Strain softening is not present during axial extensions of rat intact right ventricular trabeculae in the presence or absence of 2,3-butanedione monoxime

Kirton, Robert; Taberner, Andrew J.; Young, Alistair A.; Nielsen, Poul M. F.; Loiselle, Denis S.

doi:10.1152/ajpheart.00580.2003

Cited by 15 publications

(29 citation statements)

References 44 publications

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“…However, no such effect has been reported in high (12) or low (14,27) Ca 2ϩ in skinned cardiac preparations. Furthermore, even if a BDM-induced increase in the passive tension-length relation had been observed in intact cardiac trabeculae [which is unlikely, because Kirton et al (21) found no increase], this would more likely have caused an increase of stiffness at all frequencies [as observed during the formation of rigor cross bridges (20)] than the frequency dependence shown in Fig. 3.…”

Section: Discussionmentioning

confidence: 95%

“…However, when right ventricular trabeculae from rat are subjected to such experimental conditions, spontaneous, asynchronized "waves" of contractile movement, commonly called "writhing," are reported (7,13,21,41). In trabeculae that were deemed to be viable, raising the temperature to 25°C significantly reduced the degree of writhing (7,21 ] i (and, hence, the degree of cross-bridge cycling and resting tension) is higher at lower temperatures in nominally quiescent cardiac muscle tissue. Such phenomena have been reported, without elaboration, during dynamic stiffness measurements of intact, quiescent kitten papillary muscles, in which increased temperature resulted in decreased dynamic stiffness (34).…”

Section: Discussionmentioning

confidence: 99%

“…It is thus an ideal species in which to examine the effects, on the mechanical properties of passive cardiac muscle, of temperature and Ca 2ϩ , in combination with BDM, an inhibitor of cross-bridge activity. It must be emphasized that such investigation must be performed in cardiac tissue that is known to be healthy (i.e., to respond to electrical stimulation), inasmuch as recent studies have demonstrated that the stress vs. muscle length relationships (21) and dynamic stiffness (20) of passive cardiac tissue are significantly altered on loss of tissue viability.…”

Section: Discussionmentioning

confidence: 99%

“…During Langendorff perfusion of the heart with oxygenated dissection solution, its right ventricle was opened, and a trabecula that was relatively long (2.12 (SD 0.66) mm, n ϭ 15) and sufficiently thin (174 (SD 54) ϫ 255 (SD 104) m) to ensure adequate oxygenation (6,36) was excised. The trabecula was mounted between an oscillatory motor and a force transducer, as described previously (20,21). BDM was then washed out, and the trabecula was stimulated electrically until twitch force remained stable for Ն30 min.…”

Section: Methodsmentioning

confidence: 99%

“…More recently, the use of BDM has further ensured passivity (10,11); yet its effects on the mechanical properties of quiescent cardiac tissue at room temperature (20 -22°C) and low [Ca 2ϩ ] o have not been explored. At 26°C and 0.5 mM [Ca 2ϩ ] o , BDM was found to have no effect on the stress vs. muscle length extension relationships of healthy, intact rat trabeculae (21). Similarly, the passive tension and small-amplitude sinusoidal stiffness of skinned cardiac myocytes (14) and skinned cardiac myofibrils (27) were unaffected by BDM.…”

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confidence: 90%

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Effects of BDM, [Ca²⁺]_o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Kirton¹,

Taberner²,

Nielsen³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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([Ca 2ϩ ]o). More recently, the negative inotropic agent 2,3-butanedione monoxime (BDM) has been used. However, there remains a lack of data regarding the influence of temperature, Ca 2ϩ , and BDM on the passive mechanical properties of cardiac tissue. We have used the dynamic stiffness technique, a sensitive measurement of cross-bridge activity, in which minute (ϳ0.2% of muscle length) sinusoidal perturbations are applied at various frequencies (0.2-100 Hz) to quiescent, viable right ventricular rat trabeculae at two temperatures (20°C and 26°C) and at two [Ca 2ϩ ]o (0.5 and 1.25 mM) in the presence and absence of BDM (20 mM). The stiffness spectra (amplitude and phase) were sensitive to temperature and [Ca 2ϩ ]o in the absence of BDM but insensitive in the presence of BDM. From the index of cross-bridge cycling (the ratio of high-to low-frequency stiffness amplitude), we infer that BDM inhibits a small degree of spontaneous sarcomere activity, thereby allowing the true passive properties of trabeculae to be determined. In the absence of BDM, the extent of spontaneous sarcomere activity decreases with increasing temperature. We caution that the measured mechanical properties of passive cardiac tissue are critically dependent on the experimental conditions under which they are measured. Experiments must be performed at sufficiently high temperatures (Ͼ25°C) to ensure a low resting concentration of intracellular Ca 2ϩ or in the presence of an inhibitor of cross-bridge cycling. cardiac muscle; sinusoidal length perturbation; passive mechanics; 2,3-butanedione monoxime; extracellular calcium concentration THE MECHANICAL PROPERTIES of passive cardiac tissue are important, inasmuch as they help determine the stroke volume of the heart (3) and, hence, play a major role in diastolic dysfunction observed clinically. Mechanical tests are commonly performed on isolated hearts or samples of cardiac tissue and are conducted at various temperatures and extracellular Ca 2ϩ concentrations ([Ca 2ϩ ] o ). Recent studies (10, 11) have exploited the negative inotropic action (37) and cardioprotective properties (30) of the chemical agent 2,3-butanedione monoxime (BDM), whereas earlier studies utilized other forms of arrest.It ] o (9, 32), although Pinto and Patitucci (32) stated that temperature had little effect on the rate of creep of passive cardiac tissue. BDM has been reported to offer protection from cutting injury (30) and the Ca 2ϩ paradox (5), as well as from hypoxia and reperfusion injury (31). It also inhibits, but does not prevent, contracture (17).To ensure that cardiac muscle preparations are truly "passive," experiments have traditionally been conducted at low [Ca 2ϩ ] o and, for convenience, at room temperature. More recently, the use of BDM has further ensured passivity (10, 11); yet its effects on the mechanical properties of quiescent cardiac tissue at room temperature (20 -22°C) and low [Ca 2ϩ ] o have not been explored. At 26°C and 0.5 mM [Ca 2ϩ ] o , BDM was found to have no effect on the...

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 90%

See 3 more Smart Citations

Effects of BDM, [Ca²⁺]_o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Kirton¹,

Taberner²,

Nielsen³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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Force Measurement

Anderson

Lim

2006

Wiley Encyclopedia of Biomedical Engineering

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A variety of transduction technologies are available for the measurement of force. Some of the more common ones, including strain gauge and piezoelectric types, are described in this article. There are several important considerations when dealing with force measurement, which include measurement range, linearity, accuracy, sensitivity, frequency response, and aliasing. The accuracy of the force measurement can be limited by incorrect interpretation of the output from a transducer. Errors can occur due to poor sensitivity and nonlinear behavior. The measurement of dynamic force also requires consideration of the frequency response characteristics of a transducer. To avoid large errors, it is important to choose a force transducer with a natural frequency that is significantly greater than the maximum frequency of interest in the force measurement. Choice of transduction technology will deal with most of these issues to a greater or lesser degree. Examples of specific applications of force measurement in biomedical engineering will be presented in this article.

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Mechanics of Vascular Smooth Muscle

Ratz

2015

Comprehensive Physiology

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Vascular smooth muscle (VSM; see Table 1 for a list of abbreviations) is a heterogeneous biomaterial comprised of cells and extracellular matrix. By surrounding tubes of endothelial cells, VSM forms a regulated network, the vasculature, through which oxygenated blood supplies specialized organs, permitting the development of large multicellular organisms. VSM cells, the engine of the vasculature, house a set of regulated nanomotors that permit rapid stress-development, sustained stress-maintenance and vessel constriction. Viscoelastic materials within, surrounding and attached to VSM cells, comprised largely of polymeric proteins with complex mechanical characteristics, assist the engine with countering loads imposed by the heart pump, and with control of relengthening after constriction. The complexity of this smart material can be reduced by classical mechanical studies combined with circuit modeling using spring and dashpot elements. Evaluation of the mechanical characteristics of VSM requires a more complete understanding of the mechanics and regulation of its biochemical parts, and ultimately, an understanding of how these parts work together to form the machinery of the vascular tree. Current molecular studies provide detailed mechanical data about single polymeric molecules, revealing viscoelasticity and plasticity at the protein domain level, the unique biological slip-catch bond, and a regulated two-step actomyosin power stroke. At the tissue level, new insight into acutely dynamic stress-strain behavior reveals smooth muscle to exhibit adaptive plasticity. At its core, physiology aims to describe the complex interactions of molecular systems, clarifying structure-function relationships and regulation of biological machines. The intent of this review is to provide a comprehensive presentation of one biomachine, VSM.

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Strain softening is not present during axial extensions of rat intact right ventricular trabeculae in the presence or absence of 2,3-butanedione monoxime

Cited by 15 publications

References 44 publications

Effects of BDM, [Ca²⁺]_o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Effects of BDM, [Ca²⁺]_o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Force Measurement

Mechanics of Vascular Smooth Muscle

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Strain softening is not present during axial extensions of rat intact right ventricular trabeculae in the presence or absence of 2,3-butanedione monoxime

Cited by 15 publications

References 44 publications

Effects of BDM, [Ca2+]o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Effects of BDM, [Ca2+]o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Force Measurement

Mechanics of Vascular Smooth Muscle

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Effects of BDM, [Ca²⁺]_o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat

Effects of BDM, [Ca²⁺]_o, and temperature on the dynamic stiffness of quiescent cardiac trabeculae from rat