Left Ventricular Mechanoenergetics in Small Animals

Takaki, Miyako

doi:10.2170/jjphysiol.54.175

Cited by 32 publications

(67 citation statements)

References 219 publications

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“…As the balloon volume generally changed between 0 and 0.10 ml in Sham rats and between 0 and 0.20 ml in VO rats, respectively, we adopted mLVV normalized by LV mass to 1 g at balloon volume of 0.05 ml for Sham LVs and at balloon volume of 0.10 ml for VO LVs. We calculated ESP at mLVV (ESP mLVV) and PVA at mLVV (PVAmLVV) to assess LV mechanical work and energetics in the two groups.As shown previously (14,17,19,24), the V O2-PVA relationship was linear in the rat LV. Its slope represents the O2 cost of PVA, and Values are means Ϯ SD; n ϭ 7 Sham rats and 7 volume overload (VO) rats.…”

supporting

confidence: 83%

“…However, the cardiac mechanoenergetics studies have not yet been well conducted. We have established a method to analyze specifically the LV mechanical work and energetics in an excised, blood-perfused whole heart preparation with a cross-circulation method (7,14,17,19,20,24) and analyzed LV mechanoenergetics in a PO heart failure model.In the present study, we focused on the investigation of the mechanical work and energetics in a VO heart failure model with an arteriovenous (AV) shunt in rats. …”

mentioning

confidence: 99%

“…All rats were heparinized (1,000 units intravascular). The beating donor heart was excised without an interruption of coronary perfusion and supported by cross circulation with the other metabolic supporter rat as previously reported in detail (7,14,17,19,24). The coronary arterial oxygenated blood of the donor heart was supplied from the common carotid arteries of the supporter rat using arterial cross-circulation tubing and a cannula inserted into the brachiocephalic artery of the donor heart.…”

mentioning

confidence: 99%

“…LV thebesian flow is negligible. The coronary AVO 2D was continuously measured by passing all the arterial and venous cross-circulation blood through the cuvettes of a custom-made AVO 2D analyzer (PWA-200S, Shoe Technica; Chiba, Japan) as previously reported in detail (14,17,19,24).Calculation of PVA. PVA was defined as the systolic PVA circumscribed by the curvilinear ESPVR, the EDPVR, and the systolic portion of the ventricular pressure-volume trajectory and was obtained by the integration of ESPVR and EDPVR.…”

mentioning

confidence: 99%

“…The areas under the ESPVR and EDPVR were obtained by the integration of the best-fit exponential functions. Based on our previous publications (14,17,19,24), we obtained control ESPVR and determined a midrange LV volume (mLVV) under which contractility changes in response to Ca 2ϩ infusion (16). As the balloon volume generally changed between 0 and 0.10 ml in Sham rats and between 0 and 0.20 ml in VO rats, respectively, we adopted mLVV normalized by LV mass to 1 g at balloon volume of 0.05 ml for Sham LVs and at balloon volume of 0.10 ml for VO LVs.…”

mentioning

confidence: 99%

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Mechanical work and energetic analysis of eccentric cardiac remodeling in a volume overload heart failure in rats

Takewa

Chemaly²,

Takaki³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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Eccentric cardiac remodeling seen in dilated cardiomyopathy or regurgitant valvular disease is a well-known process of heart failure progression, but its mechanoenergetic profile has not been yet established. We made a volume overload (VO) heart failure model in rats and for the first time investigated left ventricular (LV) mechanical work and energetics in cross-circulated whole heart preparations. Laparotomy was performed in 14 Wistar male rats, and abdominal aortic-inferior vena caval shunt was created in seven rats (VO group). Another seven rats underwent a sham operation without functional shunt (Sham group). LV dimensions changes were followed with weekly transthoracic echocardiography. Three months after surgery, we measured LV pressure and volume and myocardial O2 consumption in isolated heart cross circulation. LV internal dimensions in both systolic and diastolic phases were significantly increased in the VO group versus the Sham group (P Ͻ 0.05). LV pressure was markedly decreased in the VO group versus in the Sham group (P Ͻ 0.05). LV end-systolic pressurevolume relation shifted downward, and myocardial O2 consumption related to Ca 2ϩ handling significantly decreased. The contractile response to Ca 2ϩ infusion was attenuated. Nevertheless, the increase in Ca 2ϩ handling-related O2 consumption per unit change in LV contractility in the VO group was significantly higher than that in the Sham group (P Ͻ 0.05). The levels of sarco(endo)plasmic reticulum Ca 2ϩ -ATPase 2a protein were reduced in the VO group (P Ͻ 0.01). In conclusion, VO failing rat hearts had a character of marked contractile dysfunction accompanied with less efficient energy utilization in the Ca 2ϩ handling processes. These results suggest that restoring Ca 2ϩ handling in excitation-contraction coupling would improve the contractility of the myocardium after eccentric cardiac remodeling. eccentric left ventricular hypertrophy; myocardial oxygen consumption; Ca 2ϩ handling; sarco(endo)plasmic reticulum Ca 2ϩ -ATPase 2a; cross circulation; aortocaval shunt HEART FAILURE IS A MAJOR CAUSE of mortality and morbidity. It is due to various diseases such as hypertension, ischemic heart disease, valvular heart disease, congenital heart disease, cardiomyopathy, myocarditis, and others. The heart is subject to excessive and/or long-term overload, which induces myocardial hypertrophy. Hypertrophy initially compensates cardiac function but finally leads to heart failure. The process of hypertrophy and heart failure progression is divided into two mechanisms, depending on the type of overload: pressure overloading (PO) and volume overloading (VO). PO induces concentric hypertrophy to normalize wall stress from the increase in pressure placed on cardiomyocytes. Concentric remodeling of the left ventricle (LV) is characterized by an increase in ventricular wall thickness due to vertical growing of cardiomyocytes, which is caused by the parallel addition of sarcomeres (8).Conversely, VO promotes eccentric hypertrophy to compensate for excess blood volum...

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supporting

confidence: 83%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Mechanical work and energetic analysis of eccentric cardiac remodeling in a volume overload heart failure in rats

Takewa

Chemaly²,

Takaki³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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Models of the Heart

Furst

2013

The Heart and Circulation

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Methods for the Preparation of an Excised, Cross-Circulated Rat Heart

Okihara

Takaki

2018

Methods in Molecular Biology

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The Emax-Pressure-Volume Area (PVA)-VO framework proposed by Dr. Suga for canine hearts has dramatically advanced the field of cardiac mechanical work and energetics, i.e., mechanoenergetics. He and his collaborators investigated mechanoenergetics in the left ventricle (LV) of excised, cross-circulated canine heart preparations. We instituted the excised cross-circulated rat whole heart preparations and found a curvilinear end-systolic pressure-volume relation (ESPVR) in the rat LV, in contrast to the linear ESPVR in canine, rabbit, and human LVs. Although Emax, the slope of the linear ESPVR, could be used as an index of LV contractility, it was not applicable for evaluating LV contractility in the rat LV. Thus, we proposed a new index of contractility, equivalent Emax (eEmax) in the rat LV. We also found a linear VO-PVA relationship in the rat LV. Here, we introduce the methods for the preparation of excised, cross-circulated rat whole hearts and the eEmax-PVA-VO framework in the rat LV. Using this method, we can obtain accurate LV volume and myocardial O consumption in real time for estimating cardiac mechanoenergetics, which is very challenging in in vivo experiments.

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Left Ventricular Mechanoenergetics in Small Animals

Cited by 32 publications

References 219 publications

Mechanical work and energetic analysis of eccentric cardiac remodeling in a volume overload heart failure in rats

Mechanical work and energetic analysis of eccentric cardiac remodeling in a volume overload heart failure in rats

Models of the Heart

Methods for the Preparation of an Excised, Cross-Circulated Rat Heart

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