scholarly journals BH4 Increases nNOS Activity and Preserves Left Ventricular Function in Diabetes

Author(s):  
Ricardo Carnicer Hijazo ◽  
Drew Duglan ◽  
Klemen Ziberna ◽  
Alice Recalde ◽  
Svetlana Reilly ◽  
...  

Rationale: In diabetic patients, heart failure with predominant left ventricular (LV) diastolic dysfunction is a common complication for which there is no effective treatment. Oxidation of the nitric oxide synthase (NOS) co-factor tetrahydrobiopterin (BH4) and dysfunctional NOS activity have been implicated in the pathogenesis of the diabetic vascular and cardiomyopathic phenotype. Objective: Using mice models and human myocardial samples, we evaluated whether and by which mechanism increasing myocardial BH4 availability prevented or reversed LV dysfunction induced by diabetes. Methods and Results: In contrast to the vascular endothelium, BH4 levels, superoxide production and NOS activity (by liquid chromatography) did not differ in the LV myocardium of diabetic mice or in atrial tissue from diabetic patients. Nevertheless, the impairment in both cardiomyocyte relaxation and [Ca2+]i decay and in vivo LV function (echocardiography and tissue Doppler) that developed in wild type mice (WT) 12 weeks post-DM induction (streptozotocin, 42-45mg/kg) was prevented in mice with elevated myocardial BH4 content secondary to overexpression of GTP-cyclohydrolase 1 (mGCH1-Tg) and reversed in WT mice receiving oral BH4 supplementation from the 12th to the 18th week after DM induction. The protective effect of BH4 was abolished by CRISPR/Cas9-mediated knockout of neuronal NOS (nNOS) in mGCH1-Tg. In HEK cells, S-nitrosoglutathione led to a PKG-dependent increase in plasmalemmal density of the insulin-independent glucose transporter, GLUT-1. In cardiomyocytes, mGCH1 overexpression induced a NO/sGC/PKG-dependent increase in glucose uptake via GLUT-1, which was instrumental in preserving mitochondrial creatine kinase activity, oxygen consumption rate, LV energetics (by 31P MRS) and myocardial function. Conclusions: We uncovered a novel mechanism whereby myocardial BH4 prevents and reverses LV diastolic and systolic dysfunction associated with diabetes via a nNOS-mediated increase in non-insulin dependent myocardial glucose uptake and utilization. These findings highlight the potential of GCH1/BH4-based therapeutics in human diabetic cardiomyopathy.

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 552 ◽  
Author(s):  
Hanna Sarah Kutsche ◽  
Rolf Schreckenberg ◽  
Martin Weber ◽  
Christine Hirschhäuser ◽  
Susanne Rohrbach ◽  
...  

The cardiac expression of the mitochondrial uncoupling protein (UCP)-2 is increased in patients with heart failure. However, the underlying causes as well as the possible consequences of these alterations during the transition from hypertrophy to heart failure are still unclear. To investigate the role of UCP-2 mechanistically, expression of UCP-2 was silenced by small interfering RNA in adult rat ventricular cardiomyocytes. We demonstrate that a downregulation of UCP-2 by siRNA in cardiomyocytes preserves contractile function in the presence of angiotensin II. Furthermore, silencing of UCP-2 was associated with an upregulation of glucose transporter type (Glut)-4, increased glucose uptake, and reduced intracellular lactate levels, indicating improvement of the oxidative glucose metabolism. To study this adaptation in vivo, spontaneously hypertensive rats served as a model for cardiac hypertrophy due to pressure overload. During compensatory hypertrophy, we found low UCP-2 levels with an upregulation of Glut-4, while the decompensatory state with impaired function was associated with an increase of UCP-2 and reduced Glut-4 expression. By blocking the aldosterone receptor with spironolactone, both cardiac function as well as UCP-2 and Glut-4 expression levels of the compensated phase could be preserved. Furthermore, we were able to confirm this by left ventricular (LV) biopsies of patients with end-stage heart failure. The results of this study show that UCP-2 seems to impact the cardiac glucose metabolism during the transition from hypertrophy to failure by affecting glucose uptake through Glut-4. We suggest that the failing heart could benefit from low UCP-2 levels by improving the efficiency of glucose oxidation. For this reason, UCP-2 inhibition might be a promising therapeutic strategy to prevent the development of heart failure.


2005 ◽  
Vol 289 (6) ◽  
pp. H2401-H2408 ◽  
Author(s):  
Lazaros A. Nikolaidis ◽  
Dariush Elahi ◽  
You-Tang Shen ◽  
Richard P. Shannon

We have shown previously that the glucagon-like peptide-1 (GLP-1)-(7–36) amide increases myocardial glucose uptake and improves left ventricular (LV) and systemic hemodynamics in both conscious dogs with pacing-induced dilated cardiomyopathy (DCM) and humans with LV systolic dysfunction after acute myocardial infarction. However, GLP-1-(7–36) is rapidly degraded in the plasma to GLP-1-(9–36) by dipeptidyl peptidase IV (DPP IV), raising the issue of which peptide is the active moiety. By way of methodology, we compared the efficacy of a 48-h continuous intravenous infusion of GLP-1-(7–36) (1.5 pmol·kg−1·min−1) to GLP-1-(9–36) (1.5 pmol·kg−1·min−1) in 28 conscious, chronically instrumented dogs with pacing-induced DCM by measuring LV function and transmyocardial substrate uptake under basal and insulin-stimulated conditions using hyperinsulinemic-euglycemic clamps. As a result, dogs with DCM demonstrated myocardial insulin resistance under basal and insulin-stimulated conditions. Both GLP-1-(7–36) and GLP-1-(9–36) significantly reduced ( P < 0.01) LV end-diastolic pressure [GLP-1-(7–36), 28 ± 1 to 15 ± 2 mmHg; GLP-1-(9–36), 29 ± 2 to 16 ± 1 mmHg] and significantly increased ( P < 0.01) the first derivative of LV pressure [GLP-1-(7–36), 1,315 ± 81 to 2,195 ± 102 mmHg/s; GLP-1-(9–36), 1,336 ± 77 to 2,208 ± 68 mmHg] and cardiac output [GLP-1-(7–36), 1.5 ± 0.1 to 1.9 ± 0.1 l/min; GLP-1-(9–36), 2.0 ± 0.1 to 2.4 ± 0.05 l/min], whereas an equivolume infusion of saline had no effect. Both peptides increased myocardial glucose uptake but without a significant increase in plasma insulin. During the GLP-1-(9–36) infusion, negligible active (NH2-terminal) peptide was measured in the plasma. In conclusion, in DCM, GLP-1-(9–36) mimics the effects of GLP-1-(7–36) in stimulating myocardial glucose uptake and improving LV and systemic hemodynamics through insulinomimetic as opposed to insulinotropic effects. These data suggest that GLP-1-(9–36) amide is an active peptide.


2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Carlo G Tocchetti ◽  
Carmela Coppola ◽  
Domenica Rea ◽  
Antonio Barbieri ◽  
Giuseppe Palma ◽  
...  

Background: ErbB2, tyrosine kinase receptor of the EGFR family, overexpressed in about 25% of breast cancers, modulates development and function in the myocardium. Lapatinib (LAP) is a small molecule that inhibits ErbB2-tyrosine kinase domain. The few existing trials report it to be associated with a low risk of LV dysfunction (2%), while the prototypical antibody Trastuzumab (TRAS) increases the frequency of asymptomatic ejection fraction decrease by 3-18%, and the risk of heart failure by 2-4%. Here, we characterize our LAP murine cardiotoxicity model in vivo by echocardiography, comparing it to TRAS and doxorubicin (DOX) cardiotoxicities. Methods: LV end-diastolic and end-systolic diameters (LVEDD and LVESD) were assessed. LV function was measured with fractional shortening (FS) by M-mode echo, and with radial myocardial strain (%) with speckle tracking (ST) in sedated C57BL6 mice (2-4 mo. old) at day 0, and after 2 and 7 days of daily administration of LAP (100mg/kg/day orally), and in control mice. For comparison we used our well-established models with TRAS (2.25 mg/kg/day, ip), and DOX (2.17 mg/kg/day ip) as positive control. Results: FS was already reduced with DOX at 2 days: 52±.2%, p<.001 vs 60±.4% (sham), while LAP and TRAS decreased FS only at 7 days (56±2 and 49±1.5%, respectively, both p<.05 vs 60±.5% for sham). Interestingly, FS reduction with LAP was milder than with TRAS (p=.01). At 7 days, both LAP and TRAS only increased LVESD: 1.23±.07 and 1.49±.07mm, respectively, both p<.05 vs 1.1±.03mm (sham). On the other hand, at 7 days DOX induced LV dilation, with significant enlargement of both LVESD (1.55±.08mm) and LVEDD (3.04±.06mm; sham=2.81±.03mm), both p<.005. Importantly, from a diagnostic point of view, myocardial strain was reduced early at 2 days with LAP and TRAS, predicting cardiotoxicity: 34±7% for LAP, 44±7% for TRAS, both p<.05 vs sham (66±.6%). Conclusions: Differently from DOX, ErbB2 inhibition in mice does not produce LV dilation, but only decreases LV function. In particular, specifically targeting ErbB2-tyrosine kinase domain with LAP confers less cardiotoxicity than TRAS. Myocardial strain identifies LV systolic dysfunction earlier than conventional echo and can be a useful tool to predict ErbB2 inhibitors cardiotoxicity.


Author(s):  
Jie Li ◽  
Brandon A. Kemp ◽  
Nancy L. Howell ◽  
James Massey ◽  
Krzysztof Mińczuk ◽  
...  

Background Sustained pressure overload leads to changes in cardiac metabolism, function, and structure. Both time course and causal relationships between these changes are not fully understood. Therefore, we studied spontaneously hypertensive rats (SHR) during early hypertension development and compared them to control Wistar Kyoto rats. Methods and Results We serially evaluated myocardial glucose uptake rates (Ki) with dynamic 2‐[ 18 F] fluoro‐2‐deoxy‐D‐glucose positron emission tomography, and ejection fraction and left ventricular mass to body weight ratios with cardiac magnetic resonance imaging in vivo, determined glucose uptake and oxidation rates in isolated perfused hearts, and analyzed metabolites, mammalian target of rapamycin activity and endoplasmic reticulum stress in dissected hearts. When compared with Wistar Kyoto rats, SHR demonstrated increased glucose uptake rates (Ki) in vivo, and reduced ejection fraction as early as 2 months of age when hypertension was established. Isolated perfused SHR hearts showed increased glucose uptake and oxidation rates starting at 1 month. Cardiac metabolite analysis at 2 months of age revealed elevated pyruvate, fatty acyl‐ and branched chain amino acid‐derived carnitines, oxidative stress, and inflammation. Mammalian target of rapamycin activity increased in SHR beginning at 2 months. Left ventricular mass to body weight ratios and endoplasmic reticulum stress were elevated in 5 month‐old SHR. Conclusions Thus, in a genetic hypertension model, chronic cardiac pressure overload promptly leads to increased myocardial glucose uptake and oxidation, and to metabolite abnormalities. These coincide with, or precede, cardiac dysfunction while left ventricular hypertrophy develops only later. Myocardial metabolic changes may thus serve as early diagnostic markers for hypertension‐induced left ventricular hypertrophy.


2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Fabio Chirillo ◽  
Anna Baritussio ◽  
Umberto Cucchini ◽  
Ermanno Toniolli ◽  
Angela Polo ◽  
...  

Abstract Background Peripartum cardiomyopathy (PPCM) is usually characterized by overt heart failure, but other clinical scenarios are possible, sometimes making the diagnosis challenging. Case summary We report a case series of four patients with PPCM. The first patient presented with acute heart failure due to left ventricular (LV) systolic dysfunction. Following medical treatment, LV function recovered completely at 1 month. The second patient had systemic and pulmonary thromboembolism, secondary to severe biventricular dysfunction with biventricular thrombi. The third patient presented with myocardial infarction with non-obstructed coronary arteries and evidence of an aneurysm of the mid-anterolateral LV wall. The fourth patient, diagnosed with PPCM 11 years earlier, presented with sustained ventricular tachycardia. A repeat cardiac magnetic resonance, compared to the previous one performed 11 years earlier, showed an enlarged LV aneurysm in the mid-LV anterolateral wall with worsened global LV function. Discussion Peripartum cardiomyopathy may have different clinical presentations. Attentive clinical evaluation and multimodality imaging can provide precise diagnostic and prognostic information.


2012 ◽  
Vol 24 (2) ◽  
pp. 344 ◽  
Author(s):  
M. Garcia-Herreros ◽  
I. M. Aparicio ◽  
D. Rath ◽  
T. Fair ◽  
P. Lonergan

Previous studies have shown that developmental kinetic rates following IVF are lower in female than in male blastocysts and that this may be related to differences in glucose metabolism. In addition, an inhibition of phosphatidylinositol 3-kinase (PI3-K) inhibits glucose uptake in murine blastocysts. Therefore, the aim of this study was to identify and compare the expression of proteins involved in glucose metabolism (hexokinase-I, HK-I; phosphofructokinase-1, PFK-1; pyruvate kinase1/2, PK1/2; glyceraldehyde-3-phosphate dehydrogenase, GAPDH; glucose transporter-1, GLUT-1; and glycogen synthase kinase-3, GSK-3) in male and female bovine blastocysts to determine whether PI3-K has a role in the regulation of the expression of these proteins. Hexokinase-I, PFK-1, PK1/2, GAPDH and GLUT-1 were present in bovine embryos. Protein expression of these proteins and GSK-3 was significantly higher in male compared with female blastocysts. Inhibition of PI3-K with LY294002 significantly decreased the expression of HK-I, PFK-1, GAPDH, GSK-3 A/B and GLUT-1. Results showed that the expression of glycolytic proteins HK-I, PFK-1, GAPDH and PK1/2, and the transporters GLUT-1 and GSK-3 is regulated by PI3-K in bovine blastocysts. Moreover, the differential protein expression observed between male and female blastocysts might explain the faster developmental kinetics seen in males, as the expression of main proteins involved in glycolysis and glycogenogenesis was significantly higher in male than female bovine embryos and also could explain the sensitivity of male embryos to a high concentration of glucose, as a positive correlation between GLUT-1 expression and glucose uptake in embryos has been demonstrated.


2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Hua Wang ◽  
Xiaoyan Zhang ◽  
Shauna M. Dorsey ◽  
Jeremy R. McGarvey ◽  
Kenneth S. Campbell ◽  
...  

Myocardial contractility of the left ventricle (LV) plays an essential role in maintaining normal pump function. A recent ex vivo experimental study showed that cardiomyocyte force generation varies across the three myocardial layers of the LV wall. However, the in vivo distribution of myocardial contractile force is still unclear. The current study was designed to investigate the in vivo transmural distribution of myocardial contractility using a noninvasive computational approach. For this purpose, four cases with different transmural distributions of maximum isometric tension (Tmax) and/or reference sarcomere length (lR) were tested with animal-specific finite element (FE) models, in combination with magnetic resonance imaging (MRI), pressure catheterization, and numerical optimization. Results of the current study showed that the best fit with in vivo MRI-derived deformation was obtained when Tmax assumed different values in the subendocardium, midmyocardium, and subepicardium with transmurally varying lR. These results are consistent with recent ex vivo experimental studies, which showed that the midmyocardium produces more contractile force than the other transmural layers. The systolic strain calculated from the best-fit FE model was in good agreement with MRI data. Therefore, the proposed noninvasive approach has the capability to predict the transmural distribution of myocardial contractility. Moreover, FE models with a nonuniform distribution of myocardial contractility could provide a better representation of LV function and be used to investigate the effects of transmural changes due to heart disease.


Author(s):  
Hye Kyoung Sung ◽  
Patricia L. Mitchell ◽  
Sean Gross ◽  
Andre Marette ◽  
Gary Sweeney

Adiponectin is well established to mediate many beneficial metabolic effects, and this has stimulated great interest in development and validation of adiponectin receptor agonists as pharmaceutical tools. This study investigated the effects of ALY688, a peptide-based adiponectin receptor agonist, in rat L6 skeletal muscle cells. ALY688 significantly increased phosphorylation of several adiponectin downstream effectors, including AMPK, ACC and p38MAPK, assessed by immunoblotting and immunofluorescence microscopy. Temporal analysis using cells expressing an Akt biosensor demonstrated that ALY688 enhanced insulin sensitivity. This effect was associated with increased insulin-stimulated Akt and IRS-1 phosphorylation. The functional metabolic significance of these signaling effects was examined by measuring glucose uptake in myoblasts stably overexpressing the glucose transporter GLUT4. ALY688 treatment both increased glucose uptake itself and enhanced insulin-stimulated glucose uptake. In the model of high glucose/high insulin (HGHI)-induced insulin resistant cells, both temporal studies using the Akt biosensor as well as immunoblotting assessing Akt and IRS-1 phosphorylation indicated that ALY688 significantly reduced insulin resistance. Importantly, we observed that ALY688 administration to high-fat high sucrose fed mice also improve glucose handling, validating its efficacy in vivo. In summary, these data indicate that ALY688 activates adiponectin signaling pathways in skeletal muscle, leading to improved insulin sensitivity and beneficial metabolic effects.


1998 ◽  
Vol 274 (3) ◽  
pp. H937-H944 ◽  
Author(s):  
M. Miyamoto ◽  
D. E. McClure ◽  
E. R. Schertel ◽  
P. J. Andrews ◽  
G. A. Jones ◽  
...  

In previous studies, we observed left ventricular (LV) systolic and diastolic dysfunction in association with interstitial myocardial edema (IME) induced by either coronary venous hypertension (CVH) or lymphatic obstruction. In the present study, we examined the effects of myocardial edema induced by acute hypoproteinemia (HP) on LV systolic and diastolic function. We also combined the methods of HP and CVH (HP-CVH) to determine their combined effects on LV function and myocardial water content (MWC). We used a cell-saving device to lower plasma protein concentration in HP and HP-CVH groups. CVH was induced by inflating the balloon in the coronary sinus. Six control dogs were treated to sham HP. Conductance and micromanometer catheters were used to assess LV function. Contractility, as measured by preload recruitable stroke work, did not change in control or HP groups but declined significantly (14.5%) in the HP-CVH group. The time constant of isovolumic LV pressure decline (τ) increased significantly from baseline by 3 h in the HP (24.8%) and HP-CVH (27.1%) groups. The end-diastolic pressure-volume relationship (stiffness) also increased significantly from baseline by 3 h in the HP (78.6%) and HP-CVH (42.6%) groups. Total plasma protein concentration decreased from 5.2 ± 0.2 g/dl at baseline to 2.5 ± 0.0 g/dl by 3 h in the HP and HP-CVH groups. MWC of the HP (79.8 ± 0.25%) and HP-CVH groups (79.8 ±0.2%) were significantly greater than that of the control group (77.8 ± 0.3%) but not different from one another. In conclusion, hypoproteinemia-induced myocardial edema was associated with diastolic LV dysfunction but not systolic dysfunction. The edema caused by hypoproteinemia was more than twice that produced by our previous models, yet it was not associated with systolic dysfunction. CVH had a negative inotropic effect and no significant influence on MWC. IME may not have the inverse causal relationship with LV contractility that has been previously postulated but appears to have a direct causal association with diastolic stiffness as has been previously demonstrated.


2011 ◽  
Vol 51 (2) ◽  
pp. 79
Author(s):  
Erlina Masniari Napitupulu ◽  
Fera Wahyuni ◽  
Tina Christina L. Tobing ◽  
Muhammad Ali ◽  
Bidasari Lubis

Background Chronic severe anemia is a connnon disease. Cardiac output may increase when the hemoglobin (Hb) level decreases to < 7 g/dL for 3 months or more. Alteration of left ventricular (LV) function occurs frequently in children 'With chronic severe anemia, in the {onn of concentric LV hypertrophy, LV dilatation with or v.ithout LV hypertrophy, or systolic dysfunction. Objective To examine the correlation between Hb level and alteration of LV systolic function in children with chronic severe anemia. Methods We conducted a cross-sectional study in Adam Malik Hospital from October to December 2009. Subjects were chronic severely anemic children. Left ventricular systolic function (ejection fraction/EF, fractional shortening/FS) and dimensions (left ventricular end diastolic diameter/LVEDD and left ventricular end systolic diameter/LVESD) were measured using Hitachi EUB 5500 echocardiography unit. Univariate analysis  and Pearson correlation were performed.Results Thirty children were enrolled in the study. The mean of age was 113.5 months (SD 53.24). Hb values ranged from 2.1 to 6.9 g/dL with mean value of 4.6 g/dL (SD 1.44). Mean duration of anemia was 3.9 months (SD 0.70). Chronic severe anemia was not associated \\lith decreased LV systolic function [EF 62.2% (SD 9.16), r =0.296, P=0.112; FS 33.8% (SD 7.26), r =0.115, P=0.545], nor LV dimension changes [LVEDD 40.2 mm (SD 6.85), r = -0.192, P=0.308; LVESD 26.2 mm (SD 4.98), r=-0.266, P=0.156]. Conclusion There was no correlation between Hb level in chronically anemic children and changes in LV systolic function or dimension.


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