What question did this study set out to answer?

To determine the quantities of free calcium required to activate cardiac myofibrils, drive ATPase activity, and generate isometric tension in the myocardium.

April 1, 1974Circulation ResearchOpen Access

Calcium Requirements for Cardiac Myofibrillar Activation

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Population

Dog heart myofibrils

Design

Preclinical

Authors

RSR. John SolaroGeneral Cardiology RWRobert M. WiseGeorge Washington University JSJ. S. ShinerUniversity of Bern

Discussion

Member takes

Implication

Provides calcium thresholds for tension in canine myocardium; leaves open translation to human contractile regulation.

Key Points

To determine the quantities of free calcium required to activate cardiac myofibrils, drive ATPase activity, and generate isometric tension in the myocardium.
Measured the dependence of myofibrillar calcium binding, myofibrillar ATPase activity, and isometric tension generation across a range of free calcium concentrations in dog cardiac tissue.
Quantified total myofibrillar protein content in dog myocardium (47.5 mg/g wet heart) to calculate calcium activation thresholds in the intact ventricle.
Myofibrillar ATPase activity and isometric tension development reached half-maximal levels at 2.4 x 10^-6 M and 2.0 x 10^-6 M free calcium, respectively.
Substantial calcium binding occurred between 10^-8 M and 10^-6 M free calcium without tension generation, and binding was not saturated at maximal tension, indicating only a subset of binding sites regulates contraction.
In the intact ventricle, generating half-maximal tension required 22.4 µmoles calcium/kg wet heart, whereas maximal isometric tension required 92.8 µmoles calcium/kg wet heart.

Structured PICO

Population

Dog heart myofibrils

Intervention

Varying free calcium concentrations

Outcome

Dependence of myofibrillar calcium binding, myofibrillar ATPase, and isometric tension on free calcium concentrationsurrogate

This preclinical study quantified the specific calcium requirements for myofibrillar activation and tension development in the intact dog ventricle.

Cite This Study

Solaro et al. (1974) studied this question.

synapsesocial.com/papers/6a7baca4351d91d38cc62c42 https://doi.org/10.1161/01.res.34.4.525

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Calcium Requirements for Cardiac Myofibrillar Activation

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Calcium Requirements for Cardiac Myofibrillar Activation

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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