Autoregulation of contractility in the myocardial cell

Kaufmann, R.; Bayer, R; Harnasch, C.

doi:10.1007/bf00589087

Cited by 61 publications

(40 citation statements)

References 21 publications

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“…Deviations from the first two assumptions could also have caused a portion of the response to be misassigned to deactivation instead of the other components (or vice versa). However, the deactivation we found did behave similarly to that described for cardiac muscle (Brady, 1965;Kaufmann et al, 1972) in being more prominent the later in systole that displacement occurred.…”

Section: Critique Of Methods To Derive Mechanical Componentssupporting

confidence: 87%

“…These are analogous to two dominant mechanical characteristics of cardiac muscle: the forcelength and force-velocity relations (Brutsaert and Paulus, 1977;Weber and Janicki, 1977). The third mechanical phenomenon observed in the ventricle also has its counterpart in muscle mechanics: deactivation caused by a length change (Brady, 1965;Kaufmann et al, 1972). This similarity between the intact ventricle and isolated muscle encouraged us to seek explanations for the behavior of the ventricle in terms of phenomena observed with cardiac muscle.…”

Section: Comparison With Cardiac Musclementioning

confidence: 94%

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Systolic mechanical properties of the left ventricle. Effects of volume and contractile state.

Janicki

Weber

Noordergraaf

1983

Circulation Research

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SUMMARY. To characterize the mechanical properties of the contracting left ventricle, we studied the changes in left ventricular systolic pressure following step-like perturbations (±3 ml) in ventricular volume, using an isovolumically beating, isolated canine heart preparation. Three mechanical properties (elasticity, resistance, and a deactivation effect) were identified. The elastic property differs from the traditional parallel and series elastic elements; it is a time-varying elasticity that includes active and passive effects of volume changes. Furthermore, it could not be represented by a simple time-varying elasticity, but required a second factor to express the dependence of endsystolic elasticity on the timing of the volume step. This effect was represented by a "volume influence factor," which may arise from length-dependent activation. The resistive property appeared to be related to force-velocity behavior of the myocardium. Each mechanical property reacted characteristically to steady state changes in ventricular filling volume or contractile state produced by dobutamine (2-13 jug/min). Our findings indicate that elasticity was the property most sensitive to changes in contractile state; these changes increased peak isovolumetric pressure 54% on average, and raised elastic stiffness 40% above control (which was 5.1 mm Hg/ml). Changes in ventricular filling volume only prolonged, but did not alter, the level of elastic stiffness attained at peak pressure. These results support the view that elasticity-or the end-systolic pressure-volume relationshipserves in a given heart to quantify contractility. The "volume influence factor" was not affected by either filling volume or contractile state. Resistance increased in direct proportion with ventricular pressure, but this linear relation was not altered greatly by changes in contractile state or in ventricular filling volume. At 100 mm Hg, ventricular resistance averaged 0.11 mm Hg/ml per sec. Finally, deactivation was greater the later in systole a volume step was imposed, and this pattern was independent of changes in ventricular filling volume and in contractile state. (Ore Res 52: 319-327, 1983)

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Section: Critique Of Methods To Derive Mechanical Componentssupporting

confidence: 87%

Section: Comparison With Cardiac Musclementioning

confidence: 94%

Systolic mechanical properties of the left ventricle. Effects of volume and contractile state.

Janicki

Weber

Noordergraaf

1983

Circulation Research

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“…Mechanically induced deactivation of tension (Brady, 1965;Kaufmann et al, 1972;Julian and Moss, 1976) has properties similar to those outlined in Section II above: it occurs during muscle activity, is rapid, and directional. Further, Gordon and Ridgeway (1976) found a Ca ++ mediated length-dependent change in membrane potential in skeletal muscle.…”

Section: (Ii) Active Indirect Mechanismmentioning

confidence: 98%

“…2B). Mechanically induced "uncoupling of the active state" is also a time-dependent process (Brady, 1965;Kaufmann et al, 1972). In this process, a release of the muscle to a short length during contraction is incapable of producing an active tension appropriate for the new length: this phenomenon is called "tension deactivation" (Julian and Moss, 1976).…”

Section: (Ii) Mechanical Changes In Active Musclementioning

confidence: 99%

Contraction-excitation feedback in myocardium. Physiological basis and clinical relevance.

Lab¹

1982

Circulation Research

293

130

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“…However, to get the percent shortening obtained in the present study, the isolated papillary muscles must shorten almost under conditions of zero afterload (as in a quickrelease preparation). Yet experimental data on isolated cardiac muscle (2) as well as skeletal muscle (36) suggest that maximum rapid shortening is incompatible with large tension development, possibly because the so-called active state may be reduced by rapid length changes (quick stretch or quick release [37]). Recently, however, data obtained by Edman and Nilsson (6) using damped releases, which may more nearly duplicate in vivo conditions, suggest that both large tension development and considerable shortening can occur simultaneously.…”

Section: Discussionmentioning

confidence: 99%

Papillary muscle shortening in the intact dog; a cinderadiographic study of tranquilized dogs in the upright position.

Grimm¹,

Lendrum²,

Lin³

1975

Circulation Research

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Shortening of the anterior papillary muscle of the left ventricle was demonstrated in six intact, tranquilized dogs. Two small metal markers that had been surgically implanted 3-50 months earlier were cineradiographically photographed during approximately ten sequential cardiac cycles in each of two orthogonal positions. Distances between markers were plotted for successive frames. The resulting curves were used to obtain maximum velocities of papillary muscle shortening and lengthening: 1.08 ± 0.29 muscle lengths/sec and 1.39 ± 0.48 muscle lengths/sec, respectively. From the two orthogonal planes, the average maximum spatial distance and the average minimum spatial distance between the markers were calculated. The mean percent shortening of 22.8 ± 6.5% was surprisingly large: it approximated the distance from the foot to the peak of the ascending limb of the myocardial lengthtension curve derived from isolated muscle studies. Mechanical studies on isolated papillary muscle have consistently shown reduced shortening with increasing loads. Since the in vivo dog papillary muscle has been reported to be under considerable tension during systole, there appears to be some contradiction between the degree of shortening found in the present study and the shortening observed in isolated papillary muscle studies. KEY WORDSmvocardial shortening length-tension curves cardiac metal markers myocardial velocities electrocardiogram• Papillary muscle has been investigated for two relatively independent reasons: (1) it is an experimentally convenient sample of ventricular myocardium, and (2) it is a clinically important portion of the functioning heart. Papillary muscle is easy to isolate and to remove from the ventricle. Its small diameter in some species and its participation during cardiac growth also contribute to its utility as an experimental material. Most papillary muscle studies have employed the isolated muscle (1-10), although more recently mechanical properties have been studied in the in situ muscle (11)(12)(13)(14). The essentially linear fiber arrangement within the muscle greatly simplifies the interpretation This work was supported in part by U. S. Public Health Service Grant 1 R01 HL-14651-01 from the National Heart and Lung Institute.A preliminary report on some of these results has been previously presented in abstract form (Fed Proc 27:2699, 1968.Received July 2, 1973. Accepted for publication September 6, 1974. Circulation Research, Vol. 36, January 1975 of data from both mechanical and microscopic studies (15).Papillary muscle function in the intact heart has, most often, been deduced indirectly from isolated muscle studies, clinical observations, autopsy reports, and theoretical considerations. Burch et al. (16) and Burch and Depasquale (17) have postulated that during ventricular systole the papillary muscle, by creating tension, acts as a stay to restrict mitral valve motion. When normal tension development does not occur, excessive mitral valve motion results in mitral regurgitation (the p...

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Autoregulation of contractility in the myocardial cell

Cited by 61 publications

References 21 publications

Systolic mechanical properties of the left ventricle. Effects of volume and contractile state.

Systolic mechanical properties of the left ventricle. Effects of volume and contractile state.

Contraction-excitation feedback in myocardium. Physiological basis and clinical relevance.

Papillary muscle shortening in the intact dog; a cinderadiographic study of tranquilized dogs in the upright position.

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