Abstract 13469: Drp1 Accumulates in Mitochondria and Plays a Protective Role in the Heart in Response to Pressure Overload

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Akihiro Shirakabe ◽  
Yoshiyuki Ikeda ◽  
Peiyong Zai ◽  
Junichi Sadoshima
Keyword(s):  
Diastolic Pressure ◽  
Pressure Overload ◽  
Protective Role ◽  
Left Ventricular ◽  
Multiple Time ◽  
Lung Weight ◽  
Knock Out ◽  
Multiple Time Points ◽  
Increased Activity ◽  
Adaptive Role

Dynamin-related protein 1 (Drp1) plays an essential role in maintaining the quality control of mitochondria through mitochondrial (Mt) fission and mitophagy. We investigated how Mt function, autophagy and Drp1 are regulated in the heart during pressure overload (PO) and whether endogenous Drp1 plays an important role in regulating cardiac function. Mice were subjected to transverse aortic constriction (TAC) at multiple time points between 6 hours and 30 days. Left ventricular (LV) weight/tibial length (LVW/TL) was significantly elevated at Day 7 (TAC vs sham; 5.92 ± 0.27 vs 4.22 ± 0.12, p<0.05). Ejection fraction (EF) was maintained at Day 7, but gradually decreased thereafter (at 30 days; 65±9 vs 83±9 %, p<0.05). LC3-II was decreased (-45.7%, p<0.05) while p62 accumulated (1.17 fold, p<0.05) significantly at Day 7. Both Mt ATP content (-65.6%, p<0.05) and production (-90.3%, p<0.05) were reduced significantly at Days 7 and 14, respectively, and thereafter. Mt mass, evaluated by electron microscopy, was also reduced (-19.9%, p<0.05) at Day 7. Drp1 accumulated in mitochondria at Day 7, and S616 phosphorylation of Drp1, associated with increased activity, was increased at Day 7. Thus, PO suppresses autophagy and induces Mt dysfunction by Day 7, at which time Drp1 accumulates in mitochondria and Mt mass is decreased. To examine the functional significance of endogenous Drp1 during PO, cardiac-specific heterozygous Drp1 knock out (Drp-hetCKO) mice were subjected to TAC. At Day 7, decreases in EF (61± 2 vs 84 ± 7%, p<0.05) and increases in LVW/TL (7.22 ± 0.26 vs 5.86 ± 0.65, p<0.05) and lung weight/TL (12.01 ± 1.10 vs 6.31 ± 1.19, p<0.05) were exacerbated in Drp-hetCKO compared to in control mice. LV end diastolic pressure was significantly higher (22.0 ± 2.8 vs 5.7 ± 2.9 mmHg, p<0.05) and myocardial fibrosis (14.1 ± 2.5 vs 6.2 ± 4.3 %, p<0.05) was greater in Drp-hetCKO than in control mice. Mt mass was also significantly greater in Drp-hetCKO than in control mice (relative Mt mass, 1.21 ± 0.46 vs 1.00 ± 0.02, p<0.05). These results suggest that PO inhibits autophagy and induces mitochondrial dysfunction by Day7, which coincides with Mt accumulation of Drp1. Drp1 plays an adaptive role in this condition, mediating decreases in Mt mass and protecting the heart from dysfunction.

Abstract 168: Drp1 Accumulates in Mitochondria and Plays a Protective Role in the Heart in Response to Pressure Overload

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Akihiro Shirakabe ◽  
Yoshiyuki Ikeda ◽  
Toshiro Saito ◽  
Peiyong Zhai ◽  
Junichi Sadoshima
Keyword(s):  
Diastolic Pressure ◽  
Pressure Overload ◽  
Protective Role ◽  
Left Ventricular ◽  
Multiple Time ◽  
Lung Weight ◽  
Knock Out ◽  
Multiple Time Points ◽  
Increased Activity ◽  
Adaptive Role

Dynamin-related protein 1 (Drp1) plays an essential role in maintaining the quality control of mitochondria through mitochondrial (Mt) fission and mitophagy. We investigated how Mt function, autophagy and Drp1 are regulated in the heart during pressure overload (PO) and whether endogenous Drp1 plays an important role in regulating cardiac function. Mice were subjected to transverse aortic constriction (TAC) at multiple time points between 6 hours and 30 days. Left ventricular (LV) weight/tibial length (LVW/TL) was significantly elevated at Day 5 (TAC vs Baseline; 6.21 ± 0.28 vs 4.59 ± 0.36, p<0.05). Ejection fraction (EF) was maintained at Day 5 (79±5 vs 82±7%), but gradually decreased thereafter (30 days; 51±12%, p<0.05). LC3-II was decreased (-40.0%, p<0.05) while p62 accumulated (1.84 fold, p<0.05) significantly at Day 5. Both Mt ATP content (-65.6%, p<0.05) and production (-90.3%, p<0.05) were reduced significantly at Days 7 and 14, respectively, and thereafter. Mt mass, evaluated by electron microscopy, was also reduced (-19.9%, p<0.05) at Day 7. Drp1 accumulated in mitochondria at Day 7, and S616 phosphorylation of Drp1, associated with increased activity, was increased at Day 7. Thus, PO suppresses autophagy and induces Mt dysfunction by Day 7, at which time Drp1 accumulates in mitochondria and Mt mass is decreased. To examine the functional significance of endogenous Drp1 during PO, cardiac-specific heterozygous Drp1 knock out (Drp-hetCKO) mice were subjected to TAC. At Day 7, decreases in EF (57± 11 vs 80 ± 7%, p<0.05) and increases in LVW/TL (7.22 ± 0.26 vs 5.86 ± 0.65, p<0.05) and lung weight/TL (13.03 ± 1.09 vs 7.00 ± 1.31, p<0.05) were exacerbated in Drp-hetCKO compared to in control mice. LV end diastolic pressure was significantly higher (20.0 ± 5.7 vs 7.4 ± 3.1 mmHg, p<0.05) and myocardial fibrosis (14.1 ± 2.5 vs 6.2 ± 4.3 %, p<0.05) was greater, and Mt mass was also significantly greater in Drp-hetCKO than in control mice (relative Mt mass, 1.21 ± 0.46 vs 1.00 ± 0.02, p<0.05). These results suggest that PO inhibits autophagy and induces mitochondrial dysfunction by Day7, which coincides with Mt accumulation of Drp1. Drp1 plays an adaptive role in this condition, mediating decreases in Mt mass and protecting the heart from dysfunction.

Abstract 83: Autophagy Protects the Heart Against Pressure Overload Induced Heart Failure

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Akihiro Shirakabe ◽  
Yoshiyuki Ikeda ◽  
Toshiro Saito ◽  
Peiyong Zhai ◽  
Junichi Sadoshima
Keyword(s):  
Heart Failure ◽  
Cardiac Dysfunction ◽  
Sham Group ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Autophagic Flux ◽  
Multiple Time ◽  
Double Positive ◽  
Lung Weight ◽  
Multiple Time Points

Autophagy is an important mechanism for the degradation of cytosolic proteins and organelles. We investigated how autophagy is regulated in the heart in response to pressure overload (PO). Mice were subjected to transverse aortic constriction (TAC) at multiple time points between 1 hours and 30 days. Left ventricular (LV) weight/tibial length (TL) was significantly elevated at Day 5 (6.21 ± 0.10 vs 4.59 ± 0.10, p<0.05) and thereafter. Ejection fraction (EF) was maintained at Day 7 (82.1±3.4 vs 78.4±3.2%), but gradually decreased thereafter (at Day 30; 51.0±4.5, p<0.05). The level of LC3II was rapidly increased and peaked at 3 hour (2.4 fold , p<0.05), returned to normal by 24 hours, and then significantly decreased at Day 5 (-40.0%, p<0.05) and thereafter. Autophagic flux was evaluated with tandem fluorescent LC3. At 6 hours, both GFP/RFP double positive (yellow) dots and RFP dots were significantly increased in the TAC group compared to the sham group with or without chloroquine (CQ) (yellow 12±2 vs 4±0 CQ(-), 23±3 vs 9±1 CQ(+); RFP 13±2 vs 5±1 CQ(-), 19±1 vs 13±1 CQ(+)). On the other hand, both yellow and RFP dots were significantly decreased at Day7 and thereafter in the TAC group compared to the sham group with or without CQ. These data suggest that autophagic flux is activated transiently after TAC, but is inactivated after Day 5. To examine the functional significance of autophagy during PO, beclin1 heterozygous KO ( beclin1 -hetKO) mice, atg7 cardiac specific KO (Atg7-CKO) mice, and cardiac-specific U6-shRNA beclin1 (U6shRNA beclin1 ) mice were subjected to TAC. At Day 7 or 14, decreases in EF (60.7 ± 4.8%, 53.8 ± 2.1% and 46.7 ± 5.9%, p<0.05) and increases in lung weight/TL (8.43 ± 0.87, 11.04 ± 4.16 and 18.76 ± 3.77, p<0.05) were exacerbated in beclin1 -hetKO, atg7 -CKO and U6shRNA beclin1 mice compared to in control mice. These results suggest that PO inhibits autophagy after Day5, which coincides with the development of cardiac dysfunction. Since heart failure is exacerbated by further suppression of autophagy, autophagy during PO protects the heart from cardiac dysfunction.

Abstract 867: The Longevity Factor Sirt1 Exacerbates LV Dysfunction and Energy Depletion in Response to Pressure Overload

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Ralph Alcendor ◽  
Chull Hong ◽  
Peiyong Zhai ◽  
Shumin Gao ◽  
Junichi Sadoshima
Keyword(s):  
Oxidative Stress ◽  
Stress Resistance ◽  
Diastolic Pressure ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Class Iii ◽  
Lung Weight ◽  
Energy Depletion ◽  
Lv Dysfunction ◽  
And Oxidative Stress

Sirt1, a class III histone deacetylase, extends the lifespan of many organisms. Longevity mechanisms usually confer stress resistance to organisms, and accumulation of stress resistance leads to lifespan extension. We have shown previously that Sirt1 is upregulated by stress up to 10 fold in the heart, and heart specific overexpression (up to 7.5 fold) of Sirt1 in mice not only suppresses histological/biochemical markers of aging, but also induces resistance to oxidative stress in the heart. We examined whether Sirt1 is protective against another pathologically relevant stimulus, namely pressure overload. Cardiac specific Sirt1 transgenic mice (Tg-Sirt1) from line #40, the line which has been shown to be protected against aging and oxidative stress, were subjected to transverse aortic constriction (TAC). Unexpectedly, at 10 days, the left ventricular (LV) ejection fraction (EF) in Tg-Sirt1 was significantly reduced (46 vs 71%, p<0.01), the LV end diastolic dimension was significantly increased (4.1 vs 3.4 mm, p<0.05), and the pressure gradient was reduced (92 vs 57 mmHg, p<0.05), possibly due to reduced LV contractility, in Tg-Sirt1 compared with non-transgenic (NTg) controls. At 4 weeks, LV weight/body weight (BW) (6.4 vs 4.7, p<0.05) and lung weight/BW (18.8 vs 7.0, p<0.05) were significantly increased in Tg-Sirt1, LV +dP/dt was significantly reduced (4617 vs 7513, p<0.05), and the LV end diastolic pressure was significantly elevated (13.6 vs 1.4 mmHg, p<0.05) in Tg-Sirt1 compared with NTg. These results suggest that Tg-Sirt1 mice develop more severe LV dysfunction than NTg in response to TAC. Tg-Sirt1 mice exhibited significantly less apoptosis (−50%, p<0.05) than NTg however, despite the development of LV dysfunction, suggesting that the LV dysfunction may be caused by apoptosis-independent mechanisms. The myocardial ATP content in Tg-Sirt1 was significantly less (−41%, p<0.05) than that in NTg after TAC. These results suggest that the cardioprotective effect of Sirt1 depends on the type of stress: although modest expression of Sirt1 confers resistance to aging and oxidative stress, it exacerbates heart failure in response to TAC through apoptosis-independent mechanisms possibly involving energy depletion.

Abstract 5394: H11 Kinase/Hsp22, A Novel Mechanism in the Transition to Heart Failure

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Hongyu Qiu ◽  
Chull Hong ◽  
Shumin Gao ◽  
Dorothy E Vatner ◽  
Stephen F Vatner ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Diastolic Pressure ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Lv Function ◽  
Area At Risk ◽  
Lung Weight ◽  
Tibial Length ◽  
Lv Ejection Fraction

H11 kinase/Hsp22 (H11K), a heat shock protein expressed mainly in the heart, is up-regulated upon pressure overload in animal models and in patients. Cardiac-specific over-expression of H11K in a transgenic model induces cardiac hypertrophy with normal function and cardioprotection against lethal ischemia. We tested the hypothesis that H11K deletion would accelerate the transition into heart failure (HF) following chronic pressure overload. An H11K knockout (KO) mouse was generated, which survives after birth with normal Mendelian distribution. In basal conditions (4/group), no differences were found between KO and wild type (WT) in terms of left ventricular (LV) mass (LV/tibial length: 4.6±0.3 vs 4.1±0.1, NS) or LV ejection fraction (69±3% vs 70±1%, NS). After two weeks aortic banding the KO mice, compared to WT, showed a slightly greater mass (LV/tibial length: 8.2±0.3 vs 7.0±0.4, P<0.05), impaired LV function (LV ejection fraction: 45±3% vs 62±5%, P<0.05), and signs of HF (lung weight/TL: 16.2±3 vs 7.7±0.4, P<0.05; LV end-diastolic pressure: 22±4 mmHg vs 7±4 mmHg, P<0.05). To test whether H11K participates in cardiac cell survival, both WT and KO mice were submitted to 30 min no-flow ischemia of the left anterior descending artery followed by 24 hours reperfusion and staining for the area-at-risk (AAR) and infarct size (IS). Whereas AAR was comparable between groups, the IS/AAR was more than doubled (P<0.01, n=3/group) in KO (61±2.8%) compared to WT (26±2.8%). Therefore, H11K deletion does not affect basal cardiac function but it precipitates the transition into HF following pressure overload, potentially by loss of H11K cardioprotective action. This research has received full or partial funding support from the American Heart Association, AHA National Center.

DNA enzyme targeting TNF-α mRNA improves hemodynamic performance in rats with postinfarction heart failure

2001 ◽  
Vol 281 (5) ◽  
pp. H2211-H2217 ◽  
Author(s):  
Per Ole Iversen ◽  
Gunnar Nicolaysen ◽  
Mouldy Sioud
Keyword(s):  
Heart Failure ◽  
Therapeutic Potential ◽  
Diastolic Pressure ◽  
Substantial Reduction ◽  
Left Ventricular ◽  
Lung Weight ◽  
Cleavage Activity ◽  
Arterial Blood ◽  
Modified Dna ◽  
Tnf Α

Tumor necrosis factor-α (TNF-α) probably affects the pathogenesis of heart failure. Here we have investigated the therapeutic potential of a nuclease-resistant DNA enzyme that specifically cleaves TNF-α mRNA. A phosphorothioate-modified DNA enzyme was designed to retain similar cleavage activity as its unmodified version, and that inhibited the expression of TNF-α in vitro. To test its efficacy in vivo, postinfarction congestive heart failure was induced in anesthetized rats by ligation of the left coronary artery. A 4-wk treatment with the DNA enzyme induced a substantial reduction in left ventricular end-diastolic pressure and lung weight concomitant with an increase in arterial blood pressure and myocardial blood flow compared with controls. The concentration of TNF-α in coronary sinus blood was markedly lowered on treatment, and myocardial TNF-α mRNA was substantially reduced. Recovery studies showed that the DNA enzyme cleavage activity was present within the myocardium throughout the observation period and had no apparent toxic effects. Our findings indicate that DNA enzyme-based therapy may hold promise in the treatment of this debilitating disease.

Abstract 370: Type 2 Diabetes Is Associated with the Exacerbation of Heart Failure via Increasing Myocardial NAD(P)H Oxidase-Derived Superoxide Production

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Shintaro Kinugawa ◽  
Shouji Matsushima ◽  
Takashi Yokota ◽  
Yukihiro Ohta ◽  
Naoki Inoue ◽  
...  
Keyword(s):  
Heart Failure ◽  
Type 2 Diabetes ◽  
Diastolic Pressure ◽  
Interstitial Fibrosis ◽  
Left Ventricular ◽  
Lung Weight ◽  
Tissue Mass ◽  
Tibial Length ◽  
Lv Remodeling

Type 2 diabetes mellitus (DM) adversely affects the outcomes in patients with myocardial infarction (MI), which is associated with the development of left ventricular (LV) remodeling and failure. NAD(P)H oxidase-derived superoxide (O 2 − ) production is increased in DM. However, its pathophysiological significance in advanced post-MI LV failure associated with DM remains unestablished. We thus determined whether an inhibitor of NAD(P)H oxidase activation, apocynin, could attenuate the exacerbated LV remodeling and heart failure after MI in high-fat diet (HFD)-induced obese mice with DM. Male C57BL/6J mice were fed on either HFD or normal diet (ND) for 8 weeks. At 4 weeks of feeding, MI was created in all mice by ligating left coronary artery. MI mice were treated with either apocynin (10 mmol/l in drinking water; n = 10 for ND and n = 11 for HFD) or vehicle (n = 15 for ND and n = 13 for HFD). HFD significantly increased body weight (BW), adipose tissue mass, fasting plasma glucose and insulin levels compared to ND after 4 and 8 weeks. HFD + MI had significantly greater LV end-diastolic diameter (LVEDD; 5.7 ± 0.1 vs. 5.3 ± 0.2 mm) by echocardiography, end-diastolic pressure (EDP; 12 ± 2 vs. 8 ± 1 mmHg) and lung weight/tibial length (10.1 ± 0.3 vs. 8.7 ± 0.7 mg/mm) than ND + MI, which was accompanied by an increased interstitial fibrosis of non-infarcted LV. Treatment of HFD + MI with apocynin significantly decreased LVEDD (5.4 ± 0.1 mm), LVEDP (9.7 ± 0.8 mmHg), lung weight/tibial length (9.0 ± 0.3 mg/mm), and concomitantly interstitial fibrosis of non-infarcted LV to ND + MI level without affecting BW, glucose metabolism, infarct size and aortic pressure. On the other hand, treatment of ND + MI with apocynin did not affect LV remodeling and failure. NAD(P)H oxidase activity, O 2 − production measured by lucigenin chemiluminescence, and thiobarbituric acid-reactive substances were increased in non-infarcted LV tissues from HFD + MI, all of which were also attenuated by apocynin to ND + MI level. Type 2 DM was associated with the exacerbation of LV remodeling and failure after MI via increasing NAD(P)H oxidase derived O 2 − production, which may be a novel important therapeutic target in advanced heart failure with DM.

Apoptosis in the left ventricle of chronic volume overload causes endocardial endothelial dysfunction in rats

2002 ◽  
Vol 282 (4) ◽  
pp. H1197-H1205 ◽  
Author(s):  
Michael J. Cox ◽  
Harpreet S. Sood ◽  
Matthew J. Hunt ◽  
Derrick Chandler ◽  
Jeffrey R. Henegar ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Blot Analysis ◽  
Diastolic Pressure ◽  
Volume Overload ◽  
Left Ventricular ◽  
Tissue Inhibitor Of Metalloproteinase ◽  
Heart Weight ◽  
Sprague Dawley ◽  
Lung Weight ◽  
Cardiac Relaxation

The hypothesis is that chronic increases in left ventricular (LV) load induce oxidative stress and latent matrix metalloproteinase (MMP) is activated, allowing the heart to dilate in the absence of endothelial nitric oxide (NO) and thereby reduce filling pressure. To create volume overload, an arteriovenous (A-V) fistula was placed in male Sprague-Dawley rats. To decrease oxidative stress and apoptosis, 0.08 mg/ml nicotinamide (Nic) was administered in drinking water 2 days before surgery. The rats were divided into the following groups: 1) A-V fistula, 2) A-V fistula + Nic, 3) sham operated, 4) sham + Nic, and 5) control (unoperated); n = 6 rats/group. After 4 wk, hemodynamic parameters were measured in anesthetized rats. The heart was removed and weighed, and LV tissue homogeneates were prepared. A-V fistula caused an increase in heart weight, lung weight, and end-diastolic pressure compared with the sham group. The levels of malondialdehyde (MDA; a marker of oxidative stress) was 6.60 ± 0.23 ng/mg protein and NO was 6.87 ± 1.21 nmol/l in the LV of A-V fistula rats by spectrophometry. Nic treatment increased NO to 13.88 ± 2.5 nmol/l and decreased MDA to 3.54 ± 0.34 ng/mg protein ( P= 0.005). Zymographic levels of MMP-2 were increased, as were protein levels of nitrotyrosine and collagen fragments by Western blot analysis. The inhibition of oxidative stress by Nic decreased nitrotyrosine content and MMP activity. The levels of tissue inhibitor of metalloproteinase-4 mRNA were decreased in A-V fistula rats and increased in A-V fistula rats treated with Nic by Northern blot analysis. TdT-mediated dUTP nick-end labeling-positive cells were increased in A-V fistula rats and decreased in fistula rats treated with Nic. Acetylcholine and nitroprusside responses in cardiac rings prepared from the above groups of rats suggest impaired endothelial-dependent cardiac relaxation. Treatment with Nic improves cardiac relaxation. The results suggest that an increase in the oxidative stress and generation of nitrotyrosine are, in part, responsible for the activation of metalloproteinase and decreased endocardial endothelial function in chronic LV volume overload.

Heart functional responses to pressure overload in exercised and sedentary rats

1976 ◽  
Vol 230 (1) ◽  
pp. 199-204 ◽  
Author(s):  
RT Dowell ◽  
AF Cutilletta ◽  
MA Rudnik ◽  
PC Sodt
Keyword(s):  
Cardiac Output ◽  
Diastolic Pressure ◽  
Heart Function ◽  
Pressure Overload ◽  
Normal Growth ◽  
Left Ventricular ◽  
Treadmill Running ◽  
Female Rats ◽  
Heart Weight ◽  
Functional Responses

Female rats that had been subjected to a moderate treadmill running program were compared with sedentary animals on the basis of heart weight, selected biochemical measurements, and heart function. Exercised animals maintained normal growth rate, and cardiac hypertrophy was not present. Left ventricular RNA, DNA, and cytochrome c levels were unchanged. Heart functional measurements obtained in situ were similar in sedentary and exercised animals under control conditions. When subjected to sustained (1-3 days) aortic constriction pressure overload, exercised animals maintained or increased myocardial contractility. Contractility was depressed in sedentary animals. Both sedentary and exercised animals increased left ventricular end diastolic pressure without changing contractility during acute (1-3 min) pressure overload. However, exercised animals were able to fully regain normal cardiac output when the acute overload was relieved. Cardiac output remained approximately 10% below control in sedentary animals. The improved ability of previously exercised animals to withstand pressure overload appears to be due to alterations in adaptation rather than preliminary augmentation of metabolism or function.

Colchicine attenuates left ventricular hypertrophy but preserves cardiac function of aortic-constricted rats

2003 ◽  
Vol 94 (4) ◽  
pp. 1627-1633 ◽  
Author(s):  
Beatriz S. Scopacasa ◽  
Vicente P. A. Teixeira ◽  
Kleber G. Franchini
Keyword(s):  
Diastolic Pressure ◽  
Systolic Pressure ◽  
Pressure Overload ◽  
Colchicine Treatment ◽  
Average Diameter ◽  
Left Ventricular ◽  
Lv Function ◽  
Right Ventricular Mass ◽  
Lv Mass ◽  
Phenylephrine Infusion

To investigate the effects of colchicine on left ventricular (LV) function and hypertrophy (LVH) of rats subjected to constriction of transverse aorta (TAoC), we evaluated SO (sham operated, vehicle; n = 25), SO-T (sham operated, colchicine 0.4 mg/kg body wt ip daily; n = 38), TAoC (vehicle; n = 37), and TAoC-T (TAoC, colchicine; n = 34) on the 2nd, 6th, and 15th day after surgery. Colchicine attenuated LVH of TAoC-T compared with TAoC rats, as evaluated by ratio between LV mass (LVM) and right ventricular mass, LV wall thickness, and average diameter of cardiac myocytes. Systolic gradient across TAoC (∼45 mmHg), LV systolic pressure, LV end-diastolic pressure, and rate of LV pressure increase (+dP/d t) were comparable in TAoC-T and TAoC rats. However, the baseline and increases of LV systolic pressure-to-LVM and +dP/d t-to-LVMratios induced by phenylephrine infusion were greater in TAoC-T and SO-T compared with SO rats. Baseline and increases of +dP/d t-to-LVM ratio were reduced in TAoC compared with SO rats. TAoC rats increased polymerized fraction of tubulin compared with SO, SO-T, and TAoC-T rats. Our results indicate that colchicine treatment reduced LVH to pressure overload but preserved LV function.

Diverse regulation of IP3 and ryanodine receptors by pentazocine through σ1-receptor in cardiomyocytes

2013 ◽  
Vol 305 (8) ◽  
pp. H1201-H1212 ◽  
Author(s):  
Hideaki Tagashira ◽  
Md. Shenuarin Bhuiyan ◽  
Kohji Fukunaga
Keyword(s):  
Cardiac Hypertrophy ◽  
Diastolic Pressure ◽  
Ryanodine Receptors ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Female Rats ◽  
In Vivo Studies ◽  
Atp Production ◽  
Cultured Cardiomyocytes

Although pentazocine binds to σ1-receptor (σ1R) with high affinity, the physiological relevance of its binding remains unclear. We first confirmed that σ1R stimulation with pentazocine rescues contractile dysfunction following pressure overload (PO)-induced cardiac hypertrophy ovariectomized (OVX) female rats. In in vivo studies, vehicle, pentazocine (0.5–1.0 mg/kg ip), and NE-100 (1.0 mg/kg po), a σ1R antagonist, were administered for 4 wk (once daily) starting from the onset of aortic banding after OVX. We also examined antihypertrophic effects of pentazocine (0.5–1 μM) in cultured cardiomyocytes exposed to angiotensin II. Pentazocine administration significantly inhibited PO-induced cardiac hypertrophy and rescued hypertrophy-induced impairment of cardiac dysfunctions such as left ventricular end-diastolic pressure, left ventricular developed pressure, and left ventricular contraction and relaxation (±dp/dt) rates. Coadministration of NE-100 with pentazocine eliminated pentazocine-induced amelioration of heart dysfunction. Interestingly, pentazocine administration inhibited PO-induced σ1R reduction and inositol-1,4,5-trisphosphate (IP3) receptor type 2 (IP3R2) upregulation in heart. Therefore, the reduced mitochondrial ATP production following PO was restored by pentazocine administration. Furthermore, we found that σ1R binds to the ryanodine receptor (RyR) in addition to IP3 receptor (IP3R) in cardiomyocytes. The σ1R/RyR complexes were decreased following OVX-PO and restored by pentazocine administration. We noticed that pentazocine inhibits the ryanodine-induced Ca2+ release from sarcoplasmic reticulum (SR) in cultured cardiomyocytes. Taken together, the stimulation of σ1R by pentazocine rescues cardiac dysfunction by restoring IP3R-mediated mitochondrial ATP production and by suppressing RyR-mediated Ca2+ leak from SR in cardiomyocytes.

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