Resting metabolism of mouse papillary muscle

Widén, Cecilia; Barclay, Christopher John

doi:10.1007/s00424-005-1408-4

Cited by 13 publications

(15 citation statements)

References 34 publications

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“…Conventionally, muscle calorimeters have been required to be completely immersed in a temperature controlled water bath or to be in a chamber heated by temperature-controlled water flow (6,7,9,38). In contrast, our calorimeter has a multilevel temperature control system using both thermoelectric modules and a resistive heater.…”

Section: Discussionmentioning

confidence: 99%

A high-resolution thermoelectric module-based calorimeter for measuring the energetics of isolated ventricular trabeculae at body temperature

Johnston

Han

Ruddy

et al. 2015

American Journal of Physiology-Heart and Circulatory Physiology

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Johnston CM, Han JC, Ruddy BP, Nielsen PM, Taberner AJ. A high-resolution thermoelectric module-based calorimeter for measuring the energetics of isolated ventricular trabeculae at body temperature. Am J Physiol Heart Circ Physiol 309: H318 -H324, 2015. First published May 22, 2015; doi:10.1152/ajpheart.00194.2015.-Isolated ventricular trabeculae are the most common experimental preparations used in the study of cardiac energetics. However, the experiments have been conducted at subphysiological temperatures. We have overcome this limitation by designing and constructing a novel calorimeter with sufficiently high thermal resolution for simultaneously measuring the heat output and force production of isolated, contracting, ventricular trabeculae at body temperature. This development was largely motivated by the need to better understand cardiac energetics by performing such measurements at body temperature to relate tissue performance to whole heart behavior in vivo. Our approach uses solid-state thermoelectric modules, tailored for both temperature sensing and temperature control. The thermoelectric modules have high sensitivity and low noise, which, when coupled with a multilevel temperature control system, enable an exceptionally high temperature resolution with a noise-equivalent power an order of magnitude greater than those of other existing muscle calorimeters. Our system allows us to rapidly and easily change the experimental temperature without disturbing the state of the muscle. Our calorimeter is useful in many experiments that explore the energetics of normal physiology as well as pathophysiology of cardiac muscle. muscle energetics; microcalorimetry; heat production NEW & NOTEWORTHY We have developed a new muscle calorimeter, which has enabled the first simultaneous measurements of the force and heat output of isolated, actively contracting, cardiac trabeculae at body temperature. This was achieved by the use of thermoelectric modules for high-resolution temperature sensing and precise temperature control.MEASUREMENTS OF THE ENERGETICS of cardiac muscle under controlled experimental conditions, and in particular at body temperature, enable better understanding of cardiac muscle function in health and disease. Studies of force production simultaneous with heat output of cardiac muscle require the use of isolated tissue preparations such as small papillary muscles (2-4, 12, 26, 34) or trabeculae carneae (17-21) as they are sufficiently small to avoid muscle anoxia (14). The use of these tissue preparations, which have approximately one-dimensional arrangements of myocytes, simplifies the interpretation of measurements. Although these tissue studies have improved our understanding of myocardial energetics, previous experiments have been performed only at subphysiological temperatures, typically 10°C below that of body temperature (3,5,10,11,13,23,25,26,28,30,31). One exception is the study by Widén (39), who made simultaneous force and heat measurements in mouse papillary muscles at body temperature. H...

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Section: Discussionmentioning

confidence: 99%

A high-resolution thermoelectric module-based calorimeter for measuring the energetics of isolated ventricular trabeculae at body temperature

Johnston

Han

Ruddy

et al. 2015

American Journal of Physiology-Heart and Circulatory Physiology

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“…The preparation and apparatus have been described in detail previously Widén & Barclay, 2005) and only a brief description is provided here. Male Swiss mice, 6-12 weeks old, were rendered unconscious by inhalation of an 80% CO 2 -20% O 2 gas mixture (Kohler et al 1999) and killed by cervical dislocation.…”

Section: Papillary Muscle Preparationmentioning

confidence: 99%

“…Muscles were then allowed to equilibrate for 60 min. When first dissected, the resting metabolism of isolated papillary muscles is high and central anoxia can develop (Widén & Barclay, 2005). To minimize the possibility of this occurring, muscles were not stimulated during the equilibration.…”

Section: Experimental Protocolsmentioning

confidence: 99%

“…It has previously been shown that this passive force corresponds to a sarcomere length of ∼2.1 μm in these muscles (Widén & Barclay, 2005). Muscles were then allowed to equilibrate for 60 min.…”

Section: Experimental Protocolsmentioning

confidence: 99%

“…enthalpy output associated with cross-bridge activity) and a force-independent, or activation, component (i.e. enthalpy output associated primarily with ion pumping) by selectively inhibiting cross-bridge cycling with BDM and/or exposure to hyperosmotic solution (Alpert et al 1989;Widén & Barclay, 2005). The relationship between initial enthalpy output and the force-time integral (FTI) was determined by making incremental reductions in FTI by step-wise increases in BDM concentration from 2 to 10 mm.…”

Section: Partitioning Initial Metabolism Into Force-dependent and Formentioning

confidence: 99%

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ATP splitting by half the cross‐bridges can explain the twitch energetics of mouse papillary muscle

Widén

Barclay

2006

The Journal of Physiology

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The aim of this study was to quantify the fraction of cross-bridges that cycle during a cardiac twitch. Measurements of the energetics of contracting left ventricular mouse papillary muscle were made in vitro (27 • C) using the myothermic technique. Enthalpy output was partitioned into force-dependent and force-independent components using 2,3-butanedione monoxime (BDM) to selectively inhibit cross-bridge cycling. For isometric contractions and a contraction frequency of 2 Hz the net enthalpy output was 5.7 ± 0.8 mJ g -1 twitch -1 and initial enthalpy output was 2.3 ± 0.3 mJ g -1 twitch -1 (n = 11). Assuming that low concentrations of BDM did not affect Ca 2+ cycling, force-independent enthalpy output was 18.6 ± 1.9% (n = 7) of the initial enthalpy output. Enthalpy output decreased with increased contraction frequency but was independent of shortening velocity. On the basis of these values, it was calculated that the twitch energetics were consistent with ATP splitting by half the cross-bridges and the pumping of one Ca 2+ into the sarcoplasmic reticulum for every three cross-bridge cycles. The simplest interpretation is that half the cross-bridges completed one ATP-splitting cycle in each twitch. The lack of influence of shortening velocity on energy cost supports the idea that the amount of energy to be used is determined early in a twitch and is not greatly influenced by events that occur during the contraction.

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Contractility detection of isolated mouse papillary muscle using myotronic Myostation‐Intact device

Lian

Qin

Wu³

et al. 2022

Anim Models and Exp Med

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Background To understand the relationship between myocardial contractility and external stimuli, detecting ex vivo myocardial contractility is necessary. Methods We elaborated a method for contractility detection of isolated C57 mouse papillary muscle using Myostation‐Intact system under different frequencies, voltages, and calcium concentrations. Results The results indicated that the basal contractility of the papillary muscle was 0.27 ± 0.03 mN at 10 V, 500‐ms pulse duration, and 1 Hz. From 0.1 to 1.0 Hz, contractility decreased with an increase in frequency (0.45 ± 0.11–0.10 ± 0.02 mN). The voltage‐initiated muscle contractility varied from 3 to 6 V, and the contractility gradually increased as the voltage increased from 6 to 10 V (0.14 ± 0.02–0.28 ± 0.03 mN). Moreover, the muscle contractility increased when the calcium concentration was increased from 1.5 to 3 mM (0.45 ± 0.17–1.11 ± 0.05 mN); however, the contractility stopped increasing even when the concentration was increased to 7.5 mM (1.02 ± 0.23 mN). Conclusions Our method guaranteed the survivability of papillary muscle ex vivo and provided instructions for Myostation‐Intact users for isolated muscle contractility investigations.

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Resting metabolism of mouse papillary muscle

Cited by 13 publications

References 34 publications

A high-resolution thermoelectric module-based calorimeter for measuring the energetics of isolated ventricular trabeculae at body temperature

A high-resolution thermoelectric module-based calorimeter for measuring the energetics of isolated ventricular trabeculae at body temperature

ATP splitting by half the cross‐bridges can explain the twitch energetics of mouse papillary muscle

Contractility detection of isolated mouse papillary muscle using myotronic Myostation‐Intact device

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