In a healthy human heart, an increase in heart rate results in an increase in force of contractions (positive force-frequency relationship, or FFR), and an acceleration of contractile kinetics (frequency-dependent acceleration of relaxation, or FDAR). In human heart failure, the FFR flattens or even becomes negative, while FDAR greatly diminishes; these two phenomena are classic hallmarks of heart failure. Despite its critical role in health and disease, frequency- dependent modulation of contraction and kinetics is poorly understood. The magnitude in contractile response to frequency response in mice is >10 times smaller than in humans, and most often even completely absent. This necessitates the investigation of frequency-dependent processes of contraction and kinetics in a large animal model, or better yet, in human myocardium. Guided by the literature, our own data, and the last 5 years of preliminary data from experiments on human heart tissue and its frequency-dependent regulation, we recently wrote a very extensive review that postulates the hypothesis that the kinetics of relaxation are governed by three interdependent processes: intracellular calcium decline, myofilament calcium binding kinetics, and cross-bridge cycling kinetics. Currently, there is a vast vacuum of data regarding the kinetic rate and regulation in human myocardium, which is critical, since data from the 10-times faster murine myocardium are nearly impossible to interpret in the context of the prevailing rates in the human. We have constructed aims that 1) first establish the kinetic rates for the three processes that govern relaxation in failing and non-failing human myocardium, and then proceed to 2) modify this kinetic rate by engineering a different myofilament calcium sensitivity in human failing and non-failing myocardium. In the first aim, we will assess the kinetic rates of calcium transient decline, myofilament responsiveness, and cross-bridge cycling kinetics in non-failing and failing human myocardium, in the second aim, we will assess whether modification of the kinetic rate governing myofilament calcium responsiveness can restore the FDAR in failing human myocardium by employing engineered TroponinC proteins. The above aims will be carried out in n>50 failing and n>50 non-failing human hearts. This will allow us to eventually perform a differential analysis based on disease etiology. Based on our experience in working with human hearts we will have sufficient statistical power to distinguish outcomes between hearts classified as ischemic-cardiomyopathy, dilated-cardiomyopathy, and those with a primary diastolic dysfunction.

Public Health Relevance

Knowledge necessary in order to strategize potential treatments of cardiac contractile dysfunction is currently critically lacking. In this project, we propose to provide data omn the rate limiting steps that govern the relaxation phase of the heart. The human hearts beats ~10 times slower than a mouse heart, and thus specifically processes related to the speed of contraction and relaxation are vastly different in mouse versus human. We propose to assess the contraction force and speed of healthy and end-stage failing human hearts, and investigate and quantify in depth the processes that contribute to the regulation of contractile kinetics. We will then proceed to investigate whether an engineered protein, with a directed mutation in calcium binding properties can improve contraction and relaxation in the human failing heart. We will accomplish the above project using ~150 human hearts over 5 years.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL113084-08
Application #
9754855
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Desvigne-Nickens, Patrice
Project Start
2012-08-15
Project End
2020-07-31
Budget Start
2019-08-01
Budget End
2020-07-31
Support Year
8
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Ohio State University
Department
Physiology
Type
Schools of Medicine
DUNS #
832127323
City
Columbus
State
OH
Country
United States
Zip Code
43210
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Chung, Jae-Hoon; Martin, Brit L; Canan, Benjamin D et al. (2018) Etiology-dependent impairment of relaxation kinetics in right ventricular end-stage failing human myocardium. J Mol Cell Cardiol 121:81-93
Milani-Nejad, Nima; Chung, Jae-Hoon; Canan, Benjamin D et al. (2018) Increased cross-bridge recruitment contributes to transient increase in force generation beyond maximal capacity in human myocardium. J Mol Cell Cardiol 114:116-123
Janssen, Paul M L; Canan, Benjamin D; Kilic, Ahmet et al. (2018) Human Myocardium Has a Robust ?1A-Subtype Adrenergic Receptor Inotropic Response. J Cardiovasc Pharmacol 72:136-142
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Slabaugh, Jessica L; Brunello, Lucia; Elnakish, Mohammad T et al. (2018) Synchronization of Intracellular Ca2+ Release in Multicellular Cardiac Preparations. Front Physiol 9:968
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Csepe, Thomas A; Zhao, Jichao; Sul, Lidiya V et al. (2017) Novel application of 3D contrast-enhanced CMR to define fibrotic structure of the human sinoatrial node in vivo. Eur Heart J Cardiovasc Imaging 18:862-869
Elnakish, Mohammad T; Canan, Benjamin D; Kilic, Ahmet et al. (2017) Effects of zacopride, a moderate IK1 channel agonist, on triggered arrhythmia and contractility in human ventricular myocardium. Pharmacol Res 115:309-318
Ackermann, Maegen A; Petrosino, Jennifer M; Manring, Heather R et al. (2017) TGF-?1 affects cell-cell adhesion in the heart in an NCAM1-dependent mechanism. J Mol Cell Cardiol 112:49-57

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