The Inverse Relationship between Cardiac Muscle Stress and Cross-Sectional Area Is Preserved in Ba2+ Contracture and in Chemically-Permeabilised Ca2+ Contracture

Choi, Do Il; Pham, Toan; Loiselle, Denis S.; Taberner, Andrew J.; Han, June‐Chiew; Tran, Kenneth

doi:10.1007/s11340-020-00652-y

Cited by 7 publications

(9 citation statements)

References 46 publications

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“…Experiments were conducted on the Muscle Mechanometer, a previously-described custom device ( Choi et al, 2021 ; Musgrave et al, 2023 ). Permeabilised trabeculae were mounted in a tissue bath filled with relaxing solution between a voice-coil motor and stainless-steel cantilever.…”

Section: Methodsmentioning

confidence: 99%

Analysis of metabolite and strain effects on cardiac cross-bridge dynamics using model linearisation techniques

Musgrave,

Han,

Ward

et al. 2024

Front. Physiol.

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Multi-scale models of cardiac energetics are becoming crucial in better understanding the prevalent chronic diseases operating at the intersection of metabolic and cardiovascular dysfunction. Computationally efficient models of cardiac cross-bridge kinetics that are sensitive to changes in metabolite concentrations are necessary to simulate the effects of disease-induced changes in cellular metabolic state on cardiac mechanics across disparate spatial scales. While these models do currently exist, deeper analysis of how the modelling of metabolite effects and the assignment of strain dependence within the cross-bridge cycle affect the properties of the model is required. In this study, model linearisation techniques were used to simulate and interrogate the complex modulus of an ODE-based model of cross-bridge kinetics. Active complex moduli were measured from permeabilised rat cardiac trabeculae under five different metabolite conditions with varying ATP and Pi concentrations. Sensitivity to metabolites was incorporated into an existing three-state cross-bridge model using either a direct dependence or a rapid equilibrium approach. Combining the two metabolite binding methods with all possible locations of strain dependence within the cross-bridge cycle produced 64 permutations of the cross-bridge model. Using linear model analysis, these models were systematically explored to determine the effects of metabolite binding and their interaction with strain dependence on the frequency response of cardiac muscle. The results showed that the experimentally observed effects of ATP and Pi concentrations on the cardiac complex modulus could be attributed to their regulation of cross-bridge detachment rates. Analysis of the cross-bridge models revealed a mechanistic basis for the biochemical schemes which place Pi release following cross-bridge formation and ATP binding prior to cross-bridge detachment. In addition, placing strain dependence on the reverse rate of the cross-bridge power stroke produced the model which most closely matched the experimental data. From these analyses, a well-justified metabolite-sensitive model of rat cardiac cross-bridge kinetics is presented which is suitable for parameterisation with other data sets and integration with multi-scale cardiac models.

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Section: Methodsmentioning

confidence: 99%

Analysis of metabolite and strain effects on cardiac cross-bridge dynamics using model linearisation techniques

Musgrave,

Han,

Ward

et al. 2024

Front. Physiol.

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“…The steady-state force-Ca 2+ relations and, therefore, myofilament sensitivity, measured using intact and skinned samples are not equivalent, with intact samples appearing to have a greater Ca 2+ sensitivity ( Gao et al, 1994 ; Varian et al, 2006 ). However, skinning does not appear to negatively affect the maximum force production of cardiac muscle ( Choi et al, 2020 ). The discrepancy in Ca 2+ sensitivity has instead been speculatively attributed to a loss of post-translational modifications caused by the permeabilisation process ( Chung et al, 2016 ).…”

Section: Steady-state Force-ca 2+ Relationmentioning

confidence: 99%

Methods for assessing cardiac myofilament calcium sensitivity

Dowrick,

Taberner,

Han

et al. 2023

Front. Physiol.

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Myofilament calcium (Ca2+) sensitivity is one of several mechanisms by which force production of cardiac muscle is modulated to meet the ever-changing demands placed on the heart. Compromised Ca2+ sensitivity is associated with pathologies, which makes it a parameter of interest for researchers. Ca2+ Sensitivity is the ratio of the association and dissociation rates between troponin C (TnC) and Ca2+. As it is not currently possible to measure these rates in tissue preparations directly, methods have been developed to infer myofilament sensitivity, typically using some combination of force and Ca2+ measurements. The current gold-standard approach constructs a steady-state force-Ca2+ relation by exposing permeabilised muscle samples to a range of Ca2+ concentrations and uses the half-maximal concentration as a proxy for sensitivity. While a valuable method for steady-state investigations, the permeabilisation process makes the method unsuitable when examining dynamic, i.e., twitch-to-twitch, changes in myofilament sensitivity. The ability of the heart to transiently adapt to changes in load is an important consideration when evaluating the impact of disease states. Alternative methods have been proffered, including force-Ca2+ phase loops, potassium contracture, hybrid experimental-modelling and conformation-based fluorophore approaches. This review provides an overview of the mechanisms underlying myofilament Ca2+ sensitivity, summarises existing methods, and explores, with modelling, whether any of them are suited to investigating dynamic changes in sensitivity. We conclude that a method that equips researchers to investigate the transient change of myofilament Ca2+ sensitivity is still needed. We propose that such a method will involve simultaneous measurements of cytosolic Ca2+ and TnC activation in actively twitching muscle and a biophysical model to interpret these data.

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“…Impacts on the skin and slows down nerve conduction. Chronic contact with arsenic can occasionally be lethal and cause lung cancer [36]. Lead (Pb) Kidneys, reproductive systems, and neurological connections could all be affected.…”

Section: No Hazardous Elements Detrimental Effects Of the Hazardous E...mentioning

confidence: 99%

“…To improve environmentally friendly e-waste management in India, more money, infrastructure, and incentives are required. Figure 4A provides data outlining the projected e-waste generation in million metric tonnes (MMT) for several years from 2015 to 2050 [36]. Figure 4B shows the import profile of EEE in India from year 2014 to 2022 [36].…”

Section: Current E-waste Management In Indiamentioning

confidence: 99%

“…Figure 4A provides data outlining the projected e-waste generation in million metric tonnes (MMT) for several years from 2015 to 2050 [36]. Figure 4B shows the import profile of EEE in India from year 2014 to 2022 [36]. Figure 5A presents state-wise data on e-waste generators, revealing regional disparities in electronic waste production [35].…”

Section: Current E-waste Management In Indiamentioning

confidence: 99%

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An Integrated Approach for Electronic Waste Management—Overview of Sources of Generation, Toxicological Effects, Assessment, Governance, and Mitigation Approaches

Nandan,

Suresh,

Saole

et al. 2023

Sustainability

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Electronic waste (e-waste) management has become a significant challenge in recent years due to the increasing consumption of electronic devices and their improper disposal. Effective e-waste management requires a comprehensive approach that considers the environmental, economic, and social impacts of e-waste. This comprehensive review provides a critical assessment of e-waste management procedures, encompassing the stages of collection, transportation, treatment, and disposal. Emphasising the significance of embracing sustainable approaches like reusing, repairing, and recycling, the review underscores their pivotal role in mitigating the adverse environmental and human health effects of e-waste. This review provides an overview of e-waste management concerns specifically in India from its collection to the end cycle including toxicological, environmental, and human impacts and a graphical analysis of current and future e-waste trends. It emphasises the need to effectively enforce regulations and establish extended producer responsibility (EPR) to promote sustainable e-waste management practices. Additionally, the review delves into the complexities surrounding e-waste management, such as insufficient infrastructure, resource and funding constraints, and a dearth of awareness among stakeholders. It strongly underscores the necessity for a concerted endeavour involving governments, industries, and communities to tackle these obstacles and advance the cause of efficient e-waste management practices. This paper is valuable to the scientific community as it offers a thorough assessment of e-waste management, focusing on environmental, economic, and social impacts. It emphasises sustainable practices and regulatory measures, providing actionable insights to address e-waste challenges. Overall, this review provides a comprehensive overview of e-waste management and highlights the importance of adopting sustainable practices to address the negative impacts of e-waste on the environment, human health, and the economy.

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The Inverse Relationship between Cardiac Muscle Stress and Cross-Sectional Area Is Preserved in Ba2+ Contracture and in Chemically-Permeabilised Ca2+ Contracture

Cited by 7 publications

References 46 publications

Analysis of metabolite and strain effects on cardiac cross-bridge dynamics using model linearisation techniques

Analysis of metabolite and strain effects on cardiac cross-bridge dynamics using model linearisation techniques

Methods for assessing cardiac myofilament calcium sensitivity

An Integrated Approach for Electronic Waste Management—Overview of Sources of Generation, Toxicological Effects, Assessment, Governance, and Mitigation Approaches

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