Dynamics of contractile elements in isometric contractions of cardiac muscle

La, Yongfu; Ww, Parmley; Cw, Urschel; Eh, Sonnenblick

doi:10.1152/ajplegacy.1971.220.2.534

Cited by 18 publications

(7 citation statements)

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“…Theoretical Justification and Rationale Calculation of the velocity of shortening of the contractile element (V CE) during an isometric contraction is based on the concept that contractile element (CE) shortening is equal to series elastic extension (Yeatman et at., 1971;Parmley et at., 1972). The velocity of lengthening or shortening of a hypothetical spring (dl/dt) is equal to the rate of change of stress across the spring (da/dt) divided by the modulus of elasticity of the spring (do/dl).…”

Section: Calculation O F Isovolumic Contractile Element Velocitymentioning

confidence: 99%

“…It has been shown in papillary muscle that both the time course of V^e and the time of peak dP/dt are rather independent of preload ( Yeatman et al, 1971). V^e at the time of peak dP/dt should therefore be independent of preload and was evaluated in the intact heart as an index of contractility.…”

Section: Specific Indices O F Contractility Evaluatedmentioning

confidence: 99%

“…The rationale for the use of this methodology has been based on data from the isolated papillary muscle which demonstrates that indices of myocardial contractility may be obtained that accurately reflect changes in the inotropic state of the muscle but are rather insensitive to changes in initial fiber length (Sonnenblick, 1962;Brutsaert et al, 1970;Yeatman et al, 1971;Parmley et al, 1972). The application of these methods to the intact heart requires the use of several major assumptions, the validity of which have been ' Supported by US Army Contract No.…”

mentioning

confidence: 99%

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Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Cw¹,

Ps²,

Ah³

et al. 1980

Cardiology

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The accuracy, sensitivity and reproducibility of several isovolumic force-velocity indices of myocardial contractility were compared. Contractile element velocity was calculated using both two-element (total pressure) and three-element (developed pressure) models of cardiac muscle. While all indices demonstrated comparable sensitivity to inotropic state, only V_max using developed pressure was independent of preload and appeared to be a useful index of the myocardial contractile state.

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Section: Calculation O F Isovolumic Contractile Element Velocitymentioning

confidence: 99%

Section: Specific Indices O F Contractility Evaluatedmentioning

confidence: 99%

mentioning

confidence: 99%

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Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Cw¹,

Ps²,

Ah³

et al. 1980

Cardiology

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“…The ratio of rate of change of force divided by force at the same instant of time has been used in previous work (20,29) to provide an index which is defined as a velocity of internal shortening of the contractile element. This index is computed from the rate of change of stress divided by series element stiffness (AS/ALse).…”

Section: Length-independent Indices From Isometric Contractionmentioning

confidence: 99%

“…In heart muscle Vmax was shown to be length independent (27) but later studies, us ing improved experimental techniques, showed Vmax to change with length (24). Be cause of the length dependence of Vmax in isotonic shortening, heart muscle has been studied in isometric contraction to determine a v max of internal shortening (20) and other indices, such as the ratio of the rate of change of force divided by the active force (29). Their change with length, temperature, and calcium concentration was examined.…”

Section: Introductionmentioning

confidence: 99%

Contractility and the Length-Tension Relation of the Dog Anterior Tibial Artery

Price¹,

Davis²

1981

J Vasc Res

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Active force (S) and rate of change of force (S) throughout the time of isometric contraction in electrically stimulated, circumferentially cut segments of dog anterior tibial artery were analyzed for dynamic indices of the contractile state. Previous works have determined indices that change with temperature but not with length (L) or calcium (Ca) and were designated indices of crossbridge dynamics. They assumed that changes in L and Ca change only the number of crossbridges between contractile filaments and temperature affects only the dynamics of individual crossbridges. We have shown: (1) specific ratios of S/S to be independent of L; (2) S/S at the same instant of time (V*_CE) is related to an index from previous work which was defined as a velocity of internal shortening; (3) specific indices of S/S were decreased with lower temperature but increased with time in a Ca-free solution. Our results for a Ca-free solution do not agree with previous work but can be explained by changes of the smooth muscle cell membrane. This suggests that L-independent indices are useful for characterizing changes in the overall dynamic state of the tissue but are not necessarily representative of a change in crossbridge dynamics.

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Hill's equation applied to reconstituted contractile collagen

Balmer

Soto

1975

Biopolymers

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synopsisA new type of automatic force-displacement recording myograph has been developed to measure the contraction-relaxation characteristics of contractile systems. The device produces a polytonic (variable-force) load and therefore provides a more realistic measurement than either isometric or isotonic apparatus. Measurements on collagen that was first well ground and then extruded into a reconstituted thin tape show contraction and relaxation behavior that can be characterized by a slightly modified form of Hill's 1938 equation. The characteristic parameters of the Hill equation determined for the reconstituted collagen were remarkably similar to those of intact muscle tissue.

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Dynamics of contractile elements in isometric contractions of cardiac muscle

Cited by 18 publications

References 0 publications

Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Contractility and the Length-Tension Relation of the Dog Anterior Tibial Artery

Hill's equation applied to reconstituted contractile collagen

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