Cardiac Mast Cells Mediate Left Ventricular Fibrosis in the Hypertensive Rat Heart

AbstractCardiac magnetic resonance (CMR) is emerging as an important tool in the assessment of heart failure with preserved ejection fraction (HFpEF). This study sought to investigate the prognostic value of multiparametric CMR, including left and right heart volumetric assessment, native T1-mapping and LGE in HFpEF. In this retrospective study, we identified patients with HFpEF who have undergone CMR. CMR protocol included: cines, native T1-mapping and late gadolinium enhancement (LGE). The mean follow-up period was 3.2 ± 2.4 years. We identified 86 patients with HFpEF who had CMR. Of the 86 patients (85% hypertensive; 61% males; 14% cardiac amyloidosis), 27 (31%) patients died during the follow up period. From all the CMR metrics, LV mass (area under curve [AUC] 0.66, SE 0.07, 95% CI 0.54–0.76, p = 0.02), LGE fibrosis (AUC 0.59, SE 0.15, 95% CI 0.41–0.75, p = 0.03) and native T1-values (AUC 0.76, SE 0.09, 95% CI 0.58–0.88, p < 0.01) were the strongest predictors of all-cause mortality. The optimum thresholds for these were: LV mass > 133.24 g (hazard ratio [HR] 1.58, 95% CI 1.1–2.2, p < 0.01); LGE-fibrosis > 34.86% (HR 1.77, 95% CI 1.1–2.8, p = 0.01) and native T1 > 1056.42 ms (HR 2.36, 95% CI 0.9–6.4, p = 0.07). In multivariate cox regression, CMR score model comprising these three variables independently predicted mortality in HFpEF when compared to NTproBNP (HR 4 vs HR 1.65). In non-amyloid HFpEF cases, only native T1 > 1056.42 ms demonstrated higher mortality (AUC 0.833, p < 0.01). In patients with HFpEF, multiparametric CMR aids prognostication. Our results show that left ventricular fibrosis and hypertrophy quantified by CMR are associated with all-cause mortality in patients with HFpEF.

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Dobutamine responsiveness, PET mismatch, and lack of necrosis in low-flow ischemia: is this hibernation in the isolated rat heart?

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00906.2002 ◽

2003 ◽

Vol 285 (1) ◽

pp. H316-H324 ◽

Cited By ~ 10

Author(s):

Richard Southworth ◽

Pamela B. Garlick

Keyword(s):

Rat Heart ◽

Recovery Of Function ◽

Electron Microscopic Examination ◽

Left Ventricular ◽

Isolated Rat Heart ◽

Low Flow ◽

Hibernating Myocardium ◽

Heart Model ◽

Electron Microscopic ◽

Isolated Rat

The clinical hallmarks of hibernating myocardium include hypocontractility while retaining an inotropic reserve (using dobutamine echocardiography), having normal or increased [18F]fluoro-2-deoxyglucose-6-phosphate (18FDG6P) accumulation associated with decreased coronary flow [flow-metabolism mismatch by positron emission tomography (PET)], and recovering completely postrevascularization. In this study, we investigated an isolated rat heart model of hibernation using experimental equivalents of these clinical techniques. Rat hearts ( n = 5 hearts/group) were perfused with Krebs-Henseleit buffer for 40 min at 100% flow and 3 h at 10% flow and reperfused at 100% flow for 30 min (paced at 300 beats/min throughout). Left ventricular developed pressure fell to 30 ± 8% during 10% flow and recovered to 90 ± 7% after reperfusion. In an additional group, this recovery of function was found to be preserved over 2 h of reperfusion. Electron microscopic examination of hearts fixed at the end of the hibernation period demonstrated a lack of ischemic injury and an accumulation of glycogen granules, a phenomenon observed clinically. In a further group, hearts were challenged with dobutamine during the low-flow period. Hearts demonstrated an inotropic reserve at the expense of increased lactate leakage, with no appreciable creatine kinase release. PET studies used the same basic protocol in both dual- and globally perfused hearts (with 250MBq18FDG in Krebs buffer ± 0.4 mmol/l oleate). PET data showed flow-metabolism “mismatch;” whether regional or global,18FDG6P accumulation in ischemic tissue was the same as (glucose only) or significantly higher than (glucose + oleate) control tissue (0.023 ± 0.002 vs. 0.011 ± 0.002 normalized counts · s-1· g-1· min-1, P < 0.05) despite receiving 10% of the flow. This isolated rat heart model of acute hibernation exhibits many of the same characteristics demonstrated clinically in hibernating myocardium.

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Nicardipine normalizes elevated levels of antioxidant activity in response to xanthine oxidase-induced oxidative stress in hypertensive rat heart

Free Radical Research ◽

10.1080/10715769800300161 ◽

1998 ◽

Vol 29 (2) ◽

pp. 143-150 ◽

Cited By ~ 10

Author(s):

D.M. Carlos ◽

S. Goto ◽

Y. Urata ◽

T. Iida ◽

S. Cho ◽

...

Keyword(s):

Oxidative Stress ◽

Antioxidant Activity ◽

Xanthine Oxidase ◽

Rat Heart ◽

Hypertensive Rat

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Superoxide production by NAD(P)H oxidase and mitochondria is increased in genetically obese and hyperglycemic rat heart and aorta before the development of cardiac dysfunction. The role of glucose-6-phosphate dehydrogenase-derived NADPH

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01142.2008 ◽

2009 ◽

Vol 297 (1) ◽

pp. H153-H162 ◽

Cited By ~ 114

Author(s):

Sabrina Serpillon ◽

Beverly C. Floyd ◽

Rakhee S. Gupte ◽

Shimran George ◽

Mark Kozicky ◽

...

Keyword(s):

Cardiac Dysfunction ◽

Rat Heart ◽

Mitochondrial Respiratory Chain ◽

Posterior Wall ◽

Left Ventricular ◽

Posterior Wall Thickness ◽

Patients With Diabetes ◽

Protein Kinase C Inhibitor ◽

Glucose 6 Phosphate Dehydrogenase

Increased oxidative stress is a known cause of cardiac dysfunction in animals and patients with diabetes, but the sources of reactive oxygen species [e.g., superoxide anion (O2−)] and the mechanisms underlying O2− production in diabetic hearts are not clearly understood. Our aim was to determine whether NADPH oxidase (Nox) is a source of O2− and whether glucose-6-phosphate dehydrogenase (G6PD)-derived NADPH plays a role in augmenting O2− generation in diabetes. We assessed cardiac function, Nox and G6PD activities, NADPH levels, and the activities of antioxidant enzymes in heart homogenates from young (9–11 wk old) Zucker lean and obese (fa/fa) rats. We found that myocardial G6PD activity was significantly higher in fa/fa than in lean rats, whereas superoxide dismutase and glutathione peroxidase activities were decreased ( P < 0.05). O2− levels were elevated (70–90%; P < 0.05) in the diabetic heart, and this elevation was blocked by the Nox inhibitor gp-91ds-tat (50 μM) or by the mitochondrial respiratory chain inhibitors antimycin (10 μM) and rotenone (50 μM). Inhibition of G6PD by 6-aminonicotinamide (5 mM) and dihydroepiandrosterone (100 μM) also reduced ( P < 0.05) O2− production. Notably, the activities of Nox and G6PD in the fa/fa rat heart were inhibited by chelerythrine, a protein kinase C inhibitor. Although we detected no changes in stroke volume, cardiac output, or ejection fraction, left ventricular diameter was slightly increased during diastole and systole, and left ventricular posterior wall thickness was decreased during systole ( P < 0.05) in Zucker fa/fa rats. Our findings suggest that in a model of severe hyperlipidema and hyperglycemia Nox-derived O2− generation in the myocardium is fueled by elevated levels of G6PD-derived NADPH. Similar mechanisms were found to activate O2− production and induce endothelial dysfunction in aorta. Thus G6PD may be a useful therapeutic target for treating the cardiovascular disease associated with type 2 diabetes, if second-generation drugs specifically reducing the activity of G6PD to near normal levels are developed.

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