scholarly journals Heart failure switches the RV α1-adrenergic inotropic response from negative to positive

2010 ◽  
Vol 298 (3) ◽  
pp. H913-H920 ◽  
Author(s):  
Guan-Ying Wang ◽  
Che-Chung Yeh ◽  
Brian C. Jensen ◽  
Michael J. Mann ◽  
Paul C. Simpson ◽  
...  
Keyword(s):  
Heart Failure ◽  
Clinical Problem ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Left Ventricular Myocardium ◽  
Coronary Artery Ligation ◽  
Inotropic Response ◽  
Artery Ligation ◽  
Protein Levels ◽  
Inotropic Responses

Right ventricular (RV) failure is a serious common clinical problem that is poorly understood. Therefore, for failing and nonfailing hearts, we examined the distinctive inotropic responses induced in the RV myocardium after the stimulation of α1-adrenergic receptors (ARs). In RV trabeculae from nonfailing mouse hearts, α1-ARs induced a negative inotropic response, consistent with our previous study. In marked contrast, in RV trabeculae from failing hearts, 12 wk after coronary artery ligation, α1-ARs induced a positive inotropic response. Mechanistically, experiments with skinned trabeculae showed that α1-ARs decreased myofilament Ca2+ sensitivity in the nonfailing RV myocardium, whereas α1-ARs increased Ca2+ sensitivity in heart failure. This suggests that a switch in the Ca2+ sensitivity response to α1-AR stimulation explained the switch in the RV α1-AR inotropic response in heart failure. Myosin light chain kinase (MLCK) can increase myofilament Ca2+ sensitivity, and the smooth muscle isoform (smMLCK), which is also present in cardiomyocytes, was more abundant in the RV myocardium from failing versus nonfailing hearts. Moreover, the MLCK inhibitor ML-9 prevented the switch of the RV myocardium to a positive α1-AR inotropic response in heart failure. In the left ventricular myocardium, in contrast, α1-AR inotropic responses were not different in failing versus nonfailing hearts, and smMLCK abundance was not increased in heart failure. In relation to human disease, we found that smMLCK mRNA and protein levels were increased in RVs from failing human hearts. We conclude that the RV inotropic response to α1-ARs is switched from negative to positive in heart failure, through a pathway involving increased myofilament Ca2+ sensitivity. Since α1-AR agonist catecholamines are elevated in heart failure, increased α1-AR inotropic responses in the RV myocardium may be adaptive in heart failure by helping the failing RV respond to increased pulmonary pressures.

Abstract P237: Is Ischemia/Reperfusion an Efficient Method for Producing Heart Failure in Rats?

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Ana Carolina M Omoto ◽  
Fábio N Gava ◽  
Mauro de Oliveira ◽  
Carlos A Silva ◽  
Rubens Fazan ◽  
...  
Keyword(s):  
Heart Failure ◽  
Diastolic Pressure ◽  
Histopathological Examination ◽  
Ischemia Reperfusion ◽  
Mitral Annulus ◽  
Mortality Rates ◽  
Tissue Doppler ◽  
Left Ventricular ◽  
Coronary Artery Ligation ◽  
Artery Ligation

Myocardium infarction (MI) elicited by coronary artery ligation (CAL) is commonly used to induce chronic heart failure (HF) in rats. However, CAL shows high mortality rates. Given that ischemia-reperfusion (IR) may cause the development of HF, this approach may be useful for obtaining a model of HF with low mortality rates. Therefore, it was compared the model of CAL vs. IR in rats, evaluating the mortality and cardiac morphological and functional aspects. The IR consisted of 30 minutes of cardiac ischemia. Wistar rats were assigned into three groups: CAL: n=18; IR: n=7; SHAM (fictitious IR): n=7. After four weeks of CAL, the subjects were evaluated by echocardiography and ventriculography as well. The statistical analysis consisted of ANOVA combined with Tukey’s posthoc test (p<0.05). There were no deaths in the IR and SHAM groups, whereas in the CAL group the mortality rate was 33.33% (6 out of 18). In the CAL group echocardiography showed increased left ventricular (LV) cavity during systole (8.3 ± 1mm) and diastole (10.5 ± 1mm); decreased LV free wall during systole (1.4 ± 0.5 mm); increased left atrium/aorta (2.3 ± 0.4) ratio. These changes were not significant in IR (4.8 ± 0.5mm, 7.6 ± 0.6mm, 2.6 ± 0.3 mm, 1.6 ± 0.2) and SHAM (4.6 ± 0.6 mm, 7.7 ± 0.8mm, 2.8 ± 0.4mm, 1.5 ± 0.2) groups. There was also the reduction in the ejection fraction in the CAL group (41 ± 12 %) when compared with IR (65 ± 9%) and SHAM (69 ± 7%) groups. The tissue Doppler analysis from the lateral mitral annulus showed reduction in E′ in CAL (-29 ± 8 mm/s) and IR (-31± 9 mm/s) groups when compared with the SHAM (-48 ± 11 mm/s) group. The ventriculography in the CAL group showed smaller maximum dP/dt (6519 ± 1062) and greater end-diastolic pressure (33 ± 8 mmHg) when compared with IR (8716 ± 756 mmHg/s; 9 ± 9 mmHg) and SHAM (7989 ± 1230 mmHg/s; 9 ± 7 mmHg) groups. The CAL group presented transmural infarct size of 40% of the left ventricular wall, measured under histopathological examination. In conclusion, IR for 30 minutes caused only small changes in LV diastolic function, assessed by tissue Doppler; however, the IR was not effective for promoting HF, as observed with CAL. Thus, it is possible that prolonged IR is necessary for promoting significant HF in rats.

Regulation of K+ and Ca2+ channels in experimental cardiac failure

1991 ◽  
Vol 261 (6) ◽  
pp. H1979-H1987 ◽  
Author(s):  
M. Gopalakrishnan ◽  
D. J. Triggle ◽  
A. Rutledge ◽  
Y. W. Kwon ◽  
J. A. Bauer ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Right Ventricle ◽  
Cardiac Failure ◽  
Radioligand Binding ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
The Right

To examine the status of ATP-sensitive K+ (K+ATP) channels and 1,4-dihydropyridine-sensitive Ca2+ (Ca2+DHP) channels during experimental cardiac failure, we have measured the radioligand binding properties of [3H]glyburide and [3H]PN 200 110, respectively, in tissue homogenates from the rat cardiac left ventricle, right ventricle, and brain 4 wk after myocardial infarction induced by left coronary artery ligation. The maximal values (Bmax) for [3H]glyburide and [3H]PN 200 110 binding were reduced by 39 and 40%, respectively, in the left ventricle, and these reductions showed a good correlation with the right ventricle-to-body weight ratio in heart-failure rats. The ligand binding affinities were not altered. In the hypertrophied right ventricle, Bmax values for both the ligands were not significantly different when data were normalized to DNA content or right ventricle weights but showed an apparent reduction when normalized to unit protein or tissue weight. Moderate reductions in channel densities were observed also in whole brain homogenates from heart failure rats. Assessment of muscarinic receptors, beta-adrenoceptors and alpha 1-adrenoceptors by [3H]quinuclidinyl benzilate, [3H]dihydroalprenolol, and [3H]prazosin showed reductions in left ventricular muscarinic and beta-adrenoceptor densities but not in alpha 1-adrenoceptor densities, consistent with earlier observations. It is suggested that these changes may in part contribute to the pathology of cardiac failure.

scholarly journals Exertional dyspnea after myocardial infarction: thinking beyond the diagnosis of heart failure

2018 ◽  
Vol 46 (11) ◽  
pp. 4769-4774
Author(s):  
Konstantinos Koutsampasopoulos ◽  
Savvas Grigoriadis ◽  
Ioannis Vogiatzis
Keyword(s):  
Myocardial Infarction ◽  
Heart Failure ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Left Ventricular Aneurysm ◽  
Left Ventricular Myocardium ◽  
Inferior Wall ◽  
Delayed Presentation ◽  
Exertional Dyspnea ◽  
St Elevation

Introduction We herein present an unusual case of a pseudoaneurysm of the left ventricular myocardium, which is a rare and fatal complication of myocardial infarction. Case report A 64-year-old man with a history of bipolar disorder and arterial hypertension was hospitalized for delayed presentation ST-elevation myocardial infarction. He was admitted to our hospital 24 hours after symptom onset. Diagnostic coronary angiography revealed 95% stenosis at the distal third of the right coronary artery, and he underwent a primary percutaneous coronary intervention to the culprit lesion. Despite administration of a diuretic and optimization of other pharmaceutical treatment, his heart failure deteriorated. Electrocardiography showed a sinus rhythm with Q-wave formation in the inferior wall leads (II, III, aVF), T-wave inversion in the same leads, and borderline QT prolongation (QTc of 490 ms). No ST elevation suggestive of left ventricular aneurysm formation was noticed. Forty days later, cardiac ultrasound revealed a dyskinetic cavity (pseudoaneurysm) in continuity with the posterior–inferior wall of the myocardium, resulting in severe mitral valve regurgitation. Unfortunately, the patient died while awaiting surgical treatment. Conclusion Although most patients with left ventricular pseudoaneurysm have a relatively benign outcome, those with symptoms of heart failure must be urgently diagnosed and treated.

Deloading of the Left Ventricle by Ventricular Assist Device Normalizes Increased Expression of Endothelin ET A Receptors But Not Endothelin-Converting Enzyme-1 in Patients With End-Stage Heart Failure

Circulation ◽  
2000 ◽  
Vol 102 (suppl_3) ◽  
Author(s):  
Henning Morawietz ◽  
Marten Szibor ◽  
Winfried Goettsch ◽  
Babett Bartling ◽  
Matthias Barton ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Transplantation ◽  
Ace Inhibitor ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Left Ventricular Myocardium ◽  
Converting Enzyme ◽  
Ventricular Assist ◽  
End Stage Heart Failure ◽  
End Stage

Background —Ventricular assist devices (VAD) are implanted in patients with end-stage heart failure for bridging the time until heart transplantation, resulting in hemodynamic unloading of the failing heart, improved cardiac contractile and mitochondrial function, and reversal of cardiac hypertrophy. It is unknown whether VAD unloading may affect the cardiac endothelin (ET) system, which has been proposed as one of the putative pathomechanisms of heart failure. Methods and Results —With the use of standard-calibrated, competitive reverse-transcription–polymerase chain reaction mRNA expression of components of the ET system was analyzed in left ventricular myocardium from nonfailing donor hearts, from failing hearts without and with ACE inhibitor therapy, and from patients with end-stage heart failure at the time of VAD implantation and 103±15 days after VAD implantation during removal with subsequent heart transplantation. ET receptor A (ET A ) was markedly upregulated in failing human myocardium. This increased ET A expression was not affected by ACE inhibitor treatment but was normalized by VAD unloading. ET A expression before or after VAD implantation did not correlate with duration of VAD implantation or suppression of Pro-ANP mRNA. ET B mRNA expression was unaffected by heart failure or VAD. In contrast, increased ET-converting enzyme-1 mRNA and ET-1 peptide levels in failing myocardium were partially normalized by ACE inhibition but not by VAD unloading. Conclusions —We conclude that VAD implantation normalizes ET A expression in failing human left ventricular myocardium, probably as the result of the beneficial effects of VAD unloading.

Reductions of myocardial Na-K-ATPase activity and ouabain binding sites in heart failure: prevention by nadolol

1993 ◽  
Vol 265 (6) ◽  
pp. H2086-H2093 ◽  
Author(s):  
T. H. Fan ◽  
R. P. Frantz ◽  
H. Elam ◽  
S. Sakamoto ◽  
N. Imai ◽  
...  
Keyword(s):  
Heart Failure ◽  
Atpase Activity ◽  
Binding Sites ◽  
Early Stage ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Left Ventricular Myocardium ◽  
Adrenergic Stimulation ◽  
Ouabain Binding ◽  
Systemic Hemodynamic

To study the changes in myocardial digitalis binding sites in heart failure, we measured myocardial ouabain binding sites, Na-K-adenosinetriphosphatase (ATPase) activity, and ventricular muscle mechanical responses to acetylstrophanthidin in dogs with right-heart failure (RHF) produced by tricuspid avulsion and pulmonary artery constriction. Sham-operated dogs were studied as the control. RHF produced a significant decrease in ouabain binding sites in the right and left ventricular myocardium, which was accompanied by a proportional decrease in Na-K-ATPase activity. However, RHF and sham-operated dogs did not differ in systemic hemodynamic or right ventricular trabeculate muscle isometric contractile responses to acetylstrophanthidin. To determine whether chronic beta-adrenergic stimulation contributed to the development of Na-K-ATPase downregulation, we administered nadolol (40 mg/day) to a separate group of dogs during an early stage of RHF development. Nadolol effectively prevented the reduction of myocardial ouabain binding sites that occurred in RHF. Thus we conclude that myocardial ouabain binding sites and Na-K-ATPase activity are reduced in dogs with experimental heart failure and that these changes probably occur as a result of the attendant heightened sympathetic activity.

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