NOX inhibition restored back to normal. Moreover, altered Ca2+ handling in aged myocytes was also improved by NOX inhibition. These results suggest a NOX-dependent effect in aged myocytes at the level of Ca2+ handling proteins and myofilaments.

scholarly journals NOX Inhibition Improves β Adrenergic-Stimulated Contractility and Intracellular Calcium Handling in the Aged Heart

2018 ◽  
Author(s):  
Alvaro Valdés ◽  
Guillermo Barrios ◽  
Nikol Ponce ◽  
Raul A Dulce ◽  
Daniel R Gonzalez
Keyword(s):  
Oxidative Stress ◽  
Intracellular Calcium ◽  
Negative Impact ◽  
Calcium Handling ◽  
Isolated Cardiomyocytes ◽  
Beta Adrenergic ◽  
Dependent Effect ◽  
Isolated Hearts ◽  
Nox Inhibitors ◽  
Isolated Cardiac Myocytes

Cardiac aging is characterized by alterations in contractility and intracellular calcium ([Ca2+]i) homeostasis. It has been suggested that oxidative stress may be involved in this process. We and others have reported that in cardiomyopathies the NADPH oxidase (NOX)-derived superoxide is increased, with a negative impact on [Ca2+]i and contractility. We tested the hypothesis that in the aged heart, [Ca2+]i handling and contractility are disturbed by NOX-derived superoxide. Contractility was evaluated isolated hearts, challenged with isoproterenol. To assess [Ca2+]i, isolated cardiac myocytes were field-stimulated and [Ca2+]i was monitored with fura-2. Cardiac concentration-response to isoproterenol was depressed in aged compared to adults hearts (p &lt; 0.005), but was restored by NOX inhibitors apocynin and VAS2870. In isolated cardiomyocytes, apocynin increased the amplitude of [Ca2+]i in aged myocytes (p &lt; 0.05). Time-50 [Ca2+]i decay was increased in aged myocytes (p &lt; 0.05) and reduced towards normal by NOX inhibition. In addition, we found that myofilaments Ca2+ sensitivity was reduced in aged myocytes (p &lt; 0.05), and further reduced by apocynin. Finally SERCA levels but not phospholamban were reduced in aged hearts (p &lt; 0.05). In conclusion, &beta;-adrenergic‒induced contractility was depressed in aged hearts, and NOX inhibition restored back to normal. Moreover, altered Ca2+ handling in aged myocytes was also improved by NOX inhibition. These results suggest a NOX-dependent effect in aged myocytes at the level of Ca2+ handling proteins and myofilaments.

scholarly journals NADPH oxidase-2 inhibition restores contractility and intracellular calcium handling and reduces arrhythmogenicity in dystrophic cardiomyopathy

2014 ◽  
Vol 307 (5) ◽  
pp. H710-H721 ◽  
Author(s):  
Daniel R. Gonzalez ◽  
Adriana V. Treuer ◽  
Guillaume Lamirault ◽  
Vera Mayo ◽  
Yenong Cao ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Calcium Release ◽  
Calcium Handling ◽  
Mdx Mouse ◽  
No Production ◽  
Wild Type ◽  
Intracellular Ca ◽  
Dystrophic Cardiomyopathy ◽  
The Impact ◽  
Phospholamban Phosphorylation

Duchenne muscular dystrophy may affect cardiac muscle, producing a dystrophic cardiomyopathy in humans and the mdx mouse. We tested the hypothesis that oxidative stress participates in disrupting calcium handling and contractility in the mdx mouse with established cardiomyopathy. We found increased expression (fivefold) of the NADPH oxidase (NOX) 2 in the mdx hearts compared with wild type, along with increased superoxide production. Next, we tested the impact of NOX2 inhibition on contractility and calcium handling in isolated cardiomyocytes. Contractility was decreased in mdx myocytes compared with wild type, and this was restored toward normal by pretreating with apocynin. In addition, the amplitude of evoked intracellular Ca2+ concentration transients that was diminished in mdx myocytes was also restored with NOX2 inhibition. Total sarcoplasmic reticulum (SR) Ca2+ content was reduced in mdx hearts and normalized by apocynin treatment. Additionally, NOX2 inhibition decreased the production of spontaneous diastolic calcium release events and decreased the SR calcium leak in mdx myocytes. In addition, nitric oxide (NO) synthase 1 (NOS-1) expression was increased eightfold in mdx hearts compared with wild type. Nevertheless, cardiac NO production was reduced. To test whether this paradox implied NOS-1 uncoupling, we treated cardiac myocytes with exogenous tetrahydrobioterin, along with the NOX inhibitor VAS2870. These agents restored NO production and phospholamban phosphorylation in mdx toward normal. Together, these results demonstrate that, in mdx hearts, NOX2 inhibition improves the SR calcium handling and contractility, partially by recoupling NOS-1. These findings reveal a new layer of nitroso-redox imbalance in dystrophic cardiomyopathy.

scholarly journals Liraglutide Preserves Intracellular Calcium Handling in Isolated Murine Myocytes Exposed to Oxidative Stress

2017 ◽  
pp. 889-895 ◽  
Author(s):  
S. PALEE ◽  
S. C. CHATTIPAKORN ◽  
N. CHATTIPAKORN
Keyword(s):  
Oxidative Stress ◽  
Decay Rate ◽  
Intracellular Calcium ◽  
Wistar Rats ◽  
Calcium Handling ◽  
Isolated Cardiomyocytes ◽  
Before And After ◽  
Male Wistar Rats ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

In ischemic/reperfusion (I/R) injured hearts, severe oxidative stress occurs and is associated with intracellular calcium (Ca2+) overload. Glucagon-Like Peptide-1 (GLP-1) analogues have been shown to exert cardioprotection in I/R heart. However, there is little information regarding the effects of GLP-1 analogue on the intracellular Ca2+ regulation in the presence of oxidative stress. Therefore, we investigated the effects of GLP-1 analogue, (liraglutide, 10 µM) applied before or after hydrogen peroxide (H2O2, 50 µM) treatment on intracellular Ca2+ regulation in isolated cardiomyocytes. We hypothesized that liraglutide can attenuate intracellular Ca2+ overload in cardiomyocytes under H2O2-induced cardiomyocyte injury. Cardiomyocytes were isolated from the hearts of male Wistar rats. Isolated cardiomyocytes were loaded with Fura-2/AM and fluorescence intensity was recorded. Intracellular Ca2+ transient decay rate, intracellular Ca2+ transient amplitude and intracellular diastolic Ca2+ levels were recorded before and after treatment with liraglutide. In H2O2 induced severe oxidative stressed cardiomyocytes (which mimic cardiac I/R) injury, liraglutide given prior to or after H2O2 administration effectively increased both intracellular Ca2+ transient amplitude and intracellular Ca2+ transient decay rate, without altering the intracellular diastolic Ca2+ level. Liraglutide attenuated intracellular Ca2+ overload in H2O2-induced cardiomyocyte injury and may be responsible for cardioprotection during cardiac I/R injury by preserving physiological levels of calcium handling during the systolic and diastolic phases of myocyte activation.

Synthesis and biological evaluation of 3-substituted 5-benzylidene-1-methyl-2-thiohydantoins as potent NADPH oxidase (NOX) inhibitors

2016 ◽  
Vol 24 (18) ◽  
pp. 4144-4151 ◽  
Author(s):  
Yun Soo Bae ◽  
Sun Choi ◽  
Jung Jae Park ◽  
Jung Hee Joo ◽  
Minghua Cui ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Biological Evaluation ◽  
Nox Inhibitors ◽  
Synthesis And Biological Evaluation

scholarly journals Neuromuscular junction instability and altered intracellular calcium handling as early determinants of force loss during unloading in humans

2021 ◽  
Author(s):  
Elena Monti ◽  
Carlo Reggiani ◽  
Martino V. Franchi ◽  
Luana Toniolo ◽  
Marco Sandri ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Intracellular Calcium ◽  
Calcium Handling

Abstract MP135: Cardiac Sarcoplasmic Reticulum Calcium Cycling is Regulated by Kinase Independent Function of Pi3kgamma

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Maradumane L Mohan ◽  
Conner P Witherow ◽  
Robert S Papay ◽  
Sathyamangla V Naga Prasad
Keyword(s):  
Intracellular Calcium ◽  
Calcium Release ◽  
Cardiac Contractility ◽  
Underlying Mechanism ◽  
Calcium Handling ◽  
Ventricular Contractility ◽  
Independent Function ◽  
Calcium Cycling ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Phosphoinositide 3 Kinase

Genetic deletion of Phosphoinositide 3-kinase (PI3Kγ) in mice (PI3Kγ -/- ) results in increased cAMP levels and enhanced ventricular contractility. We investigated whether the lack of PI3Kγ plays a role in cardiac contractility by altering intracellular calcium recycling. Isolated cardiomyocytes from PI3Kγ -/- mice showed significantly reduced calcium reuptake by sarcoendoplasmic reticulum (SR) following caffeine induced calcium release indicating that PI3Kγ locally regulates the function of SR. The intracellular calcium remained at elevated levels in the cardiomyocytes of PI3Kγ -/- for a prolonged period after caffeine treatment. This could be due to changes in phosphorylation of SERCA2, Ryanodine receptor (RyR 2 ) or phospholamban (PLN). In fact, when we looked at phosphorylation of PLN in cardiac lysates, a major regulator of cardiac contractility and relaxation, PI3Kγ -/- mice showed significantly reduced PLN phosphorylation compared to littermate controls. Previous studies from our laboratory suggested that absence of PI3Kγ leads to increase in protein phosphatase (PP) activity which could be possible reason for rapid dephosphorylation of PLN, resulting in inhibition of SERCA2 pump. We observed increased SR associated PP activity and PLN associated PP activity in PI3Kγ -/- mice. We also observed increased association of PP-1 and PP2A with PLN in the absence of PI3Kγ. The altered calcium handling in the cardiomyocytes of PI3Kγ -/- mice could be restored to the level of WT controls by okadaic acid mediated inhibition of PP, suggesting that PI3Kγ plays a role in regulating PP activity associated with SR. To test whether PI3Kγ activity is required for PLN dephosphorylation and SR calcium cycling, we used mice with cardiac specific overexpression of kinase dead PI3Kγ (PI3Kγ inact ) in global PI3Kγ -/- mice (PI3Kγ inact /PI3Kγ -/- ). PI3Kγ inact /PI3Kγ -/- mice showed restored PLN phosphorylation, improved caffeine induced calcium reuptake, decreased SR and PLN associated PP activity. These studies show a novel regulation of PP and SR calcium regulation by kinase independent function of PI3Kγ. The underlying mechanism of PP regulation by PI3Kγ will be presented.

P943The effects of ovariectomy on guinea pig cardiomyocyte intracellular calcium regulation and phosphorylation

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
E Ching ◽  
J M Firth ◽  
A J Francis ◽  
N Islam ◽  
K T Macleod
Keyword(s):  
Intracellular Calcium ◽  
Calcium Regulation ◽  
Left Ventricular ◽  
Calcium Handling ◽  
Time To Peak ◽  
Oestrogen Deficiency ◽  
Calcium Handling Proteins ◽  
Presence And Absence ◽  
Intracellular Calcium Regulation

Abstract Background Differences in cardiovascular disease risk between men and women have been partly attributed to the cardioprotective effects of oestrogen. Long-term oestrogen deficiency has been shown to alter cardiomyocyte intracellular calcium handling, but little is known about the mechanisms by which these changes occur. Oestrogen is thought to induce both genomic and non-genomic effects on cardiomyocytes, the latter including phosphorylation of calcium handling proteins. Purpose This study addresses the hypothesis that long-term oestrogen deficiency increases protein kinase A (PKA) and calcium/calmodulin-dependent kinase II (CaMKII) phosphorylation in cardiomyocytes, resulting in altered intracellular calcium regulation. Methods Female guinea pigs underwent sham (n = 7) or ovariectomy (OVx) (n = 8) operations and 150 days later, left ventricular myocytes were enzymatically isolated and loaded with fluo-4AM to monitor intracellular calcium. Calcium transients (CaT) were recorded using confocal microscopy. PKA and CaMKII phosphorylation were inhibited by superfusing cells with specific inhibitors, PKI and AIP, respectively. Experiments were carried out both in the presence and absence of β-agonist, isoprenaline (ISO), and relative changes to CaT parameters compared between OVx and sham cells. Results CaT amplitude was greater (p &lt; 0.05) in the OVx group (ΔF/Fo= 2.51 ± 0.57) compared with sham (ΔF/Fo = 2.16 ± 0.57). Inhibition of CaMKII phosphorylation increased CaT amplitude in the sham but not OVx group, both in the presence (by 22%, p &lt; 0.01) and absence of ISO (by 19%, p &lt; 0.01). Time to peak of the CaT increased to a greater extent following inhibition of PKA and CaMKII phosphorylation in the OVx group compared with sham, both in the presence (by 69%, p &lt; 0.0001) and absence (by 162%, p &lt; 0.0001) of ISO respectively. CaT decay time significantly increased (by 21%, p &lt; 0.01) in the sham group following inhibition of PKA and CaMKII together, whilst decay times in the OVx group remained unchanged in the presence and absence of ISO. At higher pacing rates, time to peak of the CaT decreased significantly (by 48%, p &lt; 0.01) in the OVx group but not sham with inhibition of phosphorylation. Conclusion Our findings suggest ovariectomy alters intracellular calcium regulation and some of these effects appear to be mediated by alterations in phosphorylation of calcium handling proteins and/or changes to sites of phosphorylation.

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